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DEPARTMENT OF 

AERONAUTICS and ASTRONAUTICS 

MASSACHUSETTS INSTITUTE OF TECHNOLOGY 

CAMBRIDGE, MASSACHUSETTS 02139-4307 



6&-W 



MIT AERONAUTICAL SYSTEMS LABORATORY 



VARIATIONS IN PARTY LINE INFORMATION REQUIREMENTS 

FOR FLIGHT CREW SITUATION AWARENESS IN THE 

DATALINK ENVIRONMENT 



Amy R. Pritchett 
R. John Hansman 



Aeronautical Systems Laboratory 

Department of Aeronautics and Astronautics 

Massachusetts Institute of Technology 

Cambridge, Massachusetts USA 



18 May 1994 
ASL-94-5 



Variations in Party Line Information Requirements For 
Flight Crew Situation Awareness in the Datalink 

Environment 

Abstract 



Current Air Traffic Control communications use shared VHF voice frequencies 
from which pilots can obtain 'Party Line' Information (PLI) by overhearing 
communications addressed to other aircraft. A prior study has shown pilots perceive this 
PLI to be important. There is concern that some critical PLI may be lost in the proposed 
datalink environment where communications will be discretely addressed. Different 
types of flight operations will be equipped with datalink equipment at different times, 
generating a 'mixed environment' where some pilots may rely on PLI while others will 
receive their information by datalink. To research the importance, availability and 
accuracy of PLI and to query pilots on the information they feel is necessary, a survey 
was distributed to pilots. The pilots were selected from four flight operation groups to 
study the variations in PLI requirements in the mixed datalink environment. Pilots 
perceived PLI to be important overall. Specific information elements pertaining to traffic 
and weather information were identified as Critical. Most PLI elements followed a 
pattern of higher perceived importance during terminal area operations, final approach 
and landing. Pilots from the different flight operation groups identified some elements as 
particularly important. Pilots perceived PLI to be only moderately available and accurate 
overall. Several PLI elements received very low availability and accuracy ratings but are 
perceived as important In a free response question designed to find the information 
requirements for global situation awareness, pilots frequently indicated a need for traffic 
and weather information. These elements were also frequently cited by them as 
information that could be presented by a datalink system. The results of this survey 
identify specific concerns to be addressed when implementing datalink communications. 



This document is based on the thesis of Amy R. Pritchett submitted in partial 
fulfillment of the degree of Master of Science in Aeronautics and Astronautics at the 
Massachusetts Institute of Technology. 



Acknowledgements 



This work was supported by the National Aeronautics and Space Administration/ 
Ames Research Center and the Federal Aviation Administration under grant NAG 2-716. 

The authors would like to acknowledge the following persons for their 
contributions to this study: 

- Bob Hall of the Air Line Pilots Association and the many airline safety 
representatives who helped distribute this survey to the air carrier pilots. 

- The military squadrons who helped in distributing this survey to the appropriate 
military pilots. 

- The many pilots who took the time to complete the survey. 



Contents 

Abstract 2 

Acknowledgements 3 

Contents 4 

Chapter 1: Introduction 6 

Chapter 2: Survey Design, Distribution and Analysis 10 

2.1 Survey Design \\ 

2.1.1 Importance, Availability and Accuracy Ratings 11 

2.1.2 Datalink Implementation Questions 15 

2.2 Distribution and Response Rate 17 

2.3 Data Analysis 18 

2.3.1 Analysis of PLI Importance, Availability and Accuracy Ratings .18 

2.3.2 Subjective Responses 21 

Chapter 3: Importance, Availability and Accuracy Ratings of PLI Elements 22 

3.1 Importance Ratings 23 

3.1.1 Overall Importance Ratings 23 

3. 1.2 PLI Elements Rated Critical in a Majority of Responses 23 

3.1.3 Other Elements Rated as Important by a Majority of Pilots 25 

3.1.4 PLI Elements Receiving Lower Importance Ratings 27 

3. 1.5 Importance Ratings of PLI Elements Not Specific to Phase 

of Flight 28 

3.2 Availability and Accuracy Ratings 29 

3.2.1 Correlation Between Availability and Accuracy Ratings 30 

3.2.2 Correlation Between Importance Ratings and Availability or 
Accuracy Ratings 31 

Chapter 4: Variation in Party Line Information Importance Between Phases of Flight.33 

4.1 Flight Operations Throughout All Phases of Flight 34 

4.1.1 Descriptions of Each Phase of Flight 35 

4.1.2 Changes in Right Characteristics Between Phase of Flight 37 

4.2 Overall Variance of PLI Importance with Phase of Flight 39 

4.3 Variance of Weather PLI Importance with Phase of Flight 40 

4.3.1 Variance of Weather Overall 40 

4.3.2 Weather PLI Elements Consistently Important for All Phases 

of Flight 42 

4.3.3 Weather PLI Elements Rated Lower in Cruise, Higher on Final 
Approach 44 

4.3.4 Elements Rated only for Final Approach 46 

4.3.5 PLI Weather Elements with the Highest Importance During 
Cruise 46 



4.4 Variance of Traffic PLI Importance with Phase of Flight 48 

4.4.1 Traffic Avoidance PLI Elements 48 

4.4.2 Traffic Planning PLI Elements 50 

4.5 Other PLI Elements 52 

Chapter 5: Variation in PLI Importance Between Flight Operations Groups 53 

5.1 Pilot Characteristics 54 

5.2 Variation in PLI Importance Ratings in All Phases of Flight 56 

5.3 PLI Elements Perceived More Important by Major Airline Pilots 59 

5.4 PLI Elements Perceived More Important by Commuter Airline Pilots 60 

5.5 PLI Elements Perceived More Important by General Aviation Pilots 61 

5.6 PLI Elements Perceived More Important by Military Pilots 66 

Chapter 6: Pilot Information Requirements Subjective Responses 67 

6.1 Information Required for Global Situation Awareness 68 

6.2 Information Pilots Would Like Provided by Datalink 70 

6.3 Pilot Preferred Mix of Voice and Datalink Communications 72 

Chapter 7: Survey Conclusions 73 

References 76 

Appendix A: Sample Copy of Party Line Information and Datalink Survey 

Appendix B: Background Information Summary 

Appendix C: Importance, Availability and Accuracy Ratings of Party Line Information, 

Listed by PLI Element 
Appendix D: Importance Ratings of Party Line Information, Listed by Phase of Flight 
Appendix E: Importance Ratings of Party Line Information from Pilots of Different 

Flight Operations 
Appendix F: Subjective Responses 



Chapter One 
Introduction 

Current Air Traffic Control (ATC) communications use shared VHF voice 
frequencies . Because each frequency is monitored by the ATC facility and several 
aircraft, pilots can receive not only their own 'direct' transmissions from ATC, but can 
also overhear communications addressed to other aircraft. This 'Party Line' effect can 
provide many types of supplementary information, as shown in Figure 1.1. Therefore, 
many pilots consider this 'Party Line' Information (PLI) to be a valuable resource (Ref. 
Midkiff, 1992). 



•TitMeAwManca •Swiumdng 




Figure 1.1 Party Line Information 



There are, however, significant limitations of the voice system as indicated by the 
high number of Aviation Safety and Reporting System (ASRS) submissions identifying 
breakdowns and saturation in VHF voice channels. For example, of the more than 14,000 
ASRS reports received in 1985 and 1986, one fourth involved problems in air/ground 
information transfer (Ref. Lee & Lozito, 1989). 



The Federal Aviation Administration's (FA A) National Airspace modernization 
plan calls for the implementation of digital datalink communications for air/ground 
information exchange between aircraft and ATC facilities. The Airline Transport 
Association (ATA) has also recommended as early as possible use of datalink 
communications between ATC and aircraft and data transmission to an aircraft's flight 
management system without need for voice communications. (Ref. Aviation Week & 
Space Technology, 1994) 

Datalink communications offer increased system safety and efficiency by 
reducing transmissions and interpretation errors and by allowing a greater exchange of 
information. This system of communications may also relieve the overloading of ATC 
radio frequencies, which hamper efficient message exchanges during peak traffic periods 
in many busy terminal areas. (Ref. Knox & Scanlon, 1990) 

To the pilot, the most obvious datalink system to date has been the ARINC 
Communication Addressing and Reporting System (ACARS) developed and in use by 
several major airlines. The ACARS unit in the cockpit is a terminal with which 
information can be exchanged between the aircraft and airline operations. Pilots can 
receive digital Automatic Terminal Information System (ATIS) messages, PreDeparture 
Clearances (PDC), and gate and arrival information. Pilots can downlink messages such 
as arrival estimates and requests for weather reports. Automatic downlinks of aircraft 
departure time and engine performance data are also in common use. (Ref. Midkiff, 
1992, Ryan, 1992, Armstrong, 1992) 

With the advent of satellite voice and digital communications, several other 
additions to these datalink communications are being proposed and tested. For example, 
Automatic position reports during oceanic flights are being tested with some airlines on 
both Pacific and North Atlantic routes, using the Automatic Dependent Surveillance 
system (ADS). (Ref. Lorge, 1993, Armstrong, 1992, Ryan, 1992) 

Because future datalink communications can provide ADS position reports and 
can transmit a substantial amount of detailed flight path information directly to the 
aircraft's Flight Management Computers, several other benefits are being analyzed. With 
better knowledge of aircraft positions outside normal radar coverage, such as on oceanic 
flights, the possibility of reducing aircraft separations is already being analyzed to allow 
for more efficient use of the airspace. More efficient use of airspace can also be 
envisioned in next generation ATC systems which can negotiate direct flight routings 



with aircraft flight management computers, allowing for the most direct and efficient 
flight routes without being constrained to established airways. (Ref. Lorge, 1993, den 
Braven, 1992, Ryan, 1992) 

The pilots' responses to the datalink tests run so far have been positive. However, 
before datalink ATC communications become more than a supplementary or 
experimental system, several human factors issues must be examined. For example, the 
discrete nature of datalink addressing (where each transmission is directed only to 
specific aircraft) may cause less information to be presented by PLI. However, before 
any compensation methods for PLI loss can be determined, a solid understanding of 
current PLI use and importance must be obtained. (Ref. Knox & Scanlon, 1990, 
Armstrong, 1992, Midkiff, 1992) 

The importance of PLI overall and of specific PLI elements was examined in a 
previous study. This study made several valuable observations based on an airline pilot 
opinion study and a full mission flight simulation study. PLI was generally identified as 
important, with some specific traffic or weather PLI elements receiving critical ratings. 
The PLI elements received the highest importance ratings during the aircraft's arrival; 
because this phase of flight is the most time critical, the final tower controller frequency 
was concluded to be a less desirable candidate for initial datalink implementation than 
other "enroute" operations. Some specific PLI elements were perceived as important but 
not very reliable, indicating information for which the 'Party Line' is not the best 
modality of communication. Finally, pilots indicated they were more receptive to the 
implementation of datalink if compensation is included for any PLI loss. However, this 
study surveyed only one distinct group of pilots ~ current American Airlines aircrew 
based at Chicago O'Hare - and therefore may not represent the diverse concerns of the 
entire aviation community. (Ref. Midkiff, 1992) 

This report documents a continuing study of current PLI use and importance. A 
pilot opinion survey was developed, based upon the survey from Midkiff s study. The 
distribution of the survey was increased to include additional operational groups with a 
wide geographic spread. Several PLI elements were expanded into more specific 
components to better examine the 'Traffic' and 'Weather' elements previously identified 
as important in the Midkiff study. 



This study continues with several objectives with Midkiff' s survey in determining 
the use and importance of Party Line Information: 

1) Determine the Importance, Availability and Accuracy of both 'Party 

Line' Information overall, and of specific PLI elements, 

2) Determine how PLI usage varies with different flight regimes, & 

3) Solicit pilot opinions on datalink implementation. 

The results of Midkiffs study identified several issues requiring further study. 
Therefore, this survey also had several additional objectives to provide greater detail 
about the various factors affecting PLI importance and pilot situational awareness: 

4) Expand the distribution of the survey to study any variations of PLI 

usage between pilots from different types of flight operations, 

5) Include more specific PLI elements to allow for a more exact 

determination of the important PLI elements pertaining to weather 
and traffic information, & 

6) Solicit pilot opinions on the information required for situation 

awareness. 

The survey design, distribution and analysis are detailed in Chapter 2. Chapters 3, 
4 and 5 discuss the numerical Importance, Availability and Accuracy ratings of specific 
PLI elements, and Chapter 6 discusses the pilots' subjective responses. Finally, Chapter 
7 summarizes the important results and conclusions of the study. 



Chapter Two 
Survey Design, Distribution and Analysis 



The pilot opinion survey was designed to solicit both ratings of PLI Importance, 
Availability and Accuracy, and pilot opinions on datalink implementation and situation 
awareness. This survey was based upon the one distributed in the Midkiff study (Ref . 
Midkiff 1992), with both the content and distribution expanded. 

The Midkiff study identified PLI elements pertaining to Traffic and Weather 
information as being particularly important. Therefore, the content of this survey 
included several expanded sections requesting more detailed responses about these PLI 
elements. A free-response question was added asking pilots "What does the 'Big Picture' 
mean to you?" in an effort to identify information pilots feel is necessary for Global 
Situation Awareness. 

The previous survey specifically focused on airline PLI requirements and was 
only distributed to American Airline pilots based at the Chicago O'Hare airport. The 
distribution of this survey was increased to include pilots of additional types of flight 
operations, including General Aviation, Regional/Commuter Airlines, Major Air Line 
and Military operations. 

This chapter will detail the survey design, distribution and analysis. A copy of the 
survey is included in Appendix A. A summary of the characteristics of the respondents is 
included in Appendix B. 



10 



2.1 Survey Design 

The survey was organized into three sections. The first and largest section 
requested numerical ratings of the Importance, Availability and Accuracy of specific PLI 
elements. The second section investigated issues relating to datalink implementation and 
to the information requirements for global situation awareness. The third section 
gathered information about the respondents' characteristics and flight experience. 

Several other documents accompanied the survey. A cover letter detailed the 
purpose and importance of the survey as a potential input by pilots into the development 
of datalink systems. A separate study included at the end surveyed the use and 
importance of current cockpit displays for providing weather information. 

2.1.1 Importance, Availability and Accuracy Ratings 

To examine how pilots use PLI, numerical ratings of the Importance, Availability 
and Accuracy of specific information PLI elements were solicited. These PLI elements 
were selected for their likely importance to pilots, based upon the original list of elements 
determined by Midkiff through exploratory studies with active airline air crew. Because 
the PLI elements relating to Traffic and Weather information were identified as 
particularly important, this survey included additional PLI elements to provide more 
detailed ratings about these types of information. For example, in addition to a rating for 
the information element Weather Overall, pilots were also asked to rate the individual 
factors contributing to weather conditions. Pilots were also requested to provide 
additional PLI elements in an Other category for each phase of flight 

PLI usage for many elements has been found to vary throughout the course of a 
flight (Ref. Midkiff, 1992). Therefore, most of the PLI elements were surveyed in each 
of the appropriate Phases of Flight, defined in Table 2.1. The elements listed under each 
Phase of Flight are given in Table 2.2. 

Ground Operations (G.Ops) Pre-Start, Taxi 

Departure (Dep) Takeoff to Top of Climb 

Cruise Top of Climb to Top of Descent 

Descent (Des) Top of Descent to Approach Control Contact 

Terminal Area (TA) Approach Control Contact to Final Approach Fix 

Final Approach (FA) Final Approach Fix to Runway Threshold 

Table 2.1 - Phases of Flight Surveyed 

11 



Ground Operations 

Next Communications Frequency 
Weather Situation 
-Overall 

- TRW Buildups & Deviations 

- Visibility & Ceiling 

- Icing Conditions 

- Ride Reports / Turbulence 

- Winds Aloft 

- Surface Winds 
Routing to Runway 

Relative Sequencing of Other A/C 
"Hold Short" Instructions of Other A/C 
A/C Crossing Active Runway While You 

Are Lined Up for Take Off 
Error or Mistake of the Controller 
Other 



Departure 

Next Communications Frequency 
Weather Situation 
-Overall 

- TRW Buildups & Deviations 

- Visibility & Ceiling 

- Icing Conditions 

- Ride Reports / Turbulence 

- Winds Aloft 

- Surface Winds 
Traffic Avoidance 

- Controlled Airports 

- Uncontrolled Airports 
Relative Sequencing of Other A/C 

Error or Mistake of the Controller 
Other 



Cruise 

Next Communications Frequency 
Weather Situation 
-Overall 

- TRW Buildups & Deviations 

- Visibility & Ceiling 

- Icing Conditions 

- Ride Reports / Turbulence 

- Winds Aloft 

- Surface Winds 
Traffic Avoidance 

Relative Sequencing of Other A/C 
Error or Mistake of the Controller 
Other 



Descent 

Next Communications Frequency 
Weather Situation 
-Overall 

- TRW Buildups & Deviations 

- Visibility & Ceiling 

- Icing Conditions 

- Ride Reports / Turbulence 
-Winds Aloft 

- Surface Winds 
Traffic Avoidance 

- Controlled Airports 

- Uncontrolled Airports 
Relative Sequencing of Other A/C 
Holding Situations / EFC Validity 
Error or Mistake of the Controller 
Other 



Terminal Area 

Next Communications Frequency 
Weather Situation 
-Overall 

- TRW Buildups & Deviations 

- Visibility & Ceiling 

- Icing Conditions 

- Ride Reports / Turbulence 

- Winds Aloft 

- Surface Winds 
Traffic Avoidance 

Relative Sequencing of Other A/C 
Holding Situations /EFC Validity 
Terminal Routing / Runway Assignments 
Approach Clearance 
Error or Mistake of the Controller 
Other 



Final Approach 

Next Communications Frequency 
Weather Situation 
-Overall 

- TRW Buildups & Deviations 

- Visibility & Ceiling 

- Icing Conditions 

- Ride Reports / Turbulence 

- Winds Aloft 

- Windshear 

- Surface Winds 
Traffic Avoidance 

- Controlled Airports 

- Uncontrolled Airports 
Missed Approach - Weather Induced 
Missed Approach - Other 
Aircraft On Your Landing Runway 
Braking Action 

Taxiway Turnoff/Planned Runway Exit 
Relative Sequencing of Other A/C 
Error or Mistake of the Controller 
Other 



Table 2.2 -- PLI Elements Listed With Each Phase of Flight 



12 



A separate section requested the ratings for the General PLI elements that do not 
vary significantly with phase of flight, such as Navaid Problems, and for the Prosodic 
PLI elements made available by voice inflection or phraseology, such as Controller's 
Experience Level. These elements are listed in Table 2.3. 

Sector Congestion (As Indicated by Frequency Congestion) 

Controller's Experience Level (Inferred From Tone of Voice and Speech Patterns) 

Pilot's (Of Other Aircraft) Experience Level (Inferred From Tone of Voice and 

Speech Patterns) 
Controller's "Level of Urgency" (Inferred From Tone of Voice and Speech 

Patterns) 

Pilot's (Of Other Aircraft) "Level Of Urgency" (Inferred From Tone Of Voice And 
Speech Patterns) 

Background ATC Transmissions Used as Reassurance of Being "In Contact" With 
the Controller. ("Anybody Out There?") 

Call Sign Confusion (Other Aircraft Accepting Your Clearance or Vice Versa) 

ATC Facility Problems / Lost Communications 

Navaid Problems 

Other 

Table 2.3 - General and Prosodic PLI Elements 



This expanded list of PLI elements contained some elements that may not be 
relevant to all the pilots given the survey with their differences in flight operations. For 
example, the PLI element Traffic - Uncontrolled Airports may not be relevant to 
Major Airline pilots accustomed to flying into only large, controlled airports. Therefore, 
pilots were asked to only rate those elements applicable to their accustomed flight 
operations. 

A small sample of the rating section, shown in Figure 2.1, illustrates the format 
that allowed pilots to simultaneously rate the Importance, Availability and Accuracy of 
each PLI element. The Importance ratings were on a scale from 1 (Trivial) to 5 
(Critical)with Importance defined at the beginning of the survey as 'How important is 
each item?' The Availability ratings were on a scale from 1 (Non-Existent) to 5 
(Common-Place), with availability defined as 'How available is the information when 
you need it?'. The Accuracy ratings were on a scale from 1 (Unreliable) to 5 (Reliable), 
where accuracy was defined as 'Is Party Line Information a good indication of the actual 
situation?' 

13 



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2.1.2 Datalink Implementation Questions 

Pilot opinions were solicited on several issues associated with the information 
required for situation awareness, datalink implementation, and current cockpit displays. 

First, pilots were asked for free responses to the three subjective questions. The 
first question, which asked about the concept of the "Big Picture" in an attempt to 
identify the specific information elements which pilots require for global situation 
awareness, was: 

There is a concern that, without "Party Line" Information, pilots may lose a 
sense of the "Big Picture." What does the "Big Picture" mean to you? 

The next two questions asked for pilot input about the specific information 
content suitable for datalink systems, possible methods of displaying this information, 
and possible mechanisms to compensate for any PLI loss caused by datalink 
communications. They were: 

Is there any particular information or images which you fee I should be datalinked 
to aircraft? Do you have any suggestions for displaying this information in the cockpit? 

Can you suggest any methods of compensating for the loss of "Party Line" 
Information when using a digital datalink and some form of electronic display? 

The next questions asked pilots to identify the mix of voice and datalink 
communications they would prefer both for systems that included some form of 
compensation for any PLI loss and for systems that did not. These ratings were given on 
the five point scales, as shown in Figure 2.2 



15 



Considering the advantages of datalink (such as frequency congestion relief, 
unambiguous clearances, etc.) and of party line information (a 'sense of the big 
picture', ability to hear communications of all other aircraft in the sector), what mix of 
datalink and voice communications would you like to see? 



1 


2 3 


4 


5 


DATALINK 


EQUAL 




VHF VOICE 


ONLY 


DISTRIBUTION 




COMMUNICATION 




VOICE /DATALINK 




ONLY 



If some mechanism could be developed to datalink critical party line information to 
the aircraft (e.g. a status display with current wx, sequencing, and/or holding 
information), what mix of datalink and voice communications would you like? 



1 


2 3 


4 


5 


DATALINK 


EQUAL 




VHF VOICE 


ONLY 


DISTRIBUTION 




COMMUNICATION 




VOICE /DATALINK 




ONLY 



Figure 2.2 -- Preferred Mix of Voice and Datalink Communication Questions 



16 



2.2 Distribution and Response Rate 

In order to expand upon the survey responses from the Midkiff study, this survey 
was distributed to pilots from four distinct types of flight operations: General Aviation, 
Regional/Commuter Airlines, Major Airlines and Military Pilots. In total, 4375 surveys 
were distributed; 738 were returned, of which 710 were sufficiently complete to be 
included into the data set. Table 2.5 details the distribution and responses for each type 
of operation. 









Distribution 


Responses 


General Aviation 






2000 


242 


Commuter Airlines 






1075 


114 


Major Air Carriers 






800 


230 


Military (Large A/C 


Based 


in US) 


500 


124 



Total 4375 710 

Table 2.4 - Distribution and Response Rate 



Surveys were distributed to 2000 General Aviation pilots through a commercial 
mailing list Because many of the questions dealt specifically with PLI elements 
available during flight under Instrument Flight Rules, all of these pilots held an 
Instrument Flight Rating. The surveys were distributed equally between 1000 pilots with 
Private Airplane ratings and 1000 pilots with Commercial Airplane ratings. 

Surveys were distributed to pilots of 17 Commuter/Regional Airlines and 4 Major 
Air Carriers through the flight safety officers of the Air Line Pilots Association for each 
airline. 

Military pilots were surveyed by batch mailings to domestic Navy and Air Force 
Squadrons that flew transport or heavy aircraft. These squadrons were selected to avoid 
any responses that may be skewed by highly specialized operations or by pilots who did 
not regularly operate in domestic airspace. 

The distribution was spread, to the extent possible, over the continental United 
States to avoid any effects specific to one geographic area. 



17 



2.3 Data Analysis 

The analysis method of the survey data varied between the different types of 
survey questions. For all numerical ratings, the data was summarized and tested using 
standard statistical techniques. The responses to free-response questions were 
categorized, with the number of similar responses tallied. Variations between responses 
of pilots from different flight operations were determined by examining the responses of 
the different groups separately and testing for differences between them as appropriate. 

The statistical values calculated and the statistical tests used are summarized in 
this section, for both the numerical ratings and the free response questions. 

2.3.1 Analysis of PLI Importance, Availability and Accuracy Ratings 

The ratings of each PLI element were summarized by finding the mean value, 
standard deviation, coefficient of variation and total number of pilots providing a rating 
for that element. Any ratings that the pilot purposely omitted were not included in 
calculating these values. In addition, the number of responses at each particular value 
was tallied. The percentage of responses at each value was formed by comparing these 
tallies to the total number of responses returned. Because not all pilots gave ratings to 
each element, these percentages may not sum to 100%. The same analysis was also used 
for the combined ratings of all PLI elements within a specific Phase of Flight. 

To examine the variations in ratings between pilots with different characteristics, 
the data sets were also subdivided into sets of responses from particular pilot groups. 
These groups were: General Aviation pilots, Commuter Airline pilots, Major Airline 
pilots and Military pilots. Within these subdivisions the mean values, standard deviations 
and counts of specific responses were calculated. 

The PLI elements listed in this survey were chosen for their likely importance to 
pilots. As a result, many of the elements received very high importance ratings causing 
the distribution shape of the responses to be skewed to the higher values. Because this 
distribution is discrete and not normal, the importance of each element can be described 
by the percentage of high importance ratings it receives, in addition to its mean rating. 

The importance ratings were defined on a scaled from '1' (Trivial) to '5' (Critical). 
In this paper, an element is described as Critical if a majority of the pilots gave it an 
importance rating of '5'. However, in addition to the PLI elements which received such 

18 



a clear-cut Critical rating, many other elements received high importance ratings. By its 
position in this interval scale, a rating of '4' can be interpreted as Important but not 
Critical. Therefore, an element is described in this paper as Important if a majority of the 
pilots give it a rating of either '4' or '5'. 

Several statistical tests were conducted to examine the specific variations between 
responses. The first test, an unpaired t-test, calculated the test statistic Z between two 
samples of ratings as follows: 



Z = 



X-Y 




where: 

X = First Sample Mean Y = Second Sample Mean 

S x = First Sample Variance S Y = Second Sample Variance 

n x = Number of Responses in Sample X n Y = Number of Responses in Sample Y 

(Ref. Hogg & Ledolter, 1992) 

The unpaired t-test is exact only for data with a normal distribution. Because the 
ratings given were discrete and skewed towards more important values, a second 
statistical test not assuming a normal distribution was also conducted. This non- 
parametric test, a variation on the Wilcoxon rank-sum test, calculated a test-statistic 
comparing the distribution of two data samples. This test was less specific than the t-test 
for different means because the distributions can differ by having either significantly 
different shapes of distributions or significantly different means. Therefore, results from 
this test had to be carefully examined to determine how the distributions differed and if 
the means were significantly different. 

This test sorts both samples together to generate the overall ranks, in the 
combined sample, for each of the values. The average rank of the values from each of the 
samples is then calculated and compared. The final test statistic Z is calculated as 
follows: 



19 



2 = R x ~ R Y 



i \ \n Y +n Y +1 



where: 

R x = Average Rank of Values in Sample X R Y = Average Rank in Sample Y 
n x = Number of Values in Sample X n Y = Number of Values in Sample Y 

(Ref. Siegel, 1990) 

These two tests generally identified the same significant differences between data 
sets. Because the distribution of responses on scales with only five discrete values is not 
normal, only the non-parametric test can be considered to be exact. However, because 
the number of values in all the data sets was normally quite large (ranging from 100 to 
over 600 responses), despite most subdivisions, the unpaired t-test provided a near exact 
approximation. 

Although the paired-sample t-test could take advantage of the natural blocking 
inherent in comparisons between ratings made by the same people, the nature of the 
survey design degraded the accuracy of this test. Because pilots were asked to rate only 
the elements relevant to their operations, many specific ratings were not given by 
individual pilots and the pairings were inconsistent. 

These statistical tests generated a 'test statistic'. This statistic was then compared 
against the reference value corresponding to the desired confidence level, as shown in 
Table 2-6. A magnitude of the test statistic bigger than the reference value identified a 
statistical difference between the means of the two samples of ratings being compared, at 
the confidence level of the reference value. If the test statistic was less than the reference 
values, then no difference could be concluded at that confidence level and the ratings 
were judged to be the same. A confidence level of (p<0.01) was nominally used. 

Hypothesis Test Level Test Value 

p<.10 1.645 

p<.05 1.960 

p < .01 2.576 

p < .001 3.291 

Table 2.5 - Reference Values Identifying Significant Differences Between Sample 

Means for Desired Test Level 
(ref. Hogg & Ledolter, 1992) 

20 



2.3.2 Subjective Responses 

The free-response questions often provoked detailed responses from pilots. These 
were studied to identify common categories of responses. Then, the number of responses 
in each category was tallied. Pilots often described several items and therefore the 
response from a single pilot could be counted in several categories. 

These responses were also subdivided by the pilots' characteristics to study 
variations between different pilot groups. The counts of responses category were also 
found for each of these subdivisions and then compared. However, for free-response 
questions like these, exact significance testing of the variations is not possible. 



21 



Chapter Three 

Importance, Availability and Accuracy Ratings of PLI 

Elements 



The survey asked pilots for numerical ratings of the Importance, Availability and 
Accuracy of specific PLI elements, in order to develop a quantified evaluation of PLI use 
and perceived importance. This chapter will examine the Importance, Availability and 
Accuracy ratings given to PLI information. The high overall rating of PLI importance 
and the identification of Critical and Important PLI elements is discussed. The strong 
correlation between the Availability and Accuracy ratings is described. Finally, the 
relationship between the elements' Importance ratings and the Availability and Accuracy 
ratings is analyzed. 

Later chapters will further analyze these ratings. The comparative ratings of PLI 
between different phases of flight are discussed in Chapter 4. Then, the variations in PLI 
ratings between pilots from different flight operations are examined in Chapter 5. A 
complete listing of the overall ratings is given in Appendix C. 



22 



3.1 Importance Ratings 

The perceived importance pilots place upon PLI is demonstrated by the high 
ratings pilots gave most PLI elements on a scale from ' 1 ' (Trivial) to '5' (Critical). This 
importance will be examined in two ways. First, the average importance rating given to 
all PLI elements combined will be examined. Then, the importance ratings of the specific 
elements will be studied to identify information elements pilots indicate are Critical or 
Important. 

3.1.1 Overall Importance Rating 

The pilots' high overall rating of PLI demonstrates the importance they give the 
PLI elements listed in the survey. The Critical rating -- the value '5' -- was given 42% of 
the time and the next highest rating was given in an additional 28% of the responses, 
generating a high average rating of 3.97 for all elements combined. The individual 
elements were also rated highly. While the ratings for the elements range from 2.40 to 
4.83 on the 1 (Trivial) to 5 (Critical) scale, most of the mean ratings were above 4.00 and 
many of the elements were judged to be Critical by a majority of the pilots. 

3.1.2 PLI Elements Rated Critical in a Majority of Responses 

Many of the PLI elements in the survey were rated as Critical by the pilots in at 
least one phase of flight, indicating a strong consensus among pilots that these elements 
are vital for flight operations. Table 3-1 lists these elements with the phases of flight in 
which these Critical ratings were given. 

The PLI elements rated as Critical tend to apply to traffic and weather situations 
which directly affect flight safety. The Traffic PLI elements refer to knowledge required 
for collision avoidance ~ Aircraft on Landing Runway, Traffic Avoidance, Traffic - 
Controlled Airports and Traffic - Uncontrolled Airports -- and these elements are 
considered Critical in all applicable Phases of Flight. The highest rated weather elements 
refer to hazards to flight safety ~ Windshear, Missed Approach - Weather, Visibility 
& Ceiling during Terminal Area operations and Final Approach, and Thunderstorms in 
all Phases of Flight. 



23 



Element 


Phase of Flight 


Rating 
Average 


% Pilots Giving 
5 (Critical) Rating 


Aircraft on Landing Runway 


Final Approach 


4.83 


86% 


Traffic - Uncontrolled Airports 


Departure 
Descent 
Terminal Area 
Final Approach 


4.61 
4.51 
4.62 
4.61 


71% 
68% 
72% 
75% 


Traffic - Controlled Airports 


Departure 
Descent 
Terminal Area 
Final Approach 


4.48 
4.47 
4.62 
4.58 


60% 
63% 

71% 
72% 


Traffic Avoidance 


Cruise 


4.35 


57% 


Windshear 


Final Approach 


4.76 


81% 


Missed Approach - Weather 


Final Approach 


4.62 


70% 


Visibility & Ceiling 


Terminal Area 
Final Approach 


4.44 
4.62 


59% 
68% 


Thunderstorms 


Ground Operations 
Departure 
Cruise 
Descent 
Terminal Area 
Final Approach 


4.20 
4.45 
4.44 
4.53 
4.52 
4.25 


52% 
58% 
56% 
61% 
64% 
57% 


Surface Winds 


Final Approach 


4.48 


62% 


Braking Action 


Final Approach 


4.42 


56% 


Icing Conditions 


Departure 
Descent 
Terminal Area 


4.26 
4.28 
4.29 


50% 
50% 
53% 


Aircraft Crossing Active Runway 


Ground Operations 


4.42 


63% 


Approach Clearance 


Terminal Area 


4.47 


62% 


Terminal Routing 


Terminal Area 


4.35 


52% 


Missed Approach - Other 


Final Approach 


4.27 


50% 


Error of Controller 


Ground Operations 
Terminal Area 
Final Approach 


4.38 
4.33 
4.41 


57% 
56% 
61% 



Table 3.1 - Critical PLI Elements 



24 



Several other PLI elements were perceived as Critical, although without as strong 
a consensus. These include other Traffic PLI elements useful for tactical and strategic 
planning, such as Terminal Routing and Approach Clearance, as well as other Weather 
PLI elements useful when planning an approach to landing, such as Surface Winds 
during Final Approach. In addition, Error of Controller was considered Critical during 
the busy phases of flight Ground Operations, Terminal Area and Final Approach. 

3.1.3 Other Elements Rated as Important by a Majority of Pilots 

In addition to the PLI elements which were rated as Critical, many elements 
received Important ratings from the majority of the pilots. The elements with ratings in 
this Important range are listed in Table 3.2 with the Phases of Flight in which these 
ratings were received. 

Many of these elements contain Traffic information useful for anticipating flight 
routings and delays. Examples include Holding Situation/EFC Validity, Relative 
Sequencing, Taxiway Turnoff and Routing to Runway (for Departure). 

The element Weather Overall received ratings within this range for all Phases of 
Flight Most of the specific weather elements also received ratings in this range for the 
Phases of Flight during which they are not considered Critical. For example, Visibility & 
Ceiling received Critical ratings for the Phases of Flight in which the landing approach is 
planned and executed, but during other Phases of Flight ~ Ground Operations and 
Descent — its ratings decreased to fall within this Important range. The variance of 
weather elements' importance ratings with Phase of Flight is analyzed more completely in 
Chapter 4. 

The element Error of the Controller also showed the pattern of receiving 
Important ratings during the Phases of Flight during which it was not considered Critical 
— Departure, Cruise and Descent. Next Communications Frequency was rated 
Important only in the Phases of Flight preparing for approach and landing — Descent, 
Terminal Area and Final Approach. 



25 



Element 
Holding Situation/EFC Validity 


Phase of Flight 
Descent 
Terminal Area 


Rating 
Average 

4.28 

4.19 


% Important 
or Critical Ratings 
84% 
81% 


Relative Sequencing of Other A/C Ground Operations 

Departure 
Cruise 
Descent 
Terminal Area 
Final Approach 


3.66 
3.78 
3.52 
3.96 
4.16 
4.06 


55% 
63% 
54% 
74% 
82% 
77% 


"Hold Short" of Rwy- 


• Other A/C Ground Operations 


3.96 


69% 


Taxiway Turnoff 




Final Approach 


3.67 


57% 


Routing to (Take-Off) Runway 


Ground Operations 


3.60 


57% 


Weather Overall 




Ground Operations 
Departure 
Cruise 
Descent 
Terminal Area 
Final Approach 


3.75 
3.88 
3.87 
4.01 
4.08 
3.87 


63% 
69% 

67% 
74% 
78% 
67% 


Visibility & Ceiling 




Ground Operations 

Departure 

Descent 


3.79 
3.41 
4.12 


65% 
51% 
76% 


Ride Reports & Turbulence 


Departure 
Cruise 
Descent 
Terminal Area 
Final Approach 


3.73 
3.89 
3.70 
3.65 
3.52 


61% 
69% 
60% 
57% 
56% 


Surface Winds 




Ground Operations 
Descent 
Terminal Area 


3.61 
3.79 
4.27 


55% 
67% 
81% 


Icing Conditions 




Ground Operations 

Cruise 

Final Approach 


4.09 
4.19 
4.09 


74% 
80% 
74% 


Error of Controller 




Departure 

Cruise 

Descent 


4.23 
4.01 
4.19 


79% 
69% 
77% 


Next Communications Frequency 


Descent 
Terminal Area 
Final Approach 


3.64 
3.86 
3.59 


59% 
68% 

57% 



Table 3.2 - Important PLI Elements 



26 



3.1.4 PLI Elements Receiving Lower Importance Ratings 

A small group of elements - five elements, some in several Phases of Flight - 
received ratings from the majority of pilots at or below the mid-point value of '3', 
indicating pilots generally consider these elements, at some stages of the flight, to be 
relatively unimportant. These elements, and the Phases of Flight for which they received 
low ratings, are listed in Table 3.3. 







Rating 


# Pilots Giving A 


Element 


Phase of Flight 


Average 


Rating At or Below '3' 


Winds Aloft 


Ground Operations 


2.67 


79% 




Departure 


2.89 


75% 




Cruise 


3.22 


61% 




Descent 


2.64 


78% 




Terminal Area 


2.52 


77% 




Final Approach 


2.40 


77% 


Next Comm. Freq. 


Ground Operations 


2.80 


69% 




Departure 


3.42 


50% 




Cruise 


3.34 


52% 


Ride Report & Turbulence Ground Operations 


3.37 


53% 


Visibility & Ceiling 


Cruise 


3.15 


58% 


Surface Winds 


Departure 


3.00 


62% 




Cruise 


2.54 


74% 



Table 3.3 - Elements Rated Below the Mid-Point Score by a Majority of Pilots 



The element Winds Aloft received low ratings for all Phases of Flight, indicating 
a pilot consensus on the consistently low importance of this element. The other elements 
received these low ratings only in specific Phases of Flight; their variance between POF 
is documented in Chapter 4. 



27 



3.1.5 Importance Ratings of PLI Elements Not Specific to Phase of Flight 

The importance ratings given to the nine Prosodic and General PLI elements are 
shown in Table 3.4. Two elements, Call Sign Confusion and ATC Problems / Lost 
Communication, are considered Critical by all the pilots. The remainder are considered 
Important. Pilots, therefore, perceive the information presented by the method of voice 
communications to be important. 





Rating 


% Pilots Giving 


% Pilots Giving 


Element 


Average 


Important Rating 


Critical Rating 


Call Sign Confusion 


4.53 


91% 


64% 


Controller's Competence 


4.32 


88% 


48% 


ATC Problems / Lost Comm. 


4.38 


87% 


53% 


Navaid Problems 


4.17 


79% 


44% 


Sector Congestion 


3.93 


74% 


22% 


Other Pilot's Competence 


4.00 


72% 


35% 


Controller's Experience 


3.85 


69% 


26% 


Background Transmission 


3.61 


59% 


21% 


Other Pilot's Experience 


3.57 


55% 


19% 



Table 3.4 -- Importance Ratings of General and Prosodic PLI Elements 



28 



3.2 Availability and Accuracy Ratings 

The ratings of all PLI elements combined for Availability and Accuracy indicate 
pilots consider PLI to be generally present and reliable as an information source. The 
Availability ratings scale was defined from T (Non-Existent) to 4 5' (Common-Place); 
the Accuracy ratings scale was defined from ' 1 ' (Unreliable) to '5' (Reliable). The 
overall Availability average of 3.64 and the Accuracy average of 3.81 are significantly 
less than the overall Importance average (p<.01). 

Unlike the Importance ratings where the extreme rating of '5' was common, 
pilots generally did not give the maximum value for the Availability and Accuracy 
ratings. The range between their high and low average ratings is smaller than for the 
Importance ratings. The mean Availability ratings for specific PLI elements range from 
2.63 to 4.35 and the mean Accuracy ratings range from 3.14 to 4.25. 

Two notable features of the Availability and Accuracy ratings do merit 
discussion. First, a strong linear correlation exists between the Availability and Accuracy 
ratings. Second, almost all of these ratings have a strong correlation with the 
corresponding Importance ratings, although the Availability and Accuracy ratings for 
some PLI elements are disproportionally low or high compared to their Importance 
ratings. This section will detail these correlations and discuss their implications. 



29 



3.2.1 Correlation Between Availability and Accuracy Ratings 

A strong linear correlation exists between the Availability and Accuracy ratings, 
with a high correlation co-efficient of .95 and no significant outliers, as shown in Figure 
3. 1. The Accuracy ratings have a higher average overall, but lower range; Availability 
varies more widely around a lower overall value. This strong correspondence may be an 
indication of an increased accuracy of PLI for referencing elements which are commonly 
available, or may be the result of pilots combining the two ratings together to form a 
vague 'Quality' measure. 



G 

'•tod 



« 

> 
< 

OS 

« 

4) 

> 
< 




Average Accuracy Rating 



Figure 3.1 Linear Correlation Between the Availability and Accuracy Ratings 



30 



3.2.2 Correlation Between Importance Ratings and Availability or Accuracy Ratings 

A scatter plot of the elements Importance and Availability ratings is shown in 
Figure 3.2. Because of the strong relationship between the Availability and Accuracy 
ratings, a scatter plot of the Importance and Accuracy ratings is similiar and therefore is 
not shown. 





5 - 






B / 








tog 


q/b 








13 


B 


mrip JR| SB 




ex 






BfA 


est 




'•tai 


4 - 


a 




D 




OS 






wja 










/q" 


B°J Q 




S 






□ 


B B 




<-< 












u 




/ H 








o 
a. 


3- 


/ B 








B 








Q 




** 




y^B 








9) 




M B 








OX) 




JB 








a 












u 












a> 












> 












< 


2 - 

■4 












1 - 


1 1 




1 ■ 





12 3 4 5 

Average Availability Rating 

Figure 3.2 -- Importance Ratings Compared to Availability Ratings for All PLI 

Elements 

These ratings for all the elements do not show a strong correlation. However, the 
PLI elements can be divided into three groups by observation: 

• The majority of elements, which have a strong correlation 
between their Importance and either their Availability or their Accuracy 
ratings. 



31 



• Elements with high Availability and Accuracy ratings and low 
importance ratings -Next Communications Frequency, Controlled 
Traffic, Approach Clearance, Terminal Routing and Surface Winds 

(Final Approach only). These ratings may represent items which are 
continuously presented by PLI. 

• Elements with low Availability and Accuracy ratings but high 
Importance ratings - Error of the Controller and Uncontrolled Traffic. 

Their relatively low Availability and Accuracy ratings may indicate they 
are specific information elements for which pilots feel PLI is not an 
adequate information source. 

These groups were verified statistically by comparing the actual Availability and 
Accuracy ratings to the values expected by a linear line of best fit with the corresponding 
Importance ratings. 



32 



Chapter Four 

Variation in Party Line Information Importance 
Between Phases of Flight 



Throughout the different phases of flight, the pilot's requirements for PLI may 
change considerably. Several factors contribute to these changes: the differences in 
weather conditions between high-level cruise and low-altitude airport operations, the 
transitions between control by different Air Traffic Control facilities, and changes in the 
type of decisions required of the pilot, in the time-critical nature of the decisions, and in 
pilot workload. 

In Midkiff s survey, significant differences were found in the Importance ratings 
given to the collected Party Line Information (PLI) elements both separately and 
averaged together within each phase of flight. Similar trends in the PLI importance, 
availability and accuracy ratings were found by this survey. 

This chapter will first discuss the characteristics of each Phase of Flight as they 
were defined in this study. Then, the effects these Phases of Flight have on the PLI 
Importance ratings is examined in two ways, by comparing the ratings of all PLI elements 
in each Phase of Flight combined and by examining the variations in the ratings for each 
specific element between each Phase of Flight. The trends of the Availability and 
Accuracy ratings are nearly identical to those shown by the importance information and 
therefore are not described separately. The Importance Ratings given in each Phase of 
Flight are listed in Appendix D. 



33 



4.1 Flight Operations Throughout All Phases of Flight 

A normal flight can be divided the sequential Phases of Flight shown 
schematically in Figure 4.1. The differences between Phase of Flight relate both to the 
different conditions the aircraft experiences in each and to the variations in the pilot's 
duties and workload. This section will detail the definitions of each Phase of Flight used 
by this survey, and then will examine the characteristic differences between them that are 
relevant to PLI use and importance. 



Enroute Control 
(CbMir) ; ; 




Cruise 



■v 

- u 



Descent 

Top of Descent to 
Approach Control Handoff 



Departure 

Take-Offto Top of Climb 




^k Approach Control 



Terminal Area 



Towmr 



a-CT ^woKOMwawewMcwHw: 



Final Approach 

Approach Fix to Landing 



*^^^^^^^^^svsfi; 




Figure 4.1 Normal Flight Sequence 



34 



4.1.1 Descriptions of Each Phase of Flight 

A definition of each Phase of Flight was given to the pilots in this survey by the 
points during flight delineating its beginning and ending. These definitions and a brief 
description of each Phase of Flight are give here. 

Ground Operations 

This Phase of Flight was defined to include Dispatch, Pre-Start & Taxi. The pilot 
is presented with PLI during this phase from the time the first radio frequency is 
monitored until take-off. Depending on the departure airport, the pilot may monitor 
several frequencies, including the ATIS, ramp control, clearance delivery and ground 
control frequencies. The pilot's duties include planning the flight route, gathering and 
updating information needed for the flight, preparing the aircraft systems for flight and 
taxiing the aircraft. 

Departure 

This Phase of Flight was defined to span from Take-Off to Top of Climb. It can be 
further divided into three distinct segments. During the first, the take-off, the pilots full 
attention is given to controlling the aircraft. Then, during the initial climb, the pilot 
follows steering vectors away from the terminal area. Finally, during the cruise climb the 
pilot and autopilot systems navigate and plan ahead for cruise. The pilot will 
communicate first with the tower controller, then with the Terminal Area departure 
controller, and finally will transition to an Enroute Control Center. 

Cruise 

This Phase of Flight is defined to last from Top of Climb to Top of Descent. This 
is usually the longest phase with the least variance in pilot tasks. Generally, the pilot and 
the aircraft flight systems follow a nearly level and straight course for most of the 
duration of the flight. The pilot also executes any deviations from the given course due to 
weather or traffic congestion, and plans ahead for the descent and landing. As the 
aircraft's position changes, the pilot is passed on to successive Enroute Control Centers. 



35 



Descent 

The survey defined this Phase of Right as from Top of Descent to Approach 
Control Contact. During this phase the aircraft transitions from its established cruise 
flight path to a lower altitude where the aircraft is vectored by ATC into position for 
arrival at the Terminal Area. The pilot must plan ahead for the approach and for any 
delays and must steer the aircraft as commanded by ATC. The aircraft remains under the 
supervision of a Enroute Control Center. 

Terminal Area 

This Phase of Flight was defined as from Approach Control Contact to the Final 
Approach Fix and spans most of the time during which the aircraft is supervised by the 
Terminal Area's approach controller (TRACON). Although this phase is shorter than 
those preceding, the pilot has many duties requiring immediate attention. In addition to 
preparing for the final approach, the pilot must also steer the aircraft, as commanded by 
ATC, for traffic and weather avoidance, holding, and sequencing. 

Final Approach 

This Phase of Flight was defined as from Final Approach Fix to Runway 
Threshold. Especially during adverse weather conditions, the pilot's attention is directed 
to the safe execution of the final approach and landing. Normally, the planning of the 
approach is complete before it is started; the pilot's attention is reserved during this phase 
for its execution. ATC control of the aircraft will transfer during the approach from the 
approach controller to the airport's tower control. 



36 



4.1.2 Changes in Flight Characteristics Between Phase of Flight 

In addition to the clearly defined changes in the duties required of a pilot during a 
flight, several other characteristics of the flight change with POF. These characteristics 
are both physical conditions affected by the changes in altitude and airspace, and also the 
less tangible demands placed upon the pilot. 

The most obvious physical changes are the changes in weather conditions caused 
by the ranged of altitudes covered in a normal flight. Some conditions, such as 'Surface 
Winds' and "Visibility & Ceiling' are predominantly low-level conditions. Other weather 
conditions, such as 'Winds Aloft', are found specifically at cruise altitude. An aircraft's 
exposure to the different weather conditions then varies with the altitude of the aircraft. 
This exposure is also partially determined by the length of time for which the aircraft is at 
that altitude. For example, an aircraft departing an airport can climb through altitudes 
where uncomfortable turbulence is prevalent enough to discourage long-distance cruise. 

During the airborne section of the flight, the aircraft passes through three distinct 
types of airspace: the local Tower' control immediately surrounding the airport, the 
'Terminal Area' Control (TRACON) extending around the airport area to a distance of 
about 50nm, and the 'Enroute Center' covering the high-level cruise and areas between 
airports. Because these transitions generally include moving from 'less crowded' to 
'more crowded' airspace during arrival into an airport, several other changes can occur. 
The voice frequency itself can become 'congested', with nearly continuous transmissions. 
The traffic situation can change so that the routing of the flight becomes dependent on 
sequencing of the aircraft to ensure their separation. In congested airspace, especially 
near busy airports, traffic watch and collision avoidance become vital concerns. 

The nature of the tasks required of the pilot also change in several ways 
throughout flight. During the early stages of the flight, the pilot is responsible for short 
and long-term strategic planning of the complete flight path based upon the his or her 
estimates of the future conditions. As the aircraft nears the destination the time span over 
which the pilot must make these estimates and plan the flight path shortens. Once in the 
busier terminal area, the pilot's task changes to immediate tactical planning while being 
vectored by the air traffic controller into position for the approach, and to preparing for 
the approach. By the time the pilot is established on Final Approach, a majority of 
planning is done and he/she is primarily concerned with controlling the aircraft. 



37 



Many other factors follow this trend of increased severity nearer the airport. For 
example, the time pressure placed upon the pilot to analyze information and make 
decisions increases nearer the airport (ref. Hart, Hauser & Lester, 1984). During Cruise 
the pilot is normally free to consider and compare information. In contrast, during Final 
Approach the time available to make decisions such as a missed approach is often 
reduced to seconds. 

Another condition which has been widely studied is pilot workload. Studies show 
that pilot workload follows a distinct trend of being the lowest during Cruise and the 
highest during Terminal Area and Final Approach. (Ref. Hart, Hauser & Lester, 1984). 
With this change in workload may come a change in the capability of the pilots to 
disseminate PLI. Results from an experimental simulator study suggest that, during high 
workload conditions, analyzing PLI becomes a lower priority activity compared to more 
immediate concerns such as completing an approach. (Ref. Midkiff, 1992) 



38 



4.2 Overall Variance of PLI Importance with Phase of Flight 

An overall comparison of the perceived variations of PLI importance between 
different Phases of Flight was made by comparing the combined ratings of all PLI 
elements listed with each, as shown in Figure 4.2. The highest ratings were given to the 
Phases of Flight nearest the airports, especially Final Approach, where a majority of the 
ratings were Critical, and Terminal Area. The lowest importance ratings are given in 
Cruise , where only 30% of the ratings were Critical. The ratings for each successive 
Phase of Flight are significantly different from the one preceding (p < 0.01), except 
between the ratings for Final Approach and Terminal Area. 



100% 

5 90% 
g 80%-- 
§. 70%-. 

6 60% 
•S 50% - - 
& 40% - - 
I 30% - - 
g 20%-- 
£ 10% 




Ground Departure 
Operations 



Cruise Descent Terminal 

Area 



Final 
Approach 



D % Important Ratings H % Critical Ratings 



Figure 4.2 « Combined Importance Ratings of AH PLI Elements for Each Phase of 

Flight 



These combined ratings within each Phase of Flight mark a general pattern in PLI 
importance: significantly lower ratings given in Cruise, higher ratings in Terminal Area 
and Final Approach. However, these combined ratings may be biased somewhat because 
the list of PLI elements with each Phase of Flight was set during the survey design. 
Therefore, some Critical elements received ratings with specific Phases of Flight, raising 
the combined ratings for those Phases of Flight. 



39 



4.3 Variance of Weather PLI Importance with Phase of Flight 

The importance ratings given to the individual weather PLI elements in each 
Phase of Flight was classified in several patterns. Weather Overall followed the same 
pattern as shown by the combined PLI ratings with lower ratings in Cruise and higher 
ratings on Final Approach. The specific weather elements had particular Phases of Flight 
during which each element is particularly important. 

This section will detail these trends and will identify the Phases of Flight during 
which the individual elements are of particular importance to pilots. The correspondence 
between the trends for the elements and those predicted by the characteristic tasks of the 
pilot in the Phases of Flight will also be discussed. 

4.3.1 Variance of Weather Overall 

The importance ratings of the PLI element Weather Overall varies throughout 
the Phases of Flight with a pattern of lower importance ratings in Cruise and higher 
importance ratings in Terminal Area, as can be seen in Figure 4.3. The element is 
considered Important for all POF and this perceived importance increases for the Phases 
of Flight nearer the conclusion of the flight. 



40 



c 
o 
a, 

o 
u 

c 
u 

a 



100% 
90% 
80% 
70% 
60% 
50% 
40% 
30% 
20% 
10% 
0% 




mmmmmm, 








^ 



^1. 



&0 



£g^£ 



Ground Departure 
Operations 



Cruise Descent Terminal Final 

Area Approach 



El % Important Ratings D % Critical Ratings 



Figure 4.3 - Importance Ratings of Weather Overall for All Phase of Flight 



The importance of Weather Overall differs from the general PLI pattern in two 
ways. First, the percentage of pilots giving this element an Important rating drops 
significantly from Terminal Area to Final Approach, although the percentage of pilots 
giving it a Critical ratings stays the same. This particular discrepancy may indicate a 
lower need of a pilot to gather weather information on Final Approach to plan ahead 
because the approach is already planned by the time it is started, and because the 
approach and landing complete the flight. 

Second, the importance ratings in Cruise are not significantly lower than those 
for Ground Operations and Departure. These similar ratings may result from the duties 
of the pilot during Cruise. Even during high-level, long-range cruise, the pilot must 
monitor any weather conditions that can indicate the most efficient and safe routing and 
flight level of the aircraft and the pilot must update the estimate of weather conditions at 
the destination as it becomes available. 



41 



4.3.2 Weather PLI Elements Consistently Important for All Phases of Flight 

Two elements -- Thunderstorm Buildups and Deviations and Icing Conditions 

were consistently perceived to be Important and Critical in almost all Phases of Flight, as 
shown in Figures 4.4 and 4.5. The importance ratings for these elements were always 
very high, especially during Descent and Terminal Area. While still very important, the 
ratings for Ground Operations and Final Approach were significantly lower than for the 
other Phases of Flight 




Ground Departure Cruise 
Operations 



E » 1 
1 liiOl 



Descent Terminal 

Area Approach 



EI % Important Ratings H % Critical Ratings 



Figure 4.4 -- Importance Ratings of Thunderstorm Buildups and Deviations 



42 



The ratings of Icing Conditions are shown in Figure 4.5. They followed the 
same trend as Thunderstorms and Deviations but received fewer critical ratings. 




Ground Departure Cruise 
Operations 



Descent 



Terminal Final 
Area Approach 



HJ % Important Ratings H % Critical Ratings 



Figure 4.5 -- Importance Ratings of Icing Conditions 



43 



4.3.3 Weather PLI Elements Rated Lower in Cruise, Higher on Final Approach 

The importance ratings of two weather elements, Visibility and Ceiling and 
Surface Winds, follow a marked pattern of lower ratings in Cruise and very high ratings 
in Final Approach, as shown in Figures 4.6 and 4.7 During Departure and Cruise, the 
ratings of these elements are low enough to not be considered Important by a clear 
majority of the pilots. The importance ratings increase steadily through Descent, 
Terminal Area and Final Approach such that they are perceived to be Critical in both 
Terminal Area and Final Approach. 

The Critical ratings of these elements on Final Approach can be explained by 
their importance to the pilot as vital factors in determining the success of executing an 
approach to land. Although they may be important at other times during the flight, during 
Final Approach these elements can be deciding factors in the execution and completion 
of the approach and landing. Their Important ratings during Descent and Terminal Area 
likely indicate the desire of the pilot to plan ahead for the approach and landing. During 
Cruise, in comparison, these low-level weather conditions are not very relevant to the 
immediate flight operations and are only of interest in planning ahead for the landing. 



44 



100% -r 





90% 


tfl 


80% 


C/5 

c 

a 

U 

o 


70% 
60% 
50% 


2 


40% 




30% 


4> 


20% 




10% 




0% 



C/3 

<u 

1/3 

e 
o 

U 

O 

0> 

c 

a 

u 

Oh 




Ground Departure Cruise 
Operations 



Descent Terminal Final 
Area Approach 



H % Important Ratings M % Critical Ratings 



Figure 4.6 -- Importance Ratings of Visibility & Ceiling 



100% 
90% 
80% 
70% 
60% 
50% 
40% 
30% 
20% 
10% 



„„ . i t , „„„ ., : 






Ground Departure Cruise Descent Terminal Final 
Operations Area Approach 

□ % Important Ratings U % Critical Ratings 
Figure 4.7 - Importance Ratings of Surface Winds 



45 



4.3.4 Elements Rated only for Final Approach 

Two elements were relevant only to Final Approach - Missed Approach - 
Weather and Windshear. These elements were both rated as very important - 81% of 
the responses for Windshear and 70% of the responses for Missed Approach - Weather 
were Critical - indicating the pilots' perception that these elements are vital for executing 
a safe approach and landing. 

The element Windshear is a phenomenon applicable to any low-flying aircraft. 
Although it was not included in Departure, several pilots noted this oversight and added 
Windshear to the PLI element list for this Phase of Flight, with corresponding Critical 
ratings. 



4.3.5 PLI Weather Elements With the Highest Importance During Cruise 

As shown in Figures 4.8 and 4.9, two weather elements, Ride Reports & 
Turbulence and Winds Aloft, received the highest ratings in Cruise and significantly 
lower ratings in all other phases. These importance ratings reflect several aspects of these 
elements. First, these elements did not receive very high importance ratings, even in 
Cruise where they scored the highest. Second, they are conditions that effect the aircraft 
for long periods of time in Cruise. During the Phases of Flight closer to the airport, 
aircraft will be transitioning through the altitudes where these adverse conditions may be 
occurring and so will not be exposed to them for as long. Finally, neither element usually 
affects the safety of a flight except in cases of severe turbulence. During Cruise, 
knowledge of this information can enable the pilot to make changes in flight altitude 
and/or routing that will improve the comfort and efficiency. Therefore, during the busier 
Phases of Flight such as Terminal Area and Final Approach, pilots may tend to disregard 
these PLI elements if they are not severe. 



46 



100% -r 




a 
o 

9< 

*} 

o 
<u 

a 

c 

a 

V 



Ground Departure 
Operations 



Cruise Descent 



Terminal 
Area 



Final 
Approach 



11 % Important Ratings H % Critical Ratings 



Figure 4.8 -- Importance Ratings of Ride Reports & Turbulence 



100% 
90% 
80% 
70% 
60% 
50% 
40% 
30% 
20% 
10% 
0% 











^S 






Ground Departure Cruise 
Operations 



Descent Terminal Final 
Area Approach 



□ % Important Ratings H % Critical Ratings 



Figure 4.9 -- Importance Ratings of Winds Aloft 



47 



4.4 Variance of Traffic PLI Importance with Phase of Flight 

All Traffic PLI elements follow the pattern of receiving greater importance ratings 
during Terminal Area and Final Approach , lower importance ratings during Cruise. 
These Traffic PLI elements can be categorized into two different groups, Traffic 
Avoidance and Traffic Planning. Each will be discussed separately. 

4.4.1 Traffic Avoidance PLI Elements 

The majority of pilots always perceive Traffic Avoidance PLI elements to be 
Critical. These elements follow the general trend of lower importance ratings in Cruise, 
higher ratings nearer the airport, as shown in Figures 4. 10 and 4. 1 1. All responses for 
these elements are considered Critical by a majority of the pilots although the percentage 
of pilots giving this rating varies significantly with Phase of Flight. Traffic - Controlled 
and Traffic - Uncontrolled during Final Approach receive the most Critical ratings and 
the fewest Critical ratings are given to Traffic Avoidance during Cruise . Traffic - 
Controlled and Traffic - Uncontrolled receive very similar ratings, with a significant 
difference between them only during Departure. 

Although the percentage of Critical ratings varies with Phase of Flight for these 
elements, the percentage of Important ratings does not. At least 84% of pilots gave either 
an important or critical rating to these elements for all Phases of Flight with a slight 
increase in the ratings for Terminal Area and Final Approach. Pilots, therefore, always 
feel traffic avoidance information is Important. 

An other Traffic Avoidance PLI element, Aircraft on Runway, is also perceived 
by a very large percentage of the pilots to be Critical. This element was only rated in 
Ground Operations and Final Approach, supporting the trend of increasing importance 
for the Phases of Flight nearer the airport 



48 



100% T 

90% -■- 

£ 80% 

§ 70% 

£ 60% 

*5 50% .- 

& 40% 

§ 30% 

| 20% 

10% 4-- 



o% 



MMfc»* »O i 





Departure Cruise ** Descent Terminal 

Area 



Final 
Approach 



□ % Important Ratings El % Critical Ratings 



Figure 4.10 - Importance Ratings for Traffic - Controlled 
(** Indicates Ratings for the PLI Element Traffic Avoidance in Cruise) 





90% ■ 
80% - 
70% - 
60% - 


-- 























V 

C 

o 

<+-c 

o 










-- 






-- 




. • 


50% ■ 


._ 




■ • • ■ 




a n « ■ 




• — w ■ 








• . 


too 

3 


40% . 


■- 
























-- 


c 


30% - 
20% - 


__ 




_ _ _ _ 




• « _ ■ 




•.*«.. 




. — — — 




.. _ 




10% - 


-- 



















----' 




"- 



Departure Cruise** Descent Terminal 

Area 



Final 
Approach 



□ % Important Ratings H % Critical Ratings 



Figure 4.11 -- Importance Ratings for Traffic - Uncontrolled 
(** Indicates Ratings for the PLI Element Traffic Avoidance in Cruise) 



49 



4.4.2 Traffic Planning PLI Elements 

One Traffic Planning PLI element, Relative Sequencing (of Other Aircraft), 

was given importance ratings in all Phases of Flight, as shown in Figure 4.12. Throughout 
all phases this element was generally considered Important but not Critical by the 
majority of pilots. The ratings in the Descent and Terminal Area generally receive the 
most Important scores, while Cruise receives the least. 



100% T 




Ground Departure 
Operations 



Cruise Descent 



Terminal 
Area 



Final 
Approach 



□ % Important Ratings H % Critical Ratings 



Figure 4.12 - Importance Ratings of Relative Sequencing 



50 



The percentage of Important and Critical ratings give to other Traffic Planning 
PLI elements are shown in Table 4.1. They were each given ratings in only specific POF, 
such as Descent, Terminal Area, and Final Approach. Their high importance ratings in 
these Phases of Flight support the pattern of higher PLI importance near the airport. 



PLI Element 


% Pilots Giving 
Phase of Flight Important Ratine 


% Pilots Giving 
Critical Ratine 


Hold Situation/ 
EFC Validity 


Descent 
Terminal Area 


84% 
81% 


45% 
43% 


Terminal Area Routing 


Terminal Area 


87% 


52% 


Approach Clearance 


Terminal Area 


88% 


62% 


Missed Approach - Other 


Final Approach 


83% 


50% 



Table 4.1 •- Importance Ratings of Other Traffic Planning PLI Elements 



51 



4.5 Other PLI Elements 

The PLI elements such as Error of Controller and Next Communications 

Frequency received ratings following the pattern of the combined PLI elements ~ less 
important ratings during Cruise, more important ratings during Terminal Area and Final 
Approach., as shown for Error of Controller in Figure 4. 13. Unlike the differences in 
ratings found for other PLI elements, however, the differences between the ratings of 
these PLI elements for the different Phases of Flight do not generally test to be significant 
to the (p< 0.01) level. 



100% 
90% 




Ground Departure Cruise 
Operations 



Descent 



ICllIlilldl 

Area 



Final 
Approach 



% Important Ratings E3 % Critical Ratings 



Figure 4.13 -- Importance Ratings for Error of Controller 



52 



Chapter Five 

Variation in PLI Importance Between Flight Operation 

Groups 



Substantial differences in aircraft, flight profiles and operating procedures exist 
between pilots of the different type of flight operations. To study the effect these 
differences have on PLI importance and use, this survey was distributed to pilots from 
four specific flight operation groups: General Aviation, Commuter & Regional Airlines, 
Major Airlines and Military transport operations. 

Many significant differences (p < 0.01) were found between the importance 
ratings of PLI given by pilots from each flight operation group. These differences can be 
classified into two types. First, a pattern of lower PLI importance ratings in Cruise, 
higher PLI importance ratings in Terminal Area and Final Approach is shown by all 
pilots except the General Aviation pilots in the combined ratings of all PLI elements 
within each Phase of Flight. Second, each flight operation group identifed specific PLI 
elements of particular importance to that group. 

The responses were also analyzed to determine if other pilot characteristics, such 
as total flight time, resulted in differences in PLI importance ratings. However, these 
traits were generally found to correlate with the type of flight operation of the pilot and 
could not provide any independent insights. 



53 



5.1 Pilot Characteristics 

This survey was distributed to pilots from four distinct types of flight operations: 
General Aviation, Commuter & Regional Airlines, Major Airline and Military pilots. 

General Aviation includes a broad range of flight operations, from recreational 
private pilots to professional non-scheduled flight charter businesses. As a group, 
however, these pilots tend to fly smaller aircraft with less advanced equipment than the 
other flight operation groups. Their flights often operate at lower cruise altitudes (less 
than 18,000 feet MSL) and span relatively shorter distances. As a result, General 
Aviation is very sensitive to adverse weather conditions. In addition, General Aviation 
aircraft fly more often into smaller airports and have less advanced cockpit 
instrumentation to aid the pilot than other types of civil aviation operations. 

The Commuter & Regional Airline category includes scheduled short-haul 
operations with aircraft ranging in size from twin-engine turboprop aircraft to smaller jet 
airliners. These aircraft often fly into both smaller, uncontrolled airports and major 
terminal areas. Although these aircraft will generally have increased forms of anti-icing 
equipment and weather radar, many do not have the autoflight systems found in the larger 
airline aircraft, and may have limited ground support at some airports. 

Major Airline pilots fly the well equipped aircraft on scheduled routes. All their 
aircraft have substantial equipment for weather detection and traffic avoidance. The 
newest aircraft, such as the Boeing 757, 767, 747-400, MD80, MD1 1 and the Airbus 320 
series, also present the pilot with the electronic or 'Glass' cockpit displays and with 
autoflight systems capable of navigation and auto-landings. These aircraft may travel 
both shorter domestic routes and many hour transcontinental or transoceanic flights, with 
cruise altitudes ranging between 20, 000 feet MSL for shorter flights and 40, 000 feet 
MSL on longer flights. 

The military squadrons to which the survey was distributed were chosen based on 
their domestic flight operations using larger multi-engine aircraft, such as Airlift, 
Transport and Coastal Patrol. Some of their aircraft, such as the KC-135, C-130, C-141 
and DC-9, are similar to those flown by the Major Airline group. 

In addition to surveying for the type of flight operation, the Background 
Information page of the survey requested detailed information about other characteristics 
of the pilot which might affect their perceived importance of PLI. These characteristics 

54 



included items such as: total flight hours, flight hours in the last year and years as a pilot, 
flight ratings held, aircraft flown, geographic region, average length of flight, and 
customary ATC frequency congestion. 

However, most of these characteristics were found to correspond strongly to the 
type of flight operation. For example, as shown in Table 5.1, pilots with the least flight 
experience (as ascertained by Total Flight Hours) were the General Aviation pilots, while 
pilots with the most flight experience were the Major Airline pilots. As a result, the 
differences in the PLI ratings given by low-time and high-time pilots are similiar to the 
differences in the PLI ratings given by General Aviation and Major Airline pilots. 
Therefore, where significant variations in PLI ratings exist between pilots with differing 
characteristics, the differences can generally be correlated to an underlying difference in 
flight operations. 





0-1500 


Fligh 
1500-5000 

28% 

25% 

8% 


t Hours 

5000-10000 

6% 


10000+ 


General Aviation 


64% 


2% 




0% 
0% 

27% 




Commuter Airlines 


48% | 


26% 








Major Airlines 


39% 


53% | 




11% 




Military 


63% 


0% 



| I = Largest Amount of Pilots Within Each Range of Flight Hours 

Table 5.1 -- Comparison Between Respondents' Flight Hours and Type of Flight 

Operations 



55 



5.2 Variations in PLI Importance Ratings in All Phases of Flight 

The relative importance ratings given PLI by pilots from different flight 
operations changes with the different Phases of Flight. The Commuter and Major Airline 
pilots generally gave higher importance ratings for PLI elements in Terminal Area and 
Final Approach and lower importance ratings in Cruise. The General Aviation pilots, on 
the other hand, gave consistently high importance ratings in all Phases of Right. 

This pattern is shown by the combined importance ratings of all PLI elements 
listed in each Phase of Right, as pictured in Figure 5.1. Significant differences exist 
between the ratings given by each type of pilot in each Phase of Flight except Final 
Approach. The largest difference is in Cruise, when all of the pilot types except for 
General Aviation perceive PLI to be significantly less important than the other Phases of 
Flight. In contrast, the General Aviation pilots gave the PLI elements more important 
ratings in Cruise than in Departure and Ground Operations. 



100% -r 



e 

am 

«■> 
OS 






4> 

WD 

a 

■<-> 

e 

4) 
U 

U 
0> 

a. 




Ground Departure 
Operations 



Cruise Descent Terminal Final 

Area Approach 



I General Aviation □ Commuter 

Airline 



I Major Airline 



Military 



Figure 5.1 - Combined PLI Importance Ratings for All PLI Elements in 

Each Phase of Flight 
(Shown for Each Type of Flight Operation) 



56 



The importance ratings of two specific PLI elements also followed this pattern. 
The ratings for the first PLI element, Weather Overall, are shown in Figure 5.2. The 
General Aviation pilots gave fairly consistent ratings for all Phases of Flight. 
Comparatively, the Commuter and Major Airline pilots gave significantly lower ratings 
to this element in Cruise and higher importance ratings in Final Approach and Terminal 
Area. 



(A 
Of) 

c 

'S 

« 

"3 






0> 

OX) 

a 

e 

u 



100% T 

90% ■- 




Ground Departure 
Operations 



Cruise Descent Terminal Final 

Area Approach 



I General Aviation □ Commuter 

Airline 



I Major Airline 



Military 



Figure 5.2 -- Weather Overall Importance Ratings in Each Phase of Flight 
(Shown for Each Type of Flight Operation) 

These relative differences in importance ratings were greater for the PLI element 
Thunderstorm Buildups & Deviations, as shown in Figure 5.3. The General Aviation 
pilots gave this PLI element a significantly higher rating in Cruise, while the Commuter 
and Major Airline pilots gave it a higher rating in Final Approach. The Commuter 
Airline pilots also gave it a higher rating in Departure. 



The observed variation in PLI importance ratings may be explained by the 
characteristics of the different types of flight operations. Unlike the other types of flight 
operations, General Aviation aircraft rarely reach high level cruise for long periods of 

57 



a 

SB 

« 






OS 
OS 

■** 

e 

V 

u 

a. 



100% T 

90% 




Ground 
Operations 



Departure Cruise Descent 



Terminal Final 
Area Approach 



General Aviation □ Commuter 
Airline 



Major Airline 



I Military 



Figure 5.3 - Thunderstorm Buildups Importance Ratings in Each Phase of Flight 
(Shown for Each Type of Flight Operation) 



time but instead normally cruise at lower altitudes where they are more sensitive to low- 
level weather conditions and where they are often in transit through busier low-level 
airspace. Also, they often lack the weather radar equipment standard to the other types of 
flight operations. Therefore, their information requirements may remain consistently 
high throughout the flight, without large distinctions between the different Phases of 
Flight, resulting in their consistently high importance ratings. 

In contrast, the flight operations of the Commuter and Major Airline pilots, and of 

the Military pilots flying larger aircraft, generally involve distinct differences between the 

different Phases of Flight. Because they follow scheduled high-level cruise flight paths, 

they are less susceptible to weather conditions and to immediate route changes. 

However, their operations near the destination can sometimes include a transition to more 

congested airspace, worse low-level weather and scheduling delays or holds. With these 

operational differences these pilots identified specific Phases of Flight, Terminal Area 

and Final Approach, where they perceive PLI to be especially important. 

58 



5.3 PLI Elements Perceived More Important by Major Airline Pilots 

The Major Airline pilots consistently identified the PLI element Ride Reports & 
Turbulence as more important than the pilots of other flight operations, as can be seen in 
Figure 5.4. Except in cases of severe turbulence, this element generally concerns the 
comfort of the passengers on the aircraft and therefore the Military transport aircraft gave 
it the lowest importance ratings, General Aviation pilots the next lowest, and the Airline 
pilots of aircraft the most concerned with a comfortable long-distance cruise gave this 
element the highest importance ratings 



G 






100% T 

90% -- 

i ■■ 

70% 
60% 
50% 



° 40% 

I 30% 




Ground Departure 
Operations 



Cruise 



Descent 



Terminal 
Area 



Final 
Approach 



I GA Critical 



□ Commuter 
Critical 



Airline Critical ■ Military Critical 



Figure 5.4 - Ride Report & Turbulence Importance Ratings in Each Phase of Flight 

(Shown by Each Type of Flight Operation) 



Three other PLI elements, Routing to Runway (for Takeoff), "Hold Short" of 
Active Runway of Other Aircraft and Braking Action, were also rated as significantly 
more important by Major Airline pilots. These elements are relevant to their operations 
from large and busy airports. Braking Action is also a greater concern to Major Airline 
pilots because of their large aircraft which require substantial braking and runway 
distance to slow from landing speed. 



59 



5.4 PLI Elements Perceived More Important by Commuter Airline 
Pilots 

Pilots were asked to rate the importance of the PLI element Traffic Avoidance -- 
Uncontrolled Airports in four Phases of Flight. In the three phases nearest the airport -- 
Departure, Terminal Area and Final Approach - this element was given higher 
importance ratings by the Commuter Airline pilots, as shown in Figure 5.5. In Descent 
this difference in importance ratings is also visible but does not test to be statistically 
different. These higher importance ratings may result from the type of flights common to 
these pilots. Although they generally fly fairly modern turbine-powered aircraft over 
scheduled routes, many of their destinations may be smaller, uncontrolled airports. 



100% -r 



in 

Ml 
C 

X 









0) 

on 

e 
o> 
u 

u 

V 

0- 




Departure 



Descent 



Terminal 
Area 



Final 
Approach 



I General Aviation □ Commuter 
Airline 



I Major Airline 



Military 



Figure 5.5 -- Uncontrolled Traffic Importance Ratings in Each Phase of Flight 
(Shown by Each Type of Flight Operation) 



60 



5.5 PLI Elements Perceived More Important by General Aviation 
Pilots 

Several PLI elements were always rated more important by General Aviation pilots. 
Figure 5.6 shows the percentage of Critical ratings given to Icing Conditions by pilots of 
each flight operation. In all Phases of Flight the ratings given by the General Aviation 
pilots are very high and are significantly higher than those given by at least one other 
group. The ratings are the lowest from the Major Airline and Military pilots. 

This effect can be explained by the differences in their aircraft. Unlike the larger 
aircraft of the Military and Major Airline pilots, General Aviation aircraft generally are 
not certified for flight in known icing conditions and may not be able to climb above 
icing altitudes. Therefore, inflight icing is a condition which General Aviation aircraft 
must avoid by knowing where it may occur. These ratings indicate PLI is perceived as an 
important information source for this element. 



OX) 



CO 

OS 






u 
U 



BX) 

3 
c 

o 

u 

0- 




Ground Departure 
Operations 



Cruise Descent Terminal Final 

Area Approach 



I General Aviation □ Commuter 

Airline 



I Major Airline 



Military 



Figure 5.6 - Icing Conditions Importance Ratings in Each Phase of Flight 
(Shown by Each Type of Flight Operation) 

61 



Figure 5.7 shows the ratings given Visibility & Ceiling by the different types of 
pilots. In all Phases of Flight except Ground Operations the General Aviation pilots gave 
this PLI element significantly higher importance ratings. The differences are the greatest 
in Cruise, where the Commuter Airline, Major Airline and Military groups gave very low 
importance ratings. In the Phases of Right Terminal Area and Final Approach the 
ratings given by the Commuter Airline pilots near those of the General Aviation pilots. 



100% -r 



OJD 

s 
fit 









OX) 

a 

s 
<u 
o 

u 




Ground Departure 
Operations 



Cruise Descent Terminal Final 

Area Approach 



I General Aviation D Commuter 

Airline 



I Major Airline 



Military 



Figure 5.7 -- Visibility & Ceiling Importance Ratings in Each Phase of Flight 
(Shown by Each Type of Flight Operation) 

These differences may be caused by the differences in the aircraft and equipment. 
The high importance ratings by General Aviation pilots in Cruise may result from their 
lower cruise altitudes and limited range which can keep them in Instrument 
Meteorological Conditions for significant portions of their flight Both the General 
Aviation and Commuter Airline pilots may not have advanced capabilities for precision 
approaches and autopilot-approaches available in their aircraft and at the smaller airports 
they may operate out of. Therefore, this PLI element maybe more important to these 
pilots during Terminal Area and Final Approach. 



62 



A third Weather PLI element, Winds Aloft, also received significantly higher 
ratings from General Aviation pilots in all POF, as shown in Figure 5.8. These ratings 
may also result from the characteristics of the General Aviation aircraft. Because these 
aircraft fly at lower airspeeds, this weather condition had a larger effect on their 
performance than on the other groups. 



100% -r 

a 90% 

! 80% -■ 

as 

* 70% 

•H 60% 

U 50% 

® 40% -- 

f 30% 

| 20% 

u 

& 10% 



h -- 




Ground Departure 
Operations 



Cruise Descent Terminal Final 

Area Approach 



I General Aviation D Commuter 

Airline 



I Major Airline 



Military 



Figure 5.8 - Winds Aloft Importance Ratings in Each Phase of Flight 
(Shown by Each Type of Flight Operation) 



One Traffic PLI element, Relative Sequencing, received significantly higher 
importance ratings from General Aviation pilots in Departure, Cruise, and Descent. 
These ratings are shown in Figure 5.9. These higher ratings may be due to the different 
airspace the General Aviation pilots often cruise in. Because they generally have lower 
cruise altitudes and shorter flight, many General Aviation flights stay in the lower level 
airspace, including the terminal areas of airports near their flight path. These types of 
airspace are often congested and pilots may often be asked to deviate from their assigned 
flight path or 'follow' another aircraft to maintain separation. 



63 



OX) 

a 

a 
DC 

« 



100% T 

90% -• 



u 



OX) 

a 

s 

o 

u 



fc -. 



70% ■■ 



•a 60% -- 



50% -■ 




Ground Departure 
Operations 



Cruise Descent Terminal Final 

Area Approach 



General Aviation □ Commuter 
Airline 



Major Airline 



Military 



Figure 5.9 -- Relative Sequencing Importance Ratings in Each Phase of Flight 
(Shown by Each Type of Flight Operation) 



The PLI element Next Communications Frequency was rated as more 
important by General Aviation pilots for all Phases of Flight except Final Approach, as 
shown in Figure 5.10. The Military pilots also gave this element very important ratings 
while the Commuter and Major Airline pilots both gave significantly lower ratings. The 
General Aviation pilots may perceive this element to be important because of the lower- 
altitude, more congested airspace they often cruise in, requiring more frequent frequency 
changes. In addition, General Aviation pilots often fly as single pilots and without the 
sophisticated autopilots of the airline aircraft. Therefore, because they are required to pay 
attention to both controlling the aircraft and communications, they may perceive PLI as 
an immediate and relevant source for this information element. 



64 



100% T 

&> 90% 



OS 






80% 
70% 



'O -■ 



U 50% 



© 40% -- 



f 30% 
| 20% 
£ 10% 




Ground Departure 
Operations 



Cruise Descent Terminal Final 

Area Approach 



General Aviation 



□ Commuter 
Airline 



Major Airline 



I Military 



Figure 5.10 -- Next Communication Frequency Importance Ratings in Each Phase of 

Flight 
(Shown by Type of Flight Operation) 



65 



5.6 Perceived PLI Importance by Military Pilots 

The overall ratings given by the Military pilots tended to be similar to those given 
by the Major Airline pilots, with some differences in the ratings given to specific PLI 
elements. Military pilots rated only two related PLI elements, Traffic - Controlled 
(Descent, & Terminal Area only) and Traffic Avoidance (Cruise), significantly higher 
than the other pilot types (p < 0.05). 

The importance ratings for these elements are shown in Figure 5.1 1. Because the 
different groups gave similiar percentages of Critical ratings, the percentages of 
Important ratings are shown instead. The Military pilots gave the highest ratings for all 
Phases of Flight except for Final Approach, where their ratings dropped to become the 
lowest. These differences may be a result of the Military pilots' different training and 
local Air Traffic Control at military facilities. 




Departure Descent 



Terminal 


Final 


Traffic 


Area 


Approach 


Avoidance 
Cruise 



I General Aviation □ Commuter 

Airline 



I Major Airline 



Military 



Figure 5.12 - Controlled Traffic & Traffic Avoidance 

Importance Ratings in Each POF 

(Shown by Each Type of Flight Operation) 

** Percentage of Importance Ratings Shown to Present Trend Throughout Flight 

66 



Chapter Six 

Pilot Information Requirements 
Subjective Responses 



The survey also asked pilots several questions about the information they would 
like to have presented in the cockpit. The first question asked for free responses to "What 
does the 'Big Picture' mean to you?", in an attempt to ascertain the information required 
for Global Situation Awareness. Two related free response questions solicited the total 
information content pilots would like datalink communications to provide. Finally, the 
mix of datalink and voice communications pilots would prefer was identified by the pilots 
on a numerical rating scale. This question was asked twice, for datalink systems both 
with and without compensation mechanisms for PLI loss. 

This chapter details the pilot responses to these questions. The general 
requirement for Traffic and Weather information was consistently indicated, as was the 
pilots preference for an mix of voice and datalink communications. 



67 



6.1 Information Required for Global Situation Awareness 

To solicit the information pilots perceive necessary for Global Situation 
Awareness, pilots were asked for a free response to this statement: There is a concern 
that, without "Party Line" information, pilots may lose a sense of the "Big Picture." What 
does the "Big Picture" mean to you?'. 

When the responses were examined, they were found to consistently describe the 
"Big Picture" in terms of items from several categories of information and activities. 
The frequency of responses in each category were tallied to quantify the percentage of 
pilots identifying each as necessary, as shown in Figure 6.1. Because each response 
could include items from several categories, these percentages combine to greater than 
unity. 



50% -r 




£ 10% 



Figure 6.1 - Information Required for Global Situation Awareness 

Nearly half of the responses indicated an understanding of Traffic information is 
required for Situation Awareness. The specific responses included a desire for 
knowledge of the positions of other aircraft, either relative to the pilot's aircraft or to 
ground landmarks. This information was listed as being useful for traffic avoidance and 
for tactical planning, such as a knowledge of sequencing and terminal routing. 



68 



Weather information was also included in many of the pilots' responses. The 
specific responses expressed a need for the overall weather situation and for specific 
weather information elements. Also, some responses included a knowledge of the impact 
these weather conditions on their operations caused by weather, such as the deviations to 
expect around thunderstorms. 

The next categories of responses are more ambiguous and were listed by fewer 
pilots. The ability to predict and plan ahead was mentioned by 16% of the pilots. Safety 
was mentioned by 6% of the pilots. Communication with ATC was mentioned by 6%. A 
sense of the best alternate courses of action was mentioned by 3%. A knowledge of the 
competence of the controllers and other pilots was listed by 4% of the pilots. 

The responses as a function of different types of flight operation are shown in 
Figure 6.2. Although their statistical significance can not be determined, several 
differences can be noted. The General Aviation and Military pilots included Traffic and 
Weather information and Communication more often than the Commuter and Major 
Airline pilots. The response frequency in all other categories were very similar. 



50% 





40% 


(/> 




C 




o 




ex 




06 


30% 


<+H 




o 






70% 


Si 




c 




<D 




O 




O-c 


10% 



0% 




Figure 6.2 -- Information Required for Global Situation Awareness 
As Given by Pilots of Different Flight Operations 



69 



6.2 Information Pilots Would Like Provided by Datalink 

To ascertain the information pilots feel is suitable for datalink communications, 
the surveyed asked for free responses to two questions: 

"Is there any particular information or images which you feel 
should be datalinked to aircraft? Do you have any suggestions for 
displaying this information in the cockpit?" 

"Can you suggest any methods of compensating for the loss of 
"Party Line" Information when using a digital datalink and some form of 
electronic display?" 

The responses were analyzed by tallying the categories of information and 
displays described by their answers. The final results are shown in Figure 6.3 for the 
most common categories of information. 







8 



U 



3 S 



'g 
s 

I 



! 



8 J? 



.u at 



Figure 6.3 -- Information Pilots Would Like Provided by Datalink Communications 



70 



Weather information was the most common category of information mentioned. 
This category includes several more specific responses, such as weather enroute, weather 
conditions at the destination, and specific weather information elements. The military 
pilots included this category in their responses the most often, which may result from 
their operations into airfields without the substantial weather reporting and forecasting 
capabilities of the major terminal areas. 

The ability to receive clearances via datalink communications was also mentioned 
by many pilots. The responses often cited specific examples, such as the current ability 
of major airline pilots to receive clearances at the gate through ACARS. This category 
was mentioned the most often by commuter airline pilots, who may be comparing their 
own aircraft systems to those of the larger airlines. This category was mentioned the least 
by General Aviation pilots, who may have not considered datalink clearance delivery a 
possibility. 

Around 15% of the pilots indicated a desire for information about nearby aircraft 
and collision avoidance. These suggestions included knowledge of relative position of 
other aircraft to the pilot's aircraft or to ground landmarks, a 'traffic display', and an 
indication of the aircraft's future path. No group of pilots made mention of this category 
of information noticeably more than any other. 

The next three categories identified specific types of clearances from Air Traffic 
Control that the pilots feel is suitable for datalink communications: Heading and Course 
Changes, Communication Frequencies, and Assigned Altitude. There was little disparity 
between the different types of flight operations in these responses. 

Finally, a small percentage of pilots indicated a desire for more advanced datalink 
displays showing a running dialogue of all transmissions — voice and datalink — on that 
frequency or showing the airport layout with taxi information. 

These responses provide valuable insight into the information pilots would like to 
receive with datalink communications. The questions themselves asked for completely 
free responses without providing any biases by giving examples of specific capabilities of 
datalink systems. However, most of the pilots providing responses can be assumed to be 
unfamiliar with the full technical potential of datalink systems and their possible displays, 
and therefore the responses may have been influenced by assumptions about limitations 
of the datalink system. 



71 



6.3 Pilot Preferred Mix of Voice and Datalink Communications 

Two questions asked pilots for numerical ratings of the mix of voice and datalink 
communications they would prefer, on a scale from '1' (Datalink Only) to '5' (VHF Voice 
Communication Only). The first question asked for a rating of datalink systems without 
compensation for PLI loss, while the second question asked for a rating of a compensated 
system. 

The pilots' average ratings are shown below in Figure 6.4. The ratings centered 
around the mid-point, indicating a preference for an even distribution of voice and 
datalink communications. The difference between ratings for the two questions is 
significant and shows an increased acceptance of datalink communications if care is taken 
to not reduce the information available to the pilot by reducing PLI without suitable 
compensation techniques. 



Military 



Major Airline 



Commuter Airline 



General Aviation 





□ Improved Datalink 
■ Datalink/Voice Mix 



Datalink 
Only 



Equal Mix 
Voice & Datalink 



Voice 
Only 



Figure 6.4 - Pilot Preferred Mix of Voice and Datalink Communications 



72 



Chapter Seven 
Survey Conclusions 



In order to solicit pilot opinions on the Importance, Availability and Accuracy of 
Party Line Information (PLI), a survey was distributed to pilots. Additional questions 
also asked for free responses about the information pilots would like presented by 
datalink communications and the information necessary for global situation awareness. 
The distribution was expanded from a previous study's to include pilots from four types 
of flight operations: General Aviation, Commuter Airlines, Major Airlines and Military. 
The survey responses can be summarized as: 

• For the information elements included in the survey, PLI is perceived as 
important overall by most pilots. This was demonstrated by the high mean importance 
rating. In addition, the majority of ratings received the highest Critical value. 

• Most of the specific information elements listed in the survey were identified as 
Critical or Important by a majority of the pilots. The most critical elements refer to 
immediate events required for tactical planning such as Aircraft on Landing Runway, 
Windshear, and Collision Avoidance. Other critical PLI elements refer to weather 
conditions useful for strategic planning of the flight path and final approach, such as 
Visibility & Ceiling and Thunderstorms. 

• The availability and accuracy of PLI was rated as generally reliable and 
accurate. However, these ratings did not receive the same proportion of extremely high 
values as the importance ratings. Therefore, no PLI elements were identified as highly 
"Reliable' or 'Common-Place'. 

• The importance ratings given most of the PLI elements correlated closely with 
their availability and accuracy ratings. However, several elements, including 
Uncontrolled Traffic and Error of Controller, received low availability and accuracy 
ratings but high importance ratings. These elements indicate information pilots feel is 
important but may not be well presented by Party Line communications. 

• The perceived importance of PLI was observed to vary between different Phases 
of Flight. Overall, PLI received higher importance ratings for the Phases of Flight closer 

73 



to the airport, such as Final Approach, and lower importance ratings during Cruise. The 
majority of the PLI elements followed this trend, although several PLI elements were 
identified as particularly important in specific phases. 

• A variation in PLI importance throughout the Phases of Flight were indicated by 
pilots of different types of flight operation. The General Aviation pilots tended to give 
consistent importance ratings throughout all Phases of Flight, while the Commuter and 
Major Airline pilots gave much lower ratings in Cruise than in Final Approach. 

• Some specific PLI elements were identified as particularly important to pilots 
from different types of flight operation. Commuter Airline pilots rated Uncontrolled 
Traffic very highly, and Major Airline pilots rated Ride Reports & Turbulence very 
highly. The General Aviation pilots gave high importance ratings to several weather PLI 
elements pertaining to conditions their aircraft are not well-equipped to handle, such as 
Icing Conditions. 

• In a free response question asking for the information pilots feel is required for 
Global Situation Awareness, pilots most often cited the a need for Traffic and Weather 
information. These responses mirrored their high importance ratings for Traffic and 
Weather PLI elements. This type of information was also cited often in free response 
questions about the information suitable for presentation by datalink communications. 

• The pilots' responses to the survey emphasized their need for specific Traffic 
and Weather information. Specific PLI elements were identified as very important by 
pilots. However, Party Line communications was not perceived to be very reliable or 
accurate, suggesting that it may not be the best modality for providing all types of 
information to pilots. 

• PLI was perceived to be the most important in the Terminal Area and Final 
Approach Phases of Flight, less important in Cruise. Unless the datalink system is well- 
compensated for PLI loss, this suggests initial implementation of datalink 
communications should not be in the high-density and high- workload Terminal Area 
control sectors. 

• Voice communications will remain the best modality for certain time critical 
information elements, such as Windshear and Missed Approach. 



74 



• Many other issues remain with the implementation of datalink communications 
systems. For example, new displays such as the traffic display provided by collision 
avoidance systems (TCAS) may enhance or replace PLI as a source of traffic information. 
This information is graphical and requires less dissemination by the pilot than a verbal or 
textual message. Further study of both the content and display of datalink systems should 
be made, with consideration to the instrumentation already available in the cockpit and 
the manner of presentation providing the most intuitive and compelling picture of the 
situation. 



75 



References 



1. Midkiff, A. H. & Hansman, R.J. Identification of Important "Party Line" Informational 

Elements and the Implications of Situational Awareness in the Datalink 
Environment, MIT Aeronautical Systems Laboratory Report ASL-92-2, May 1992 

2. Lee, A.T. & Lozito, S. Air-Ground Information Transfer in the National Airspace 

System, Proceedings of the Fifth Symposium on Aviation Psychology, April 17- 
20, 1989 

3. "ATA Urges Improving Air Traffic System Now" Aviation Week and Space Technology 

February 28, 1994 

4. Knox, C.E. & Scanlon, C.H. Flight Tests Using Data Link for Air Traffic Control and 

Weather Information Exchange, SAE Transactions, Journal of Aerospace, Sec.l, 
Vol 99-2, 1990 

5. Ryan, P. R. Airline Perspective on Data Link SAE Aerotech '92, October 5-8, 1992 

6. Armstrong, D. Certification of Airborne Data Link Equipment SAE Aerotech '92, 

October 5-8, 1992 

7. Lorge, F. ADS Engineering Trials Presentation to ATA Data Link Human Factors 

Group, February 23, 1993 

8. den Braven, W. Design and Evaluation of an Advanced Air-Ground Data-Link System 

for Air Traffic Control NASA Technical Memorandum 103899 January 1992 

9. Hogg, R. V. & Ledolter, J. Applied Statistics for Engineers and Physical Scientists 

Macmillan Publishing, New York 1987 

10. Siegel, A.F. Practical Business Statistics Irwin, Boston, 1990 

11. Hart, S.G., Hauser, J.R., & Lester, P.T. Inflight Evaluation of Four Measures of 

Pilot Workload Proceedings of the Human Facotrs Society 28th Annual Meeting, 
1984 



76 



Appendix A: 

Sample Copy of Party Line Information and 

Datalink Survey 



77 



DEPARTMENT OF 
AERONAUTICS AND ASTRONAUTICS 




CAMBRIDGE. MASSACHUSETTS 02139 
ROOM 37-458 (617) 253-7748 

TELEX 92-1473 FAX (617) 253-4196 



"Party Line" Information Survey 

Current plans for advanced Air Traffic Control systems anticipate using digital datalink in 
addition to voice transmissions for some ATC communications. These datalink communications 
will be addressed only to specific aircraft and may be displayed electronically to the pilot. There 
has been some concern over the possible loss of "Party Line" in the datalink environment, where 
"Party Line" is the information overheard in communications between other aircraft and ATC on 
shared voice frequencies. The use of datalink by any type of aircraft will affect everyone. Even if 
an aircraft is not equipped with datalink, other aircraft may communicate by datalink rather than 
voice and therefore not contribute any "Party Line" Information to the shared sector frequency. 

In an effort to obtain input from the perspective of the current users of the ATC system, the 
following survey has been developed to identify "Party Line" Information issues. The valuable 
input from active pilots, such as yourself, provides a real-world viewpoint on the current ATC 
system and will help to guide the implementation of datalink in a manner which will best combine 
the benefits of datalink and the current system. This study is funded by a grant from NASA and 
will be carried out by the Aeronautical Systems Lab at MIT. 

Thank you for your time. 

For further information, please feel free to contact: 



Principal Inv estigator : 

R. John Hansman, Jr., Ph.D. 
Boeing Associate Professor of 
Aeronautics & Astronautics 
MIT Rm. 33-115 
Cambridge MA 02139 
(617)253-2271 




h Assistant: 



Amy Pritchett 

Aeronautical Systems Laboratory 

MTTRm. 37-458 

Cambridge MA 02139 

(617) 253-7748 



CONFIDENTIALITY STATEMENT: Participation in this survey is completely voluntary. 
It is not necessary to give your name at any point. You may decline to answer any of the questions 
in this survey. All surveys will be de-identified and all information obtained from any individual 
survey will be kept confidential by the researchers at MIT. 



78 



BACKGROUND INFORMATION 

Please check the term that best describes the majority of your recent flight activity: 

General Aviation (Single-Engine) General Aviation (Multi) 

Corporate Commuter Airline Major Airline 

Military 

Check off your ratings: 

Private License Commercial License ATR 

IFR Multi-Engine CFI CFII 

Please estimate the following: 

Years flying Years as a professional pilot. 

Total time Total hours IFR. 

Flight hours in the last 12 months 

IFR hours in the last 12 months 

At this time, are you current to fly instruments? Yes No 

Please list the aircraft you most frequently fly: 



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4 
4 


5 
5 


ACARS 




2 


3 


4 


5 


Single Pilot IFR 
Other 




2 
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ADDITIONAL "PARTY LINE" & INFORMATION 
MANAGEMENT QUESTIONS 

There is a concern that, without "party line" information, pilots may lose a sense 
of the "Big Picture." What does the "Big Picture" mean to you? 



Considering the advantages of datalink (such as frequency congestion relief, 
unambiguous clearances, etc.) and of party line information (a 'sense of the big 
picture', ability to hear communications of all other aircraft in the sector), what 
mix of datalink and voice communications would you like to see? 



1 


2 


3 4 


5 


DATALINK 




EQUAL 


VHF VOICE 


ONLY 




DISTRIBUTION 


COMMUNICATION 






VOICE /DATALINK 


ONLY 



If some mechanism could be developed to datalink critical party line information 
to the aircraft (e.g. a status display with current wx, sequencing, and/or holding 
information), what mix of datalink and voice communications would you like? 



1 


2 3 4 


5 


ATALINK 


EQUAL 


VHF VOICE 


ONLY 


DISTRIBUTION 


COMMUNICATION 




VOICE /DATALINK 


ONLY 



Is there any particular information or images which you feel should be 
datalinked to aircraft? Do you have any suggestions for displaying this 
information in the cockpit? 



Can you suggest any methods of compensating for the loss of "Party Line" 
Information when using an digital datalink and some form of electronic display? 



Enter any comments about the significance of party line information that were 
not covered on the previous pages. 

85 



Have you ever been in a situation where lack of current weather information 
forced you to make a bad decision? 



Please rate the following in their importance to you for making weather 
deviation decisions: 

Least Most 

Important Important 

Airborne Weather RADAR 

ATC RADAR 

Personal Visual Observations 

Lightning Detection (e.g. Stormscope) 

PIREPs 

"Party Line" Information 

Terminal Forecast Weather Info. 

In-Flight Monitoring of ATIS 

Surface Observations from FSS 

In-Flight RADAR Described by FSS 

Predeparture RADAR Summary 

Other 



2 3 4 5 

2 3 4 5 

2 3 4 5 

2 3 4 5 

2 3 4 5 

2 3 4 5 

2 3 4 5 

2 3 4 5 

2 3 4 5 

2 3 4 5 

2 3 4 5 

2 3 4 5 



Please give any additional comments below. 



86 



Appendix B: 
Background Information Summary 



87 





Total 


GA 


Commuter 


Major Airline 


Military 


Distribution 


4375 


2000 


1075 


800 


500 


Responses 


658 


242 


124 


230 


124 


Response Rate 


15% 


12% 


12% 


29% 


25% 


Ratings & Licences 












Private 


22% 


57% 


0% 


0% 


4% 


Commercial 


32% 


42% 


16% 


8% 


61% 


ATR 


51% 


0% 


84% 


92% 


26% 


Multi-Engine 


84% 


41% 


100% 


100% 


100% 


CFI 


103% 


14% 


54% 


28% 


9% 


CFII 


26% 


9% 


51% 


20% 


4% 


IFR Current 


20% 


74% 


100% 


100% 


100% 


Flight Experience 












Years Flying 


18 


17 


18 


24 


10 


Years as Pro. Pilot 


15 


12 


12 


20 


9 


Total Flight Hours 


6478 


2172 


8194 


12177 


2936 


Flight Hours in Last Year 


438 


127 


729 


649 


380 


Region 












Northwest 


10% 


9% 


3% 


14% 


10% 


Southwest 


17% 


21% 


11% 


11% 


17% 


South Central 


7% 


5% 


10% 


4% 


10% 


North Central 


17% 


20% 


24% 


13% 


7% 


East Central 


8% 


8% 


3% 


5% 


14% 


Southeast 


15% 


14% 


20% 


9% 


18% 


Northeast 


17% 


17% 


11% 


22% 


9% 


Flight Distance 












Local 


4% 


8% 


0% 


0% 


6% 


Up to 100 nm 


10% 


20% 


5% 


2% 


4% 


100-500 nm 


52% 


61% 


87% 


28% 


25% 


500-1500 nm 


26% 


5% 


5% 


51% 


35% 


1500nm+ 


11% 


0% 


2% 


16% 


25% 


Frequency Congestion 












Very congested 


9% 


3% 


11% 


14% 


7% 


Busy 


41% 


32% 


49% 


38% 


38% 


Moderate 


44% 


52% 


25% 


29% 


50% 


Light 


2% 


4% 


0% 


1% 


0% 



88 



Appendix C: 

Importance, Availability and Accuracy Ratings of 

Party Line Information, 

Listed by PLI Element 



89 



Importance Ratings of PLI 





Statistics 


Percent 


of Responses 


at Each 


Value 




Averages 


Std. Dev. 


% of l's 


% of 2's 


% of 3's 


. %of4's 


%of5's 


Overall 


3.97 


1.18 


6% 


10% 


24% 


38% 


55% 


Ground Operations 


3.72 


1.31 


6% 


10% 


23% 


28% 


32% 


Next Comm. Frequency 


2.80 


1.30 


21% 


21% 


27% 


18% 


12% 


Wx - Overall 


3.75 


1.07 


4% 


7% 


25% 


35% 


28% 


TRW Buildup, Deviations 


4.20 


1.04 


3% 


4% 


14% 


26% 


52% 


Visibility & Ceiling 


3.79 


1.11 


5% 


7% 


22% 


34% 


31% 


Icing Conditions 


4.09 


1.11 


3% 


7% 


15% 


25% 


49% 


Ride Reports 


3.37 


1.13 


8% 


11% 


34% 


30% 


17% 


Winds Aloft 


2.67 


1.08 


17% 


25% 


37% 


15% 


5% 


Surface Winds 


3.61 


1.58 


5% 


10% 


30% 


35% 


20% 


Routing to Runway 


3.60 


1.15 


5% 


12% 


25% 


31% 


26% 


Sequencing 


3.66 


1.89 


3% 


10% 


32% 


35% 


20% 


Hold Shorf-other A/C 


3.96 


1.09 


3% 


8% 


20% 


28% 


40% 


A/C Crossing Rwy 


4.42 


0.89 


1% 


3% 


11% 


21% 


63% 


Error of Controller 


4.38 


0.83 


1% 


3% 


11% 


29% 


57% 


Departure 


3.84 


1.14 


5% 


9% 


23% 


32% 


39% 


Next Comm. Frequency 


3.42 


1.24 


8% 


15% 


26% 


26% 


24% 


Wx - Overall 


3.88 


0.96 


3% 


4% 


24% 


40% 


28% 


TRW Buildup, Deviations 


4.45 


0.75 


0% 


2% 


8% 


32% 


58% 


Visibility & Ceiling 


3.41 


1.18 


8% 


14% 


27% 


31% 


20% 


Icing Conditions 


4.26 


0.91 


1% 


3% 


13% 


32% 


50% 


Ride Reports 


3.73 


0.94 


2% 


8% 


29% 


40% 


22% 


Winds Aloft 


2.89 


1.08 


11% 


22% 


41% 


16% 


9% 


Surface Winds 


3.00 


1.37 


20% 


17% 


26% 


20% 


18% 


Traffic-Controlled 


4.48 


0.75 


0% 


2% 


8% 


30% 


60% 


Traffic-Uncontrolled 


4.61 


0.71 


0% 


2% 


5% 


21% 


71% 


Sequencing 


3.78 


0.98 


3% 


6% 


29% 


38% 


25% 


Error of Controller 


4.23 


0.91 


1% 


4% 


17% 


29% 


49% 


Cruise 


3.69 


1.20 


7% 


10% 


22% 


30% 


31% 


Next Comm. Frequency 


3.34 


1.22 


10% 


14% 


29% 


28% 


20% 


Wx - Overall 


3.87 


0.95 


2% 


5% 


26% 


38% 


29% 


TRW Buildup, Deviations 


4.44 


0.73 


0% 


1% 


9% 


33% 


56% 


Visibility & Ceiling 


3.15 


1.32 


14% 


19% 


26% 


22% 


20% 


Icing Conditions 


4.19 


0.96 


2% 


4% 


14% 


33% 


47% 


Ride Reports 


3.89 


0.89 


1% 


4% 


25% 


43% 


26% 


Winds Aloft 


3.22 


1.07 


6% 


17% 


38% 


26% 


13% 


Surface Winds 


2.54 


1.36 


30% 


23% 


20% 


14% 


12% 


Traffic Avoidance 


4.35 


0.93 


2% 


3% 


10% 


28% 


57% 


Sequencing 


3.52 


1.13 


6% 


12% 


28% 


32% 


22% 


Error of Controller | 


4.01 


1.02 


2% 


5% 


23% 


28% 


41% 



90 



Importance Ratings of PLI (con't) 



Statistics 

Averages Std. Dev, 



Percent of Responses at Each Value 

%ofl's %of2's %of3's %of4's %of5's 



Descent 

Next Comm. Frequency 

Wx - Overall 

TRW Buildup, Deviations 

Visibility & Ceiling 

Icing Conditions 

Ride Reports 

Winds Aloft 

Surface Winds 

Traffic-Controlled 

Traffic-Uncontrolled 

Sequencing 

Hold Situation 

Error of Controller 

Terminal Area 

Next Comm. Frequency 

Wx - Overall 

TRW Buildup, Deviations 

Visiblilty & Ceiling 

Icing Conditions 

Ride Reports 

Winds Aloft 

Surface Winds 

Traffic-Controlled 

Traffic-Uncontrolled 

Sequencing 

Hold Situation 

Terminal Routing 

Approach Clearance 

Error of Controller 



4.01 


1.06 


3% 


6% 


18% 


32% 


41% 


3.64 


1.21 


7% 


11% 


23% 


29% 


30% 


4.01 


0.91 


2% 


3% 


21% 


41% 


33% 


4.53 


0.66 


0% 


1% 


6% 


32% 


61% 


4.12 


0.98 


2% 


4% 


17% 


33% 


43% 


4.28 


0.87 


1% 


3% 


14% 


32% 


50% 


3.70 


0.95 


1% 


9% 


30% 


38% 


22% 


2.64 


1.15 


17% 


33% 


29% 


13% 


8% 


3.79 


1.11 


5% 


8% 


20% 


37% 


30% 


4.47 


0.83 


1% 


2% 


8% 


26% 


63% 


4.51 


0.84 


1% 


3% 


7% 


21% 


68% 


3.96 


0.88 


1% 


5% 


20% 


45% 


29% 


4.28 


0.77 


0% 


1% 


14% 


39% 


45% 


4.19 


0.92 


1% 


4% 


18% 


30% 


47% 


4.16 


1.12 


4% 


6% 


15% 


34% 


56% 


3.86 


1.18 


6% 


8% 


18% 


30% 


38% 


4.08 


0.98 


3% 


4% 


15% 


37% 


40% 


4.52 


0.76 


1% 


2% 


6% 


26% 


64% 


4.44 


0.80 


1% 


2% 


9% 


29% 


59% 


4.29 


0.91 


1% 


3% 


12% 


30% 


53% 


3.65 


1.09 


4% 


11% 


28% 


31% 


26% 


2.52 


1.27 


27% 


27% 


24% 


13% 


10% 


4.27 


1.82 


2% 


4% 


13% 


36% 


46% 


4.62 


0.69 


0% 


2% 


6% 


21% 


71% 


4.62 


0.73 


1% 


2% 


6% 


18% 


73% 


4.16 


0.82 


1% 


2% 


14% 


44% 


38% 


4.19 


0.86 


1% 


3% 


15% 


38% 


43% 


4.35 


0.81 


1% 


2% 


11% 


35% 


52% 


4.47 


0.82 


1% 


2% 


8% 


26% 


62% 


4.33 


0.89 


1% 


2% 


14% 


26% 


56% 



91 



Importance Ratings of PLI (con't) 





Statistics 


Percent 


of Responses 


at Each 


Value 




Averages 


Std. Dev. 


% of l's 


%of2's 


% of 3's 


, %of4's 


% of 5's 


Final Approach 


4.17 


1.22 


5% 


6% 


14% 


27% 


60% 


Next Comm. Frequency 


3.59 


1.36 


12% 


11% 


20% 


22% 


35% 


Wx - Overall 


3.87 


1.20 


6% 


8% 


19% 


27% 


40% 


TRW Buildup, Deviations 


4.25 


1.07 


4% 


5% 


12% 


22% 


57% 


Visibility & Ceiling 


4.62 


2.16 


1% 


2% 


7% 


22% 


68% 


Icing Conditions 


4.09 


1.10 


3% 


8% 


14% 


26% 


48% 


Ride Reports 


3.52 


1.30 


8% 


17% 


18% 


27% 


29% 


Winds Aloft 


2.40 


1.36 


36% 


23% 


18% 


12% 


11% 


Windshear 


4.76 


0.57 


0% 


0% 


3% 


15% 


81% 


Surface Winds 


4.48 


0.77 


0% 


2% 


8% 


27% 


62% 


Traffic-Controlled 


4.58 


0.77 


1% 


2% 


7% 


18% 


72% 


Traffic-Uncontrolled 


4.61 


0.79 


1% 


2% 


7% 


15% 


75% 


Missed Approach - Wx 


4.63 


0.64 


0% 


1% 


4% 


24% 


70% 


Missed Approach - Other 


4.27 


0.88 


1% 


4% 


13% 


33% 


50% 


A/C on Runway 


4.83 


0.47 


0% 


0% 


2% 


12% 


86% 


Braking Action 


4.42 


0.77 


0% 


2% 


8% 


32% 


56% 


Taxiway Turnoff 


3.67 


1.04 


4% 


7% 


31% 


33% 


24% 


Sequencing 


4.06 


0.91 


2% 


4% 


17% 


42% 


36% 


Error of Controller 


4.41 


0.88 


1% 


3% 


12% 


24% 


61% 


Prosodic & 
















General Elements 
















Sector Congestion 


3.93 


1.14 


1% 


5% 


20% 


52% 


22% 


Controller Exp. 


3.85 


0.92 


1% 


7% 


24% 


43% 


26% 


Other Pilot's Exp. 


3.57 


1.01 


4% 


9% 


32% 


36% 


19% 


Controller's Urgency 


4.32 


0.77 


0% 


2% 


10% 


40% 


48% 


Other Pilot's Urgency 


4.00 


0.92 


1% 


5% 


22% 


37% 


35% 


B/G Reassurance 


3.61 


1.06 


5% 


9% 


28% 


38% 


21% 


Call Sign Confusion 


4.53 


0.73 


0% 


2% 


7% 


27% 


64% 


Lost Communication 


4.38 


0.77 


0% 


2% 


11% 


34% 


53% 


Navaid Problems 


4.17 


0.90 


1% 


3% 


17% 


35% 


44% 



92 



Availability Ratings of PLI 



Statistics Percent of Responses at Each Value 

:raees Std. Dev. %ofl's %of2's %of3's %of4's % of5's 



Overall 

Ground Operations 

Next Comm. Frequency 

Wx - Overall 

TRW Buildup, Deviations 

Visibility & Ceiling 

Icing Conditions 

Ride Reports 

Winds Aloft 

Surface Winds 

Routing to Runway 

Sequencing 

Hold Short"-other A/C 

A/C Crossing Rwy 

Error of Controller 

Departure 

Next Comm. Frequency 

Wx - Overall 

TRW Buildup, Deviations 

Visibility & Ceiling 

Icing Conditions 

Ride Reports 

Winds Aloft 

Surface Winds 

Traffic-Controlled 

Traffic-Uncontrolled 

Sequencing 

Error of Controller 

Cruise 

Next Comm. Frequency 

Wx - Overall 

TRW Buildup, Deviations 

Visibility & Ceiling 

Icing Conditions 

Ride Reports 

Winds Aloft 

Surface Winds 

Traffic Avoidance 

Sequencing 

Error of Controller 



3.64 


1.09 


3% 


11% 


26% 


35% 


24% 


3.61 


1.13 


4% 


13% 


27% 


31% 


26% 


3.96 


1.07 


2% 


8% 


22% 


28% 


41% 


3.59 


1.03 


2% 


12% 


31% 


32% 


22% 


3.50 


1.06 


3% 


15% 


29% 


34% 


19% 


3.93 


1.01 


2% 


8% 


21% 


34% 


35% 


3.41 


1.06 


4% 


16% 


33% 


29% 


17% 


3.16 


1.18 


9% 


21% 


29% 


26% 


14% 


2.81 


1.26 


18% 


24% 


28% 


18% 


12% 


4.00 


1.03 


2% 


7% 


19% 


32% 


40% 


3.84 


1.00 


3% 


6% 


25% 


38% 


29% 


3.63 


1.03 


2% 


12% 


29% 


35% 


22% 


3.90 


0.97 


2% 


6% 


26% 


35% 


31% 


4.05 


0.96 


2% 


5% 


20% 


34% 


39% 


3.07 


1.13 


7% 


25% 


33% 


22% 


13% 


3.50 


1.09 


4% 


14% 


30% 


32% 


20% 


3.95 


1.01 


1% 


8% 


21% 


32% 


37% 


3.45 


0.99 


3% 


12% 


37% 


33% 


15% 


3.75 


0.88 


1% 


7% 


29% 


43% 


20% 


3.43 


1.08 


4% 


15% 


33% 


30% 


19% 


3.57 


0.95 


1% 


11% 


35% 


35% 


18% 


3.60 


0.94 


1% 


12% 


31% 


39% 


17% 


2.89 


1.11 


10% 


28% 


33% 


19% 


9% 


3.31 


1.33 


13% 


14% 


26% 


23% 


24% 


4.12 


0.84 


1% 


3% 


17% 


43% 


37% 


3.23 


1.18 


8% 


20% 


29% 


26% 


17% 


3.59 


0.95 


2% 


10% 


32% 


38% 


17% 


3.09 


1.05 


4% 


26% 


36% 


21% 


12% 


3.47 


1.07 


4% 


14% 


30% 


33% 


18% 


3.86 


1.00 


2% 


8% 


23% 


36% 


31% 


3.51 


0.94 


1% 


12% 


37% 


34% 


16% 


3.83 


0.84 


0% 


6% 


26% 


46% 


22% 


3.24 


1.15 


8% 


19% 


31% 


27% 


15% 


3.58 


0.93 


1% 


11% 


33% 


37% 


17% 


3.72 


0.91 


1% 


9% 


28% 


42% 


20% 


3.09 


1.03 


5% 


26% 


35% 


24% 


10% 


2.91 


1.33 


19% 


21% 


24% 


21% 


14% 


3.87 


0.89 


1% 


5% 


25% 


43% 


26% 


3.44 


1.01 


3% 


15% 


32% 


35% 


15% 


3.04 


1.07 


6% 


26% 


36% 


21% 


11% 



93 



Availability Ratings of PLI (con't) 





Statistics 


Percent 


of Responses 


at Each 


Value 




Averages 


Std. Dev. 


% of l's 


%of2's 


% of 3's 


» %of4's 


%of5's 


Descent 


3.64 


1.16 


3% 


10% 


28% 


37% 


21% 


Next Comm. Frequency 


3.97 


0.96 


1% 


6% 


21% 


37% 


34% 


Wx - Overall 


3.78 


1.88 


1% 


7% 


29% 


44% 


18% 


TRW Buildup, Deviations 


3.86 


0.82 


1% 


4% 


25% 


49% 


21% 


Visiblilty & Ceiling 


3.83 


0.94 


1% 


6% 


26% 


39% 


27% 


Icing Conditions 


3.67 


0.87 


1% 


7% 


32% 


43% 


16% 


Ride Reports 


3.57 


0.90 


1% 


10% 


37% 


36% 


16% 


Winds Aloft 


2.92 


1.62 


11% 


27% 


33% 


20% 


8% 


Surface Winds 


3.69 


1.08 


4% 


10% 


23% 


36% 


25% 


Traffic-Controlled 


4.05 


0.86 


1% 


3% 


20% 


43% 


33% 


Traffic-Uncontrolled 


3.21 


1.17 


9% 


20% 


28% 


29% 


15% 


Sequencing 


3.69 


0.90 


1% 


7% 


32% 


40% 


19% 


Hold Situation 


3.84 


0.87 


0% 


7% 


26% 


43% 


23% 


Error of Controller 


3.10 


1.03 


5% 


25% 


36% 


25% 


9% 


Terminal Area 


3.82 


1.01 


3% 


8% 


22% 


39% 


28% 


Next Comm. Frequency 


4.14 


0.86 


1% 


4% 


16% 


40% 


39% 


Wx - Overall 


3.82 


0.91 


2% 


5% 


25% 


44% 


24% 


TRW Buildup, Deviations 


3.93 


0.81 


0% 


4% 


23% 


48% 


24% 


Visiblilty & Ceiling 


4.15 


0.83 


Wo 


3% 


17% 


41% 


39% 


Icing Conditions 


3.73 


0.91 


1% 


8% 


29% 


41% 


21% 


Ride Reports 


3.53 


0.99 


2% 


14% 


31% 


36% 


17% 


Winds Aloft 


2.69 


1.22 


18% 


30% 


26% 


17% 


9% 


Surface Winds 


4.08 


0.92 


1% 


4% 


17% 


38% 


38% 


Traffic-Controlled 


4.27 


0.74 


0% 


1% 


12% 


44% 


42% 


Traffic-Uncontrolled 


3.34 


1.17 


7% 


18% 


27% 


29% 


18% 


Sequencing 


3.89 


0.86 


1% 


4% 


25% 


44% 


25% 


Hold Situation 


3.89 


0.88 


1% 


5% 


24% 


44% 


26% 


Terminal Routing 


4.17 


0.77 


0% 


2% 


15% 


45% 


37% 


Approach Clearance 


4.34 


0.74 


0% 


1% 


11% 


40% 


48% 


Error of Controller 


3.25 


1.07 


5% 


21% 


33% 


28% 


13% 



94 



Availability Ratings of PLI (con't) 



Final Approach 

Next Comm. Frequency 

Wx - Overall 

TRW Buildup, Deviations 

Visibility & Ceiling 

Icing Conditions 

Ride Reports 

Winds Aloft 

Windshear 

Surface Winds 

Traffic-Controlled 

Traffic-Uncontrolled 

Missed Approach - Wx 

Missed Approach - Other 

A/C on Runway 

Braking Action 

Taxiway Turnoff 

Sequencing 

Error of Controller 



Statistics 


Percent 


of Responses 


at Each 


Value 


Averages 


Std. Dev. 


% of l's 


%of2's 


% of 3's 


, %of4's 


% of 5's 


3.75 


1.07 


3% 


10% 


24% 


35% 


28% 


4.15 


0.94 


1% 


5% 


16% 


33% 


45% 


3.71 


1.05 


4% 


9% 


24% 


39% 


24% 


3.76 


0.96 


2% 


9% 


25% 


41% 


23% 


4.26 


0.81 


0% 


2% 


13% 


39% 


45% 


3.63 


1.00 


2% 


12% 


28% 


38% 


20% 


3.44 


1.07 


4% 


16% 


31% 


32% 


18% 


2.58 


1.27 


24% 


28% 


23% 


14% 


10% 


3.90 


0.90 


1% 


5% 


25% 


39% 


29% 


4.30 


0.81 


0% 


3% 


13% 


35% 


49% 


4.28 


0.78 


0% 


2% 


12% 


40% 


45% 


3.29 


1.19 


7% 


19% 


29% 


25% 


19% 


3.99 


0.93 


1% 


6% 


20% 


39% 


34% 


3.84 


0.99 


1% 


9% 


24% 


37% 


29% 


3.90 


0.96 


1% 


9% 


18% 


42% 


30% 


3.78 


0.96 


1% 


8% 


28% 


38% 


26% 


3.47 


1.02 


3% 


15% 


33% 


32% 


17% 


3.83 


0.87 


1% 


4% 


28% 


43% 


23% 


3.15 


1.09 


6% 


23% 


34% 


25% 


12% 



Prosodic & General 

Sector Congestion 
Controller Exp. 
Other Pilot's Exp. 
Controller's Urgency 
Other Pilot's Urgency 
B/G Reassurance 
Call Sign Confusion 
Lost Communication 
Navaid Problems 



Elements 

3.86 
3.61 
3.57 
3.97 
3.73 
3.85 
3.60 
3.07 
3.17 



0.87 
0.94 
0.97 
1.19 
0.94 
0.97 
1.00 
1.09 
1.03 



0% 
1% 
2% 
1% 
1% 
1% 
1% 
7% 



5% 

11% 

9% 

5% 

7% 

8% 

16% 

26% 

24% 



30% 
33% 
35% 
24% 
33% 
26% 
28% 
31% 
35% 



39% 
37% 
35% 
40% 

35% 
35% 
35% 
27% 
27% 



26% 



18% 
30% 
24% 
30% 
21% 
10% 
11% 



95 



Accuracy Ratings of PLI 





Statistics 


Percent 


of Responses 


at Each 


Value 




Averages 


Std. Dev. 


% of l's 


%of2's 


% of 3's 


%of4's 


%of5's 


Overall 


3.81 


0.96 


2% 


6% 


25% 


41% 


25% 


Ground Operations 


3.79 


1.03 


3% 


7% 


24% 


37% 


28% 


Next Comm. Frequency 


3.84 


1.06 


4% 


7% 


22% 


36% 


31% 


Wx - Overall 


3.76 


0.91 


1% 


6% 


28% 


43% 


21% 


TRW Buildup, Deviations 


3.84 


0.98 


2% 


6% 


24% 


40% 


27% 


Visibility & Ceiling 


3.94 


0.94 


1% 


5% 


22% 


39% 


32% 


Icing Conditions 


3.71 


1.01 


3% 


10% 


25% 


39% 


23% 


Ride Reports 


3.66 


1.04 


3% 


10% 


27% 


36% 


23% 


Winds Aloft 


3.29 


1.14 


7% 


16% 


32% 


28% 


16% 


Surface Winds 


3.86 


1.01 


2% 


7% 


22% 


38% 


30% 


Routing to Runway 


3.76 


1.08 


4% 


8% 


23% 


36% 


28% 


Sequencing 


3.80 


1.01 


3% 


7% 


24% 


38% 


27% 


Hold Shorf-other A/C 


4.03 


0.92 


2% 


3% 


20% 


39% 


35% 


A/C Crossing Rwy 


4.14 


0.93 


2% 


2% 


17% 


36% 


43% 


Error of Controller 


3.64 


1.05 


4% 


8% 


32% 


33% 


23% 


Departure 


3.74 


0.96 


2% 


7% 


26% 


42% 


22% 


Next Comm. Frequency 


3.97 


0.97 


2% 


6% 


19% 


39% 


34% 


Wx - Overall 


3.77 


0.83 


1% 


4% 


31% 


45% 


19% 


TRW Buildup, Deviations 


3.94 


0.79 


0% 


3% 


23% 


49% 


24% 


Visibility & Ceiling 


3.81 


0.90 


2% 


5% 


26% 


44% 


23% 


Icing Conditions 


3.77 


0.89 


1% 


7% 


26% 


45% 


20% 


Ride Reports 


3.79 


0.85 


1% 


5% 


29% 


44% 


21% 


Winds Aloft 


3.37 


1.03 


4% 


16% 


34% 


33% 


14% 


Surface Winds 


3.65 


1.08 


5% 


9% 


26% 


37% 


24% 


Traffic-Controlled 


4.11 


0.80 


1% 


3% 


14% 


50% 


33% 


Traffic-Uncontrolled 


3.32 


1.15 


8% 


15% 


27% 


34% 


15% 


Sequencing 


3.76 


0.90 


1% 


7% 


26% 


44% 


21% 


Error of Controller 


3.57 


0.98 


3% 


8% 


36% 


34% 


18% 


Cruise 


3.71 


0.95 


2% 


7% 


28% 


42% 


21% 


Next Comm. Frequency 


3.91 


0.99 


2% 


6% 


20% 


40% 


31% 


Wx - Overall 


3.74 


0.83 


1% 


5% 


31% 


46% 


17% 


TRW Buildup, Deviations 


3.94 


0.80 


0% 


4% 


21% 


50% 


24% 


Visibility & Ceiling 


3.63 


0.95 


3% 


7% 


32% 


40% 


18% 


Icing Conditions 


3.72 


0.89 


1% 


6% 


30% 


43% 


19% 


Ride Reports 


3.85 


0.85 


0% 


6% 


25% 


46% 


23% 


Winds Aloft 


3.50 


0.99 


3% 


12% 


32% 


38% 


15% 


Surface Winds 


3.37 


1.15 


8% 


13% 


28% 


34% 


16% 


Traffic Avoidance 


3.91 


0.89 


2% 


5% 


21% 


48% 


25% 


Sequencing 


3.72 


0.94 


2% 


8% 


27% 


43% 


20% 


Error of Controller | 


3.52 


0.98 


3% 


9% 


37% 


34% 


17% 



96 



Accuracy Ratings of PLI (con't) 



Descent 

Next Comm. Frequency 

Wx - Overall 

TRW Buildup, Deviations 

Visibility & Ceiling 

Icing Conditions 

Ride Reports 

Winds Aloft 

Surface Winds 

Traffic-Controlled 

Traffic-Uncontrolled 

Sequencing 

Hold Situation 

Error of Controller 

Terminal Area 

Next Comm. Frequency 

Wx - Overall 

TRW Buildup, Deviations 

Visibility & Ceiling 

Icing Conditions 

Ride Reports 

Winds Aloft 

Surface Winds 

Traffic-Controlled 

Traffic-Uncontrolled 

Sequencing 

Hold Situation 

Terminal Routing 

Approach Clearance 

Error of Controller 



Statistics 


Percent 


of Responses at Each 


Value 


Averages 


Std. Dev. 


%of l's 


% of 2's 


% of 3's 


%of4's 


%of5's 


3.79 


0.91 


2% 


6% 


25% 


45% 


22% 


3.99 


0.93 


1% 


6% 


17% 


42% 


32% 


3.86 


0.77 


0% 


3% 


26% 


51% 


19% 


3.95 


0.75 


0% 


2% 


23% 


51% 


23% 


3.97 


0.82 


1% 


3% 


21% 


49% 


26% 


3.81 


0.85 


1% 


5% 


26% 


48% 


20% 


3.76 


0.82 


0% 


5% 


31% 


45% 


18% 


3.32 


1.02 


4% 


17% 


33% 


34% 


11% 


3.85 


0.90 


2% 


6% 


21% 


47% 


24% 


4.07 


0.78 


1% 


2% 


14% 


54% 


29% 


3.36 


1.14 


7% 


17% 


26% 


34% 


16% 


3.84 


0.84 


1% 


4% 


25% 


48% 


21% 


3.84 


0.90 


1% 


6% 


22% 


46% 


23% 


3.53 


0.96 


3% 


9% 


37% 


35% 


16% 


3.91 


0.92 


2% 


5% 


21% 


44% 


28% 


4.17 


0.85 


1% 


3% 


15% 


41% 


41% 


3.93 


0.82 


1% 


3% 


23% 


49% 


24% 


4.00 


0.76 


0% 


2% 


22% 


49% 


26% 


4.12 


0.78 


1% 


2% 


14% 


50% 


33% 


3.84 


0.85 


1% 


4% 


27% 


46% 


22% 


3.74 


0.87 


1% 


6% 


32% 


42% 


20% 


3.21 


1.16 


10% 


16% 


32% 


29% 


14% 


4.06 


0.81 


1% 


3% 


17% 


49% 


31% 


4.19 


0.76 


1% 


2% 


11% 


49% 


36% 


3.42 


1.16 


6% 


17% 


25% 


33% 


19% 


3.96 


0.80 


0% 


3% 


21% 


50% 


25% 


3.92 


0.89 


1% 


5% 


22% 


44% 


27% 


4.13 


0.80 


0% 


3% 


15% 


46% 


35% 


4.24 


0.82 


1% 


2% 


12% 


41% 


43% 


3.64 


0.98 


3% 


8% 


31% 


38% 


20% 



97 



Accuracy Ratings of PLI (con't) 





Statistics 


Percent 


of Responses 


at Each 


Value 




Averages 


Std. Dev. 


% of l's 


%of2's 


% of 3's 


i %of4's 


%of5's 


Final Approach 


3.91 


0.96 


2% 


5% 


22% 


40% 


30% 


Next Comm. Frequency 


4.25 


0.86 


1% 


3% 


14% 


35% 


47% 


Wx - Overall 


3.91 


0.85 


1% 


4% 


23% 


47% 


25% 


TRW Buildup, Deviations 


3.99 


0.82 


1% 


3% 


21% 


48% 


28% 


Visibility & Ceiling 


4.19 


0.80 


0% 


2% 


15% 


43% 


39% 


Icing Conditions 


3.82 


0.89 


1% 


5% 


28% 


42% 


24% 


Ride Reports 


3.69 


0.95 


2% 


7% 


30% 


39% 


21% 


Winds Aloft 


3.14 


1.20 


12% 


16% 


34% 


24% 


14% 


Windshear 


3.88 


0.94 


1% 


7% 


21% 


42% 


28% 


Surface Winds 


4.18 


0.82 


1% 


3% 


13% 


43% 


39% 


Traffic-Controlled 


4.25 


0.78 


1% 


2% 


12% 


43% 


42% 


Traffic-Uncontrolled 


3.43 


1.19 


8% 


15% 


24% 


33% 


20% 


Missed Approach - Wx 


4.19 


0.84 


1% 


2% 


14% 


41% 


41% 


Missed Approach - Other 


4.05 


0.89 


1% 


3% 


20% 


39% 


36% 


A/C on Runway 


4.16 


0.86 


1% 


3% 


16% 


40% 


40% 


Braking Action 


3.85 


0.90 


1% 


6% 


25% 


44% 


24% 


Taxiway Turnoff 


3.72 


0.96 


2% 


6% 


32% 


37% 


22% 


Sequencing 


3.92 


0.88 


2% 


3% 


24% 


44% 


27% 


Error of Controller 


3.61 


1.01 


4% 


8% 


34% 


35% 


20% 


Prosodic & General E 


llements 














Sector Congestion 


3.96 


0.97 


2% 


5% 


23% 


36% 


34% 


Controller Exp. 


3.95 


0.88 


1% 


3% 


24% 


43% 


29% 


Other Pilot's Exp. 


3.87 


0.85 


0% 


5% 


27% 


43% 


25% 


Controller's Urgency 


3.75 


0.94 


1% 


6% 


32% 


36% 


24% 


Other Pilot's Urgency 


3.71 


0.93 


2% 


8% 


30% 


40% 


21% 


B/G Reassurance 


3.70 


0.95 


2% 


7% 


34% 


35% 


23% 


Call Sign Confusion 


3.63 


0.95 


2% 


8% 


34% 


36% 


19% 


Lost Communication 


3.53 


0.99 


3% 


10% 


34% 


36% 


16% 


Navaid Problems 


3.45 


0.99 


4% 


11% 


36% 


34% 


14% 



98 



Appendix D: 
Importance Ratings of Party Line Information, 

Listed by Phase of Flight 



99 



Importance Ratings by Phase of Flight 





Statistics 


Percentage of 


Responses 


> at Each Valu 


Combined Ratings 


Averages Std. Dev. 


% l's 


% 2's 


% 3's 


% 4's 


% 5's 


Ground Operations 


3.72 


1.31 


6% 


10% 


23% 


28% 


32% 


Departure 


3.84 


1.14 


5% 


9% 


23% 


32% 


39% 


Cruise 


3.69 


1.20 


21% 


29% 


67% 


89% 


93% 


Descent 


4.01 


1.06 


9% 


19% 


51% 


94% 


118% 


Terminal Area 


4.16 


1.12 


4% 


6% 


15% 


34% 


56% 


Final Approach 


4.17 


1.22 


5% 


6% 


14% 


27% 


60% 


Controlled Traffic 


Averages 


Std. Dev. 


%1's 


%2's 


%3's 


%4's 


%5's 


Ground Operations 
















Departure 


4.48 


0.75 


0% 


2% 


8% 


30% 


60% 


Cruise 
















Descent 


4.47 


0.83 


1% 


2% 


8% 


26% 


63% 


Terminal Area 


4.62 


0.69 


0% 


2% 


6% 


21% 


71% 


Final Approach 


4.58 


0.77 


1% 


2% 


7% 


18% 


72% 


Uncontrolled Traffic 


Averages 


Std. Dev. 


%1's 


%2's 


%3's 


%4's 


%5's 


Ground Operations 
















Departure 


4.61 


0.71 


0% 


2% 


5% 


21% 


71% 


Cruise 
















Descent 


4.51 


0.84 


1% 


3% 


7% 


21% 


68% 


Terminal Area 


4.62 


0.73 


1% 


2% 


6% 


18% 


73% 


Final Approach 


4.61 


0.79 


1% 


2% 


7% 


15% 


75% 


Traffic Avoidance 


Averages 


Std. Dev. 


%1's 


%2's 


%3's 


%4's 


%5's 


Cruise 


4.35 


0.93 


2% 


3% 


10% 


28% 


57% 


Relative Sequencing 


Averages 


Std. Dev. 


%1's 


%2's 


%3's 


%4's 


%5's 


Ground Operations 


3.66 


1.89 


3% 


10% 


32% 


35% 


20% 


Departure 


3.78 


0.98 


3% 


6% 


29% 


38% 


25% 


Cruise 


3.52 


1.13 


6% 


12% 


28% 


32% 


22% 


Descent 


3.96 


0.88 


1% 


5% 


20% 


45% 


29% 


Terminal Area 


4.16 


0.82 


1% 


2% 


14% 


44% 


38% 


Final Approach 


4.06 


0.91 


2% 


4% 


17% 


42% 


36% 


Weather Overall 


Averages 


Std. Dev. 


% l's 


%2's 


%3's 


%4's 


% 5's 


Ground Operations 


3.75 


1.07 


4% 


7% 


25% 


35% 


28% 


Departure 


3.88 


0.96 


3% 


4% 


24% 


40% 


28% 


Cruise 


3.87 


0.95 


2% 


5% 


26% 


38% 


29% 


Descent 


4.01 


0.91 


2% 


3% 


21% 


41% 


33% 


Terminal Area 


4.08 


0.98 


3% 


4% 


15% 


37% 


40% 


Final Approach 


3.87 


1.20 


6% 


8% 


19% 


27% 


40% 



100 



Importance Ratings by Phase of Flight (con't) 





Statistics 


Percentage of F 


Responses 


at Eac 


h Valu 


TRW Buildups 


Averages 


Std. Dev. 


% l's 


%2's 


%3's 


%4's 


%5's 


Ground Operations 


4.20 


1.04 


3% 


4% 


14% 


26% 


52% 


Departure 


4.45 


0.75 


0% 


2% 


8% 


32% 


58% 


Cruise 


4.44 


0.73 


0% 


1% 


9% 


33% 


56% 


Descent 


4.53 


0.66 


0% 


1% 


6% 


32% 


61% 


Terminal Area 


4.52 


0.76 


1% 


2% 


6% 


26% 


64% 


Final Approach 


4.25 


1.07 


4% 


5% 


12% 


22% 


57% 


Visibility & Ceiling 


Averages 


Std. Dev. 


% l's 


%2's 


%3's 


%4's 


%5's 


Ground Operations 


3.79 


1.11 


5% 


7% 


22% 


34% 


31% 


Departure 


3.41 


1.18 


8% 


14% 


27% 


31% 


20% 


Cruise 


3.15 


1.32 


14% 


19% 


26% 


22% 


20% 


Descent 


4.12 


0.98 


2% 


4% 


17% 


33% 


43% 


Terminal Area 


4.44 


0.80 


1% 


2% 


9% 


29% 


59% 


Final Approach 


4.62 


2.16 


1% 


2% 


7% 


22% 


68% 


Icing Conditions 


Averages 


Std. Dev. 


%1's 


%2's 


%3's 


%4's 


%5's 


Ground Operations 


4.09 


1.11 


3% 


7% 


15% 


25% 


49% 


Departure 


4.26 


0.91 


1% 


3% 


13% 


32% 


50% 


Cruise 


4.19 


0.96 


2% 


4% 


14% 


33% 


47% 


Descent 


4.28 


0.87 


1% 


3% 


14% 


32% 


50% 


Terminal Area 


4.29 


0.91 


1% 


3% 


12% 


30% 


53% 


Final Approach 


4.09 


1.10 


3% 


8% 


14% 


26% 


48% 


Ride Reports 


Averages 


Std. Dev. 


%1's 


%2's 


%3's 


%4's 


%5's 


Ground Operations 


3.37 


1.13 


8% 


11% 


34% 


30% 


17% 


Departure 


3.73 


0.94 


2% 


8% 


29% 


40% 


22% 


Cruise 


3.89 


0.89 


1% 


4% 


25% 


43% 


26% 


Descent 


3.70 


0.95 


1% 


9% 


30% 


38% 


22% 


Terminal Area 


3.65 


1.09 


4% 


11% 


28% 


31% 


26% 


Final Approach 


3.52 


1.30 


8% 


17% 


18% 


27% 


29% 


Winds Aloft 


Averages 


Std. Dev. 


%1's 


%2's 


%3's 


%4's 


%5's 


Ground Operations 


2.67 


1.08 


17% 


25% 


37% 


15% 


5% 


Departure 


2.89 


1.08 


11% 


22% 


41% 


16% 


9% 


Cruise 


3.22 


1.07 


6% 


17% 


38% 


26% 


13% 


Descent 


2.64 


1.15 


17% 


33% 


29% 


13% 


8% 


Terminal Area 


2.52 


1.27 


27% 


27% 


24% 


13% 


10% 


Final Approach 


2.40 


1.36 


36% 


23% 


18% 


12% 


11% 


Surface Winds 


Averages 


Std. Dev. 


% l's 


%2's 


%3's 


%4's 


%5's 


Ground Operations 


3.61 


1.58 


5% 


10% 


30% 


35% 


20% 


Departure 


3.00 


1.37 


20% 


17% 


26% 


20% 


18% 


Cruise 


2.54 


1.36 


30% 


23% 


20% 


14% 


12% 


Descent 


3.79 


1.11 


5% 


8% 


20% 


37% 


30% 


Terminal Area 


4.27 


1.82 


2% 


4% 


13% 


36% 


46% 


Final Approach 


4.48 


0.77 


0% 


2% 


8% 


27% 


62% 



101 



Importance Ratings by Phase of Flight (con't) 





Statistics 


Percentage of 


Responses 


; at Each Value 


Next Comm. Freq. 


Averages 


Std. Dev. 


%1's 


%2's 


%3's 


%4's 


%5's 


Ground Operations 


2.80 


1.30 


21% 


21% 


27% 


18% 


12% 


Departure 


3.42 


1.24 


8% 


15% 


26% 


26% 


24% 


Cruise 


3.34 


1.22 


10% 


14% 


29% 


28% 


20% 


Descent 


3.64 


1.21 


7% 


11% 


23% 


29% 


30% 


Terminal Area 


3.86 


1.18 


6% 


8% 


18% 


30% 


38% 


Final Approach 


3.59 


1.36 


12% 


11% 


20% 


22% 


35% 


Error of Controller 


Averages 


Std. Dev. 


%1's 


%2's 


%3's 


%4's 


%5's 


Ground Operations 


4.38 


0.83 


1% 


3% 


11% 


29% 


57% 


Departure 


4.23 


0.91 


1% 


4% 


17% 


29% 


49% 


Cruise 


4.01 


1.02 


2% 


5% 


23% 


28% 


41% 


Descent 


4.19 


0.92 


1% 


4% 


18% 


30% 


47% 


Terminal Area 


4.33 


0.89 


1% 


2% 


14% 


26% 


56% 


Final Approach 


4.41 


0.88 


1% 


3% 


12% 


24% 


61% 


Misc. Elements 
















Ground Operations 


Averages 


Std. Dev. 


%1's 


%2's 


%3's 


%4's 


%5's 


Routing to Runway 


3.60 


1.15 


5% 


12% 


25% 


31% 


26% 


"Hold Short" of Runway 


3.96 


1.09 


3% 


8% 


20% 


28% 


40% 


A/C on Runway 


4.42 


0.89 


1% 


3% 


11% 


21% 


63% 


Descent/T. Area 


Averages 


Std. Dev. 


%1's 


%2's 


%3's 


%4's 


%5's 


Hold Situation (Descent) 


4.28 


0.77 


0% 


1% 


14% 


39% 


45% 


Hold Situation (T. Area) 


4.19 


0.86 


1% 


3% 


15% 


38% 


43% 


Terminal Routing 


4.35 


0.81 


1% 


2% 


11% 


35% 


52% 


Approach Clearance 


4.47 


0.82 


1% 


2% 


8% 


26% 


62% 


Final Approach 


Averages 


Std. Dev. 


%1's 


%2's 


%3's 


%4's 


%5's 


Windshear 


4.76 


0.57 


0% 


0% 


3% 


15% 


81% 


Missed Approach Weather 


4.63 


0.64 


0% 


1% 


4% 


24% 


70% 


Missed Approach Other 


4.27 


0.88 


1% 


4% 


13% 


33% 


50% 


A/C on Runway 


4.83 


0.47 


0% 


0% 


2% 


12% 


86% 


Braking Action 


4.42 


0.77 


0% 


2% 


8% 


32% 


56% 


Taxiway Turnoff 


3.67 


1.04 


4% 


7% 


31% 


33% 


24% 



102 



Appendix E: 

Importance Ratings of Party Line Information from 
Pilots of Different Flight Operations 



103 



Importance Ratings by Pilots of Different Flight 

Operations 





Average 


Percentage of 


Responses 


at Each 


Value 




Rating 


% of 'Vi 


i % of '2'. 


s % of '3's 


% of '4's 


;% of * 


Ground Operations 














General Aviation 


3.79 


4% 


10% 


24% 


27% 


35% 


Commuter Airline 


3.66 


7% 


11% 


24% 


25% 


33% 


Major Airline 


3.70 


7% 


8% 


24% 


30% 


31% 


Military 


3.69 


5% 


12% 


22% 


29% 


31% 


Next Communications 


Frequency 












General Aviation 


3.09 


15% 


19% 


27% 


23% 


17% 


Commuter Airline 


2.64 


25% 


25% 


25% 


13% 


12% 


Major Airline 


2.66 


25% 


20% 


29% 


16% 


9% 


Military 


2.72 


22% 


24% 


27% 


16% 


11% 


Weather Overall 














General Aviation 


3.81 


3% 


8% 


25% 


34% 


30% 


Commuter Airline 


3.67 


7% 


7% 


29% 


27% 


30% 


Major Airline 


3.69 


6% 


5% 


27% 


39% 


23% 


Military 


3.87 


1% 


12% 


17% 


38% 


31% 


Thunderstorms & Deviations 












General Aviation 


4.23 


3% 


6% 


14% 


20% 


58% 


Commuter Airline 


4.23 


4% 


5% 


13% 


21% 


57% 


Major Airline 


4.14 


4% 


3% 


15% 


33% 


45% 


Military 


4.28 


1% 


3% 


16% 


27% 


53% 


Visibility & Ceiling 














General Aviation 


3.93 


3% 


5% 


21% 


36% 


34% 


Commuter Airline 


3.71 


5% 


11% 


21% 


36% 


28% 


Major Airline 


3.62 


7% 


8% 


25% 


33% 


26% 


Military 


4.02 


3% 


7% 


19% 


30% 


42% 


Icing Conditions 














General Aviation 


4.35 


4% 


5% 


9% 


16% 


66% 


Commuter Airline 


3.99 


3% 


11% 


16% 


25% 


45% 


Major Airline 


3.87 


5% 


8% 


19% 


31% 


37% 


Military 


4.16 


1% 


5% 


16% 


32% 


46% 


Ride Reports & Turbulence 












General Aviation 


3.43 


6% 


11% 


36% 


29% 


18% 


Commuter Airline 


3.15 


12% 


11% 


39% 


30% 


9% 


Major Airline 


3.57 


8% 


6% 


29% 


34% 


23% 


Military 


3.17 


6% 


21% 


35% 


27% 


11% 


Winds Aloft 














General Aviation 


3.00 


10% 


20% 


40% 


20% 


10% 


Commuter Airline 


2.43 


22% 


28% 


36% 


12% 


2% 


Major Airline 


2.49 


22% 


27% 


34% 


14% 


3% 


Military 


2.68 


12% 


28% 


43% 


12% 


4% 



104 



Importance Ratings by Pilots of Different Flight 
Operations (Con't) 



Ground Operations (Con't) Average 

Rating 



Percentage of Responses at Each Value 
% of 'l's % of *2*s % of *3's % of *4's % of 'S's 



Surface Winds 














General Aviation 


3.74 


2% 


13% 


31% 


31% 


22% 


Commuter Airline 


3.53 


6% 


10% 


32% 


32% 


21% 


Major Airline 


3.47 


7% 


10% 


30% 


36% 


17% 


Military 


3.77 


3% 


4% 


27% 


43% 


22% 


Routing to Runway 














General Aviation 


3.47 


4% 


16% 


32% 


27% 


22% 


Commuter Airline 


3.71 


4% 


15% 


20% 


28% 


33% 


Major Airline 


3.83 


4% 


7% 


21% 


38% 


30% 


Military 


3.36 


11% 


13% 


25% 


32% 


19% 


Relative Sequencing 














General Aviation 


3.68 


3% 


11% 


27% 


36% 


24% 


Commuter Airline 


3.50 


3% 


12% 


34% 


32% 


18% 


Major Airline 


3.86 


1% 


6% 


36% 


37% 


19% 


Military 


3.36 


4% 


17% 


32% 


32% 


15% 


Aircraft Holding Short of 


Runway 












General Aviation 


3.85 


4% 


9% 


23% 


27% 


37% 


Commuter Airline 


4.12 


2% 


8% 


16% 


26% 


49% 


Major Airline 


4.10 


2% 


5% 


20% 


29% 


45% 


Military 


3.71 


5% 


12% 


18% 


35% 


29% 


Aircraft Crossing Active 


Runway 












General Aviation 


4.35 


1% 


7% 


10% 


23% 


60% 


Commuter Airline 


4.44 


1% 


3% 


13% 


17% 


66% 


Major Airline 


4.44 


1% 


2% 


11% 


22% 


63% 


Military 


4.48 


2% 


1% 


10% 


23% 


65% 


Error of Controller 














General Aviation 


4.30 


1% 


5% 


12% 


28% 


54% 


Commuter Airline 


4.48 


0% 


2% 


13% 


21% 


64% 


Major Airline 


4.40 


0% 


2% 


10% 


31% 


56% 


Military 


4.40 


1% 


2% 


9% 


34% 


55% 



105 



Importance Ratings by Pilots of Different Flight 
Operations (Con't) 





Average 


Percentage of 


Responses 


at Each 


Value 




Rating 


% of *l's % Of '2*! 


s % of '3's 


% of *4's 


; % of •: 


Departure 














General Aviation 


3.95 


3% 


7% 


21% 


30% 


39% 


Commuter Airline 


3.78 


6% 


10% 


21% 


28% 


35% 


Major Airline 


3.78 


6% 


9% 


21% 


30% 


34% 


Military 


3.83 


5% 


8% 


22% 


31% 


34% 


Next Communications Frequency 












General Aviation 


3.70 


4% 


14% 


23% 


28% 


32% 


Commuter Airline 


3.15 


14% 


15% 


32% 


19% 


20% 


Major Airline 


3.19 


11% 


19% 


29% 


23% 


18% 


Military 


3.64 


5% 


13% 


22% 


34% 


27% 


Weather Overall 














General Aviation 


3.90 


2% 


4% 


26% 


40% 


29% 


Commuter Airline 


3.81 


3% 


4% 


29% 


36% 


27% 


Major Airline 


3.91 


3% 


4% 


21% 


42% 


30% 


Military 


3.83 


2% 


7% 


23% 


43% 


25% 


Thunderstorm Buildups & 


Deviations 












General Aviation 


4.38 


1% 


3% 


9% 


34% 


54% 


Commuter Airline 


4.62 


0% 


1% 


4% 


27% 


68% 


Major Airline 


4.45 


1% 


1% 


8% 


33% 


57% 


Military 


4.42 


0% 


2% 


11% 


30% 


57% 


Visibility & Ceiling 














General Aviation 


3.77 


3% 


7% 


28% 


36% 


26% 


Commuter Airline 


3.16 


11% 


20% 


27% 


26% 


16% 


Major Airline 


3.20 


12% 


17% 


27% 


28% 


16% 


Military 


3.40 


7% 


15% 


26% 


34% 


18% 


Icing Conditions 














General Aviation 


4.54 


1% 


1% 


7% 


25% 


66% 


Commuter Airline 


4.25 


2% 


5% 


8% 


38% 


48% 


Major Airline 


4.01 


1% 


6% 


20% 


36% 


36% 


Military 


4.21 


2% 


3% 


16% 


33% 


47% 


Ride Reports & Turbulence 














General Aviation 


3.66 


1% 


8% 


37% 


33% 


21% 


Commuter Airline 


3.61 


2% 


9% 


29% 


50% 


11% 


Major Airline 


4.01 


0% 


5% 


16% 


50% 


28% 


Military 


3.46 


4% 


12% 


36% 


27% 


20% 


Winds Aloft 














General Aviation 


3.16 


7% 


17% 


43% 


19% 


14% 


Commuter Airline 


2.58 


15% 


30% 


40% 


11% 


4% 


Major Airline 


2.75 


14% 


25% 


41% 


13% 


7% 


Military 


2.98 


10% 


20% 


40% 


22% 


8% 



106 



Importance Ratings by Pilots of Different Flight 
Operations (Con't) 



Departure (Con't) 


Average 


Percentage of 


Responses 


at Each 


Value 




Rating 


% of 'l's % of '2'! 


s % of '3's 


% of '4's 


% of ' 


Surface Winds 














General Aviation 


3.08 


16% 


18% 


29% 


19% 


18% 


Commuter Airline 


2.85 


19% 


24% 


24% 


18% 


14% 


Major Airline 


3.02 


21% 


14% 


23% 


24% 


18% 


Military 


2.93 


24% 


14% 


24% 


18% 


19% 


Controlled Traffic 














General Aviation 


4.49 


1% 


2% 


6% 


32% 


60% 


Commuter Airline 


4.46 


1% 


3% 


6% 


30% 


60% 


Major Airline 


4.43 


0% 


2% 


11% 


27% 


60% 


Military 


4.54 


0% 


0% 


6% 


34% 


60% 


Uncontrolled Traffic 














General Aviation 


4.52 


0% 


3% 


8% 


23% 


66% 


Commuter Airline 


4.82 


0% 


1% 


0% 


14% 


85% 


Major Airline 


4.65 


1% 


1% 


5% 


17% 


75% 


Military 


4.54 


0% 


1% 


6% 


31% 


62% 


Relative Sequencing 














General Aviation 


3.96 


3% 


6% 


21% 


36% 


35% 


Commuter Airline 


3.70 


2% 


6% 


33% 


41% 


19% 


Major Airline 


3.64 


4% 


6% 


34% 


36% 


20% 


Military 


3.78 


1% 


6% 


29% 


42% 


22% 


Error of Controller 














General Aviation 


4.16 


2% 


5% 


15% 


32% 


46% 


Commuter Airline 


4.29 


0% 


3% 


18% 


26% 


53% 


Major Airline 


4.22 


1% 


3% 


17% 


29% 


49% 


Military 


4.26 


0% 


1% 


22% 


27% 


50% 



107 



Importance Ratings by Pilots of Different Flight 
Operations (Con't) 





Average 


Percentage of 


Responses 


at Each 


Value 




Rating 


% of Ts 


% of 'V, 


s % of '3*s 


% of '4's 


: % of \ 


Cruise 














General Aviation 


3.91 


4% 


8% 


20% 


28% 


39% 


Commuter Airline 


3.59 


8% 


12% 


23% 


29% 


28% 


Major Airline 


3.52 


9% 


11% 


23% 


31% 


26% 


Military 


3.68 


6% 


9% 


24% 


32% 


29% 


Next Communications Frequency 












General Aviation 


3.78 


4% 


11% 


24% 


30% 


33% 


Commuter Airline 


3.07 


13% 


19% 


30% 


24% 


14% 


Major Airline 


2.98 


14% 


18% 


33% 


24% 


11% 


Military 


3.48 


8% 


9% 


28% 


35% 


19% 


Weather Overall 














General Aviation 


4.02 


2% 


2% 


23% 


42% 


32% 


Commuter Airline 


3.81 


1% 


8% 


28% 


36% 


27% 


Major Airline 


3.71 


3% 


8% 


30% 


35% 


25% 


Military 


3.90 


3% 


3% 


26% 


40% 


29% 


Thunderstorm Buildups & Deviations 












General Aviation 


4.54 


1% 


1% 


8% 


27% 


64% 


Commuter Airline 


4.48 


0% 


2% 


8% 


31% 


59% 


Major Airline 


4.34 


0% 


1% 


11% 


38% 


49% 


Military 


4.43 


0% 


0% 


11% 


35% 


54% 


Visibility & Ceiling 














General Aviation 


3.77 


4% 


10% 


25% 


27% 


34% 


Commuter Airline 


2.85 


18% 


21% 


28% 


20% 


12% 


Major Airline 


2.74 


23% 


22% 


26% 


15% 


14% 


Military 


3.03 


11% 


27% 


24% 


23% 


15% 


Icing Conditions 














General Aviation 


4.60 


1% 


2% 


5% 


22% 


71% 


Commuter Airline 


4.33 


1% 


2% 


10% 


38% 


50% 


Major Airline 


3.77 


3% 


7% 


24% 


40% 


26% 


Military 


4.10 


2% 


5% 


16% 


37% 


41% 


Ride Reports & Turbulence 












General Aviation 


3.78 


2% 


5% 


34% 


33% 


26% 


Commuter Airline 


3.87 


2% 


4% 


23% 


48% 


23% 


Major Airline 


4.15 


0% 


1% 


12% 


54% 


32% 


Military 


3.69 


3% 


7% 


30% 


39% 


21% 


Winds Aloft 














General Aviation 


3.36 


5% 


17% 


35% 


24% 


19% 


Commuter Airline 


2.96 


10% 


20% 


41% 


22% 


7% 


Major Airline 


3.16 


7% 


18% 


38% 


29% 


9% 


Military 


3.33 


5% 


15% 


36% 


29% 


15% 



108 



Importance Ratings by Pilots of Different Flight 
Operations (Con't) 



Cruise (Con't) 


Average 


Percentage of 


Responses 


at Each 


Value 




Rating 


% Of '1*! 


i % of '2' 


s % of '3's 


% of '4' 


s% of ' 


Surface Winds 














General Aviation 


2.94 


21% 


21% 


22% 


17% 


19% 


Commuter Airline 


2.39 


32% 


25% 


23% 


17% 


4% 


Major Airline 


2.24 


40% 


26% 


15% 


12% 


9% 


Military 


2.47 


31% 


24% 


23% 


12% 


11% 


Traffic Avoidance 














General Aviation 


4.42 


3% 


2% 


8% 


27% 


61% 


Commuter Airline 


4.39 


2% 


1% 


10% 


30% 


57% 


Major Airline 


4.17 


2% 


6% 


16% 


26% 


50% 


Military 


4.51 


0% 


3% 


3% 


34% 


59% 


Relative Sequencing 














General Aviation 


3.80 


5% 


6% 


24% 


33% 


32% 


Commuter Airline 


3.19 


8% 


20% 


30% 


30% 


12% 


Major Airline 


3.38 


7% 


16% 


27% 


34% 


17% 


Military 


3.58 


4% 


9% 


34% 


30% 


22% 


Error of Controller 














General Aviation 


3.93 


4% 


10% 


18% 


27% 


42% 


Commuter Airline 


4.10 


0% 


5% 


27% 


20% 


47% 


Major Airline 


4.02 


2% 


4% 


24% 


30% 


40% 


Military 


3.95 


1% 


1% 


31% 


36% 


31% 



109 



Importance Ratings by Pilots of Different Flight 
Operations (Con't) 





Average 


Percentage of 


Responses 


at Each 


Value 




Rating 


% of Ts 


% of 'T, 


s % of '3's 


% of '4's 


; % of *! 


Descent 














General Aviation 


4.11 


2% 


6% 


18% 


29% 


46% 


Commuter Airline 


3.95 


4% 


8% 


18% 


31% 


40% 


Major Airline 


3.93 


4% 


7% 


18% 


34% 


37% 


Military 


4.03 


2% 


6% 


16% 


36% 


39% 


Next Communications 


Frequency 












General Aviation 


3.98 


3% 


6% 


21% 


31% 


39% 


Commuter Airline 


3.40 


9% 


16% 


28% 


22% 


25% 


Major Airline 


3.35 


11% 


13% 


27% 


27% 


21% 


Military 


3.82 


5% 


9% 


18% 


35% 


33% 


Weather Overall 














General Aviation 


3.99 


3% 


3% 


22% 


38% 


34% 


Commuter Airline 


3.98 


1% 


4% 


24% 


39% 


32% 


Major Airline 


4.00 


2% 


2% 


22% 


41% 


33% 


Military 


4.04 


2% 


3% 


15% 


49% 


31% 


Thunderstorm Buildups & Deviations 












General Aviation 


4.54 


0% 


2% 


6% 


28% 


64% 


Commuter Airline 


4.65 


0% 


0% 


4% 


27% 


69% 


Major Airline 


4.49 


0% 


0% 


6% 


36% 


57% 


Military 


4.50 


0% 


1% 


6% 


36% 


57% 


Visibility & Ceiling 














General Aviation 


4.33 


1% 


1% 


15% 


32% 


52% 


Commuter Airline 


3.89 


5% 


5% 


22% 


34% 


34% 


Major Airline 


3.95 


4% 


4% 


20% 


34% 


37% 


Military 


4.28 


0% 


5% 


12% 


32% 


50% 


Icing Conditions 














Genera] Aviation 


4.53 


0% 


1% 


9% 


24% 


65% 


Commuter Airline 


4.42 


1% 


3% 


8% 


30% 


58% 


Major Airline 


4.00 


2% 


5% 


20% 


37% 


36% 


Military 


4.23 


0% 


3% 


13% 


41% 


43% 


Ride Reports & Turbul 


lence 












General Aviation 


3.64 


2% 


9% 


38% 


27% 


25% 


Commuter Airline 


3.78 


1% 


7% 


22% 


55% 


15% 


Major Airline 


3.90 


1% 


5% 


22% 


47% 


25% 


Military 


3.41 


3% 


17% 


35% 


28% 


18% 


Winds Aloft 














General Aviation 


2.99 


10% 


27% 


31% 


17% 


15% 


Commuter Airline 


2.49 


16% 


39% 


28% 


14% 


3% 


Major Airline 


2.42 


22% 


36% 


26% 


10% 


5% 


Military 


2.54 


18% 


34% 


28% 


13% 


6% 



110 



Importance Ratings by Pilots of Different Flight 
Operations (Con't) 



Descent (Con't) 


Average 


Percentage of 


Responses 


at Each 


Value 




Rating 


% of 'l*s 


i % Of '2*! 


s % of '3's 


% of '4's 


; % of ' 


Surface Winds 














General Aviation 


3.99 


2% 


5% 


21% 


36% 


36% 


Commuter Airline 


3.59 


8% 


10% 


25% 


32% 


25% 


Major Airline 


3.60 


9% 


10% 


21% 


34% 


26% 


Military 


3.96 


3% 


6% 


14% 


46% 


31% 


Controlled Traffic 














General Aviation 


4.49 


1% 


2% 


10% 


25% 


64% 


Commuter Airline 


4.40 


1% 


5% 


8% 


27% 


60% 


Major Airline 


4.38 


3% 


2% 


10% 


24% 


61% 


Military 


4.62 


0% 


1% 


2% 


32% 


66% 


Uncontrolled Traffic 














General Aviation 


4.45 


1% 


4% 


8% 


23% 


64% 


Commuter Airline 


4.63 


1% 


3% 


6% 


13% 


78% 


Major Airline 


4.49 


3% 


2% 


8% 


19% 


69% 


Military 


4.55 


0% 


1% 


7% 


28% 


64% 


Relative Sequencing 














General Aviation 


4.09 


1% 


3% 


19% 


40% 


37% 


Commuter Airline 


3.71 


3% 


9% 


22% 


48% 


18% 


Major Airline 


3.89 


1% 


6% 


21% 


49% 


24% 


Military 


4.05 


0% 


2% 


21% 


49% 


29% 


Hold Situation / EFC 


Validity 












General Aviation 


4.26 


0% 


3% 


18% 


29% 


50% 


Commuter Airline 


4.26 


2% 


2% 


12% 


38% 


47% 


Major Airline 


4.31 


0% 


0% 


10% 


47% 


42% 


Military 


4.26 


0% 


1% 


12% 


47% 


40% 


Error of Controller 














General Aviation 


4.09 


2% 


8% 


14% 


29% 


47% 


Commuter Airline 


4.21 


0% 


3% 


23% 


25% 


49% 


Major Airline 


4.25 


0% 


2% 


19% 


32% 


47% 


Military 


4.19 


1% 


0% 


21% 


36% 


42% 



111 



Importance Ratings by Pilots of Different Flight 

Operations (Con't) 



Terminal Area 
General Aviation 
Commuter Airline 
Major Airline 
Military 



Average 
Rating 

4.20 
4.19 
4.12 
4.12 



Percentage of Responses at Each Value 

% of Ts % of ^'s % of '3's % of '4*s % of '5's 



Next Communications Frequency 

General Aviation 4.05 

Commuter Airline 3.75 

Major Airline 3.68 

Military 4.00 



Weather Overall 

General Aviation 
Commuter Airline 
Major Airline 
Military 



3.92 
4.12 
4.18 
4.09 



Thunderstorm Buildups & Deviations 

General Aviation 4.48 

Commuter Airline 4.65 

Major Airline 4.56 

Military 4.42 



Visibility & Ceiling 




General Aviation 


4.51 


Commuter Airline 


4.51 


Major Airline 


4.34 


Military 


4.45 


Icing Conditions 




General Aviation 


4.49 


Commuter Airline 


4.40 


Major Airline 


4.14 


Military 


4.12 


Ride Reports & Turbulence 




General Aviation 


3.74 


Commuter Airline 


3.64 


Major Airline 


3.81 


Military 


3.21 


Winds Aloft 




General Aviation 


2.84 


Commuter Airline 


2.21 


Major Airline 


2.35 


Military 


2.50 



3% 


5% 


14% 


28% 


51% 


4% 


5% 


12% 


28% 


52% 


4% 


5% 


14% 


31% 


46% 


3% 


5% 


13% 


32% 


46% 


4% 


6% 


17% 


27% 


46% 


4% 


12% 


21% 


31% 


31% 


8% 


10% 


22% 


28% 


32% 


5% 


4% 


14% 


38% 


39% 


4% 


4% 


21% 


39% 


32% 


4% 


6% 


12% 


31% 


47% 


2% 


4% 


13% 


37% 


44% 


2% 


5% 


12% 


42% 


38% 


2% 


2% 


7% 


25% 


64% 


0% 


1% 


6% 


20% 


73% 


0% 


1% 


4% 


29% 


64% 


0% 


4% 


9% 


29% 


58% 


1% 


2% 


8% 


27% 


64% 


1% 


0% 


8% 


29% 


62% 


2% 


1% 


11% 


30% 


55% 


0% 


4% 


8% 


29% 


60% 


2% 


3% 


6% 


22% 


67% 


1% 


3% 


9% 


30% 


57% 


1% 


3% 


18% 


35% 


43% 


1% 


6% 


16% 


34% 


43% 


4% 


7% 


32% 


27% 


31% 


4% 


10% 


28% 


37% 


22% 


2% 


11% 


20% 


38% 


29% 


7% 


20% 


35% 


20% 


18% 


18% 


27% 


25% 


15% 


16% 


34% 


28% 


23% 


12% 


3% 


30% 


29% 


24% 


9% 


8% 


30% 


24% 


20% 


18% 


8% 



112 



Importance Ratings by Pilots of Different Flight 
Operations (Con't) 



Terminal Area (Con't) 


Average 


Percentage of 


Responses 


at Each 


Value 




Rating 


% of Ts 


% of '2'! 


s % of '3's 


% of '4's 


;% of * 


Surface Winds 














General Aviation 


4.24 


1% 


2% 


17% 


32% 


48% 


Commuter Airline 


4.32 


1% 


6% 


10% 


27% 


56% 


Major Airline 


4.28 


2% 


6% 


13% 


38% 


41% 


Military 


4.25 


2% 


1% 


10% 


46% 


42% 


Controlled Traffic 














General Aviation 


4.57 


0% 


2% 


4% 


24% 


69% 


Commuter Airline 


4.67 


0% 


2% 


5% 


17% 


76% 


Major Airline 


4.57 


0% 


2% 


8% 


21% 


69% 


Military 


4.69 


0% 


0% 


4% 


22% 


74% 


Uncontrolled Traffic 














General Aviation 


4.50 


1% 


4% 


7% 


24% 


66% 


Commuter Airline 


4.82 


0% 


0% 


2% 


14% 


84% 


Major Airline 


4.62 


2% 


2% 


6% 


15% 


76% 


Military 


4.59 


1% 


0% 


10% 


18% 


71% 


Relative Sequencing 














General Aviation 


4.22 


1% 


4% 


14% 


38% 


45% 


Commuter Airline 


4.15 


2% 


4% 


10% 


48% 


37% 


Major Airline 


4.07 


1% 


1% 


17% 


50% 


31% 


Military 


4.18 


0% 


1% 


17% 


46% 


37% 


Hold Situation / EFC 


Validity 












General Aviation 


4.23 


1% 


3% 


16% 


35% 


46% 


Commuter Airline 


4.24 


2% 


2% 


13% 


38% 


46% 


Major Airline 


4.15 


1% 


4% 


14% 


41% 


40% 


Military 


4.12 


1% 


4% 


15% 


43% 


37% 


Terminal Routing & Runway 












General Aviation 


4.39 


1% 


2% 


11% 


32% 


55% 


Commuter Airline 


4.30 


1% 


3% 


12% 


34% 


50% 


Major Airline 


4.29 


1% 


1% 


12% 


38% 


48% 


Military 


4.41 


1% 


1% 


9% 


35% 


54% 


Approach Clearance 














General Aviation 


4.52 


2% 


1% 


7% 


26% 


65% 


Commuter Airline 


4.46 


2% 


2% 


10% 


21% 


65% 


Major Airline 


4.37 


2% 


2% 


10% 


28% 


58% 


Military 


4.57 


0% 


1% 


5% 


30% 


64% 


Error of Controller 














General Aviation 


4.21 


2% 


6% 


12% 


28% 


52% 


Commuter Airline 


4.53 


0% 


0% 


12% 


23% 


65% 


Major Airline 


4.35 


1% 


1% 


17% 


26% 


55% 


Military 


4.26 


2% 


1% 


17% 


29% 


51% 



113 



Importance Ratings by Pilots of Different Flight 

Operations (Con't) 





Average 


Percentage of 


Responses 


at Each 


Value 




Rating 


% of Ts 


% of '2*i 


s % of '3*s 


% of *4's 


i % of ': 


Final Approach 














General Aviation 


4.16 


4% 


6% 


13% 


23% 


54% 


Commuter Airline 


4.22 


4% 


5% 


12% 


21% 


58% 


Major Airline 


4.17 


4% 


6% 


11% 


26% 


53% 


Military 


4.12 


5% 


6% 


14% 


26% 


50% 


Next Communications Frequency 












General Aviation 


3.69 


11% 


8% 


22% 


22% 


38% 


Commuter Airline 


3.32 


16% 


16% 


20% 


19% 


29% 


Major Airline 


3.60 


11% 


13% 


18% 


22% 


36% 


Military 


3.64 


11% 


8% 


23% 


25% 


34% 


Weather Overall 














General Aviation 


3.63 


9% 


11% 


23% 


24% 


33% 


Commuter Airline 


4.01 


6% 


7% 


16% 


23% 


49% 


Major Airline 


4.04 


3% 


8% 


15% 


30% 


44% 


Military 


3.81 


5% 


8% 


22% 


31% 


34% 


Thunderstorm Buildups & 


Deviations 












General Aviation 


4.14 


5% 


6% 


11% 


28% 


51% 


Commuter Airline 


4.48 


1% 


4% 


11% 


15% 


70% 


Major Airline 


4.37 


4% 


2% 


9% 


23% 


62% 


Military 


4.05 


3% 


8% 


20% 


20% 


49% 


Visibility & Ceiling 














General Aviation 


4.64 


1% 


1% 


6% 


19% 


74% 


Commuter Airline 


4.59 


1% 


2% 


8% 


16% 


74% 


Major Airline 


4.44 


2% 


2% 


9% 


25% 


62% 


Military 


4.91 


1% 


4% 


7% 


25% 


64% 


Icing Conditions 














General Aviation 


4.23 


3% 


7% 


13% 


19% 


58% 


Commuter Airline 


4.23 


2% 


8% 


14% 


19% 


57% 


Major Airline 


4.01 


3% 


10% 


13% 


32% 


43% 


Military 


3.83 


4% 


9% 


20% 


32% 


34% 


Ride Reports & Turbulence 














General Aviation 


3.61 


5% 


17% 


21% 


25% 


32% 


Commuter Airline 


3.62 


8% 


12% 


18% 


36% 


27% 


Major Airline 


3.67 


7% 


16% 


13% 


29% 


34% 


Military 


3.01 


17% 


23% 


21% 


20% 


19% 


Winds Aloft 














General Aviation 


2.65 


29% 


25% 


16% 


14% 


17% 


Commuter Airline 


2.25 


39% 


22% 


21% 


12% 


7% 


Major Airline 


2.34 


37% 


23% 


17% 


12% 


10% 


Military 


2.16 


42% 


23% 


18% 


10% 


7% 



114 



Importance Ratings by Pilots of Different Flight 
Operations (Con't) 



Final Approach (Con't) 


Average 


Percentage of 


Responses 


at Each 


Value 




Rating 


% of 'l's 


% of 'V, 


s % of '3's 


% of '4's 


>% of • 


Windshear 














General Aviation 


4.69 


0% 


1% 


5% 


20% 


75% 


Commuter Airline 


4.79 


1% 


0% 


3% 


12% 


85% 


Major Airline 


4.78 


1% 


0% 


2% 


12% 


84% 


Military 


4.82 


0% 


1% 


1% 


13% 


85% 


Surface Winds 














General Aviation 


4.55 


0% 


2% 


8% 


24% 


66% 


Commuter Airline 


4.54 


1% 


1% 


10% 


20% 


69% 


Major Airline 


4.37 


1% 


3% 


10% 


30% 


56% 


Military 


4.54 


0% 


2% 


4% 


32% 


62% 


Controlled Airports 














General Aviation 


4.56 


2% 


2% 


7% 


18% 


72% 


Commuter Airline 


4.68 


1% 


1% 


3% 


19% 


76% 


Major Airline 


4.57 


1% 


2% 


8% 


17% 


72% 


Military 


4.49 


0% 


1% 


15% 


19% 


66% 


Uncontrolled Airports 














General Aviation 


4.53 


2% 


3% 


8% 


16% 


72% 


Commuter Airline 


4.88 


0% 


0% 


1% 


10% 


89% 


Major Airline 


4.59 


2% 


2% 


5% 


16% 


75% 


Military 


4.48 


1% 


1% 


14% 


18% 


66% 


Missed Approach • Weather 














General Aviation 


4.66 


0% 


1% 


4% 


19% 


75% 


Commuter Airline 


4.59 


0% 


1% 


6% 


27% 


66% 


Major Airline 


4.57 


0% 


1% 


4% 


29% 


65% 


Military 


4.72 


0% 


0% 


3% 


22% 


75% 


Missed Approach • Other 














General Aviation 


4.26 


1% 


4% 


15% 


27% 


53% 


Commuter Airline 


4.26 


1% 


5% 


14% 


28% 


52% 


Major Airline 


4.23 


0% 


4% 


13% 


37% 


46% 


Military 


4.32 


1% 


3% 


10% 


37% 


50% 


Aircraft on Landing Runway 














General Aviation 


4.79 


0% 


0% 


2% 


13% 


84% 


Commuter Airline 


4.88 


0% 


0% 


1% 


10% 


89% 


Major Airline 


4.82 


0% 


0% 


2% 


13% 


85% 


Military 


4.84 


1% 


0% 


1% 


10% 


88% 


Braking Action 














General Aviation 


4.19 


1% 


4% 


16% 


34% 


45% 


Commuter Airline 


4.58 


0% 


2% 


5% 


26% 


67% 


Major Airline 


4.57 


0% 


2% 


2% 


33% 


63% 


Military 


4.41 


1% 


1% 


10% 


33% 


55% 



115 



Importance Ratings by Pilots of Different Flight 

Operations (Con't) 



Final Approach (Con't) 


Average 


Percentage of 


Responses 


at Each 


Value 




Rating 


% of 'l*s 


% Of '2'! 


s % of '3's 


% of *4*s 


% of * 


Taxiway Turnoff 














General Aviation 


3.60 


5% 


6% 


36% 


29% 


24% 


Commuter Airline 


3.79 


1% 


7% 


32% 


32% 


28% 


Major Airline 


3.69 


3% 


8% 


29% 


36% 


23% 


Military 


3.63 


5% 


7% 


29% 


36% 


23% 


Relative Sequencing 














General Aviation 


4.12 


2% 


5% 


16% 


36% 


42% 


Commuter Airline 


4.02 


4% 


5% 


17% 


35% 


40% 


Major Airline 


3.99 


1% 


4% 


17% 


49% 


29% 


Military 


4.06 


1% 


3% 


17% 


46% 


33% 


Error of Controller 














General Aviation 


4.34 


3% 


4% 


11% 


19% 


63% 


Commuter Airline 


4.43 


0% 


3% 


13% 


21% 


62% 


Major Airline 


4.43 


0% 


3% 


13% 


24% 


61% 


Military 


4.37 


1% 


1% 


11% 


34% 


53% 



116 



Importance Ratings by Pilots of Different Flight 
Operations (Con't) 



Prosodic PLI Elements 
Sector Congestion 



Average Percentage of Responses at Each Value 

Rating % of 'l's % of '2's % of *3's % of '4's % of *5's 



General Aviation 


3.87 


1% 


6% 


19% 


56% 


19% 


Commuter Airline 


3.94 


2% 


6% 


14% 


53% 


25% 


Major Airline 


3.93 


0% 


5% 


23% 


48% 


25% 


Military 


4.04 


1% 


3% 


24% 


53% 


19% 


Controller Experience 














General Aviation 


3.83 


1% 


7% 


23% 


47% 


23% 


Commuter Airline 


3.93 


2% 


8% 


20% 


38% 


33% 


Major Airline 


3.83 


1% 


6% 


26% 


42% 


25% 


Military 


3.85 


0% 


8% 


25% 


42% 


26% 


Other Pilot's Experience 














General Aviation 


3.67 


3% 


7% 


33% 


37% 


21% 


Commuter Airline 


3.85 


2% 


8% 


18% 


47% 


25% 


Major Airline 


3.45 


5% 


9% 


35% 


35% 


15% 


Military 


3.38 


4% 


15% 


38% 


26% 


17% 


Controller's Level of Urgency 












General Aviation 


4.34 


2% 


1% 


9% 


40% 


49% 


Commuter Airline 


4.29 


0% 


3% 


15% 


33% 


49% 


Major Airline 


4.39 


0% 


2% 


7% 


40% 


51% 


Military 


4.19 


0% 


2% 


15% 


45% 


38% 


Other Pilot's Level of Urgency 












General Aviation 


4.03 


1% 


3% 


23% 


40% 


34% 


Commuter Airline 


4.06 


0% 


5% 


25% 


28% 


42% 


Major Airline 


3.99 


2% 


6% 


20% 


36% 


37% 


Military 


3.88 


0% 


7% 


25% 


42% 


26% 


Background Reassurance 














General Aviation 


3.89 


2% 


7% 


24% 


36% 


32% 


Commuter Airline 


3.48 


5% 


13% 


30% 


36% 


17% 


Major Airline 


3.43 


8% 


10% 


28% 


41% 


14% 


Military 


3.55 


3% 


9% 


34% 


35% 


18% 


Call Sign Confusion 














General Aviation 


4.50 


1% 


4% 


7% 


23% 


66% 


Commuter Airline 


4.61 


1% 


0% 


5% 


26% 


68% 


Major Airline 


4.54 


0% 


1% 


9% 


25% 


65% 


Military 


4.47 


0% 


3% 


4% 


36% 


57% 


ATC Problem or Lost Communication 












General Aviation 


4.50 


0% 


2% 


8% 


29% 


61% 


Commuter Airline 


4.41 


0% 


1% 


13% 


30% 


56% 


Major Airline 


4.26 


1% 


2% 


13% 


35% 


48% 


Military 


4.35 


0% 


1% 


9% 


45% 


45% 


Navaid Problems 














General Aviation 


4.29 


0% 


3% 


15% 


33% 


50% 


Commuter Airline 


4.36 


0% 


2% 


11% 


36% 


51% 


Major Airline 


3.90 


3% 


7% 


23% 


33% 


34% 


Military 


4.28 


0% 


1% 


15% 


40% 


44% 



117 



Appendix F: 
Subjective Responses 



118 



What Does the "Big Picture" Mean to You? 



Traffic Situation 

Weather Situation 

Predict and Plan Ahead 

Safety 

Communication 

Alternate Courses 

Competence of Others 



Overall 


G. Aviation 


Commuter 


Major Airline 


Military 


49% 


54% 


46% 


43% 


62% 


29% 


37% 


21% 


25% 


33% 


16% 


17% 


18% 


18% 


18% 


6% 


7% 


6% 


6% 


3% 


6% 


11% 


5% 


1% 


9% 


3% 


3% 


4% 


3% 


6% 


4% 


4% 


3% 


4% 


6% 



What is the Preferable Mix of Voice (5) and Datalink 
Communications (1) ? 





Overall 


G. Aviation 


Commuter 


Major Airline 


Military 


Datalink/Voice Mix 


3.45 


3.56 


3.27 


3.26 


3.38 


Improved Datalink 


3.10 


3.21 


2.87 


2.97 


2.99 



What Information Would You Like Provided by Datalink? 





Overall 


G. Aviation 


Commuter 


Major Airline 


Military 


Weather Info 


20% 


27% 


29% 


25% 


40% 


Clearances 


14% 


19% 


27% 


24% 


23% 


Nearby Aircraft 


12% 


14% 


16% 


14% 


15% 


Course Changes 


7% 


10% 


9% 


9% 


9% 


Frequencies 


5% 


8% 


4% 


7% 


9% 


Altitude 


5% 


8% 


6% 


7% 


5% 


requency Dialogue 


2% 


3% 


4% 


3% 


2% 


Airport Layout 


2% 


2% 


4% 


2% 


2% 



119