The Peripheral Vision Display (PVD) which presents the pilot with a gyro stabilized artificial horizon projected onto his instrument panel by a laser light source is outlined. During instrument flight conditions, such a display allows the pilot to gain attitude awareness by sensing the horizon line through his peripheral vision. The pilot can detect changes to aircraft attitude without continuously referring back to his flight instruments. A second generation PVD unit was installed in the USAF/Calspan NT-33A during late 1982. An NT-33A flight evaluation of the display provides a unique opportunity to utilize a Workload Assessment Device (WAD) to obtain quantitative data regarding the utility of the PVD in reducing pilot workload. The experimental design and procedures for a two phase NT-33 PVD flight evaluation program is described

Knotts, L.

English

NASA Technical Reports Server

Paper 11 
EXTRACTS FROM THE TEST PLAN FOR IN-FLIGHT EVALUATION 
OF THE NT-33A PERIPHERAL VISION DISPLAY 
Louis H. Knotts 
Flight Research Department 
ARVIN/CALSPAN 
Buffalo, New York 
INTRODUCTION 
The Peripheral Vision Display (PVD) presents the pilot with a gyro stabilized 
artificial horizon projected onto his instrument panel by means of a laser light 
source. During instrument flight conditions, such a display allows the pilot to gain 
attitude awareness by sensing the horizon line through his peripheral vision. The 
pilot can therefore detect changes to aircraft attitude without continuously refer- 
ring back to his flight instruments. 
A second generation PVD unit was installed in the USAF/Calspan NT-33A during late 
1982. An NT-33A flight evaluation of the display provides a unique opportunity to 
utilize a Workload Assessment Device (WAD) to obtain quantitative data regarding the 
utility of the PVD in reducing pilot workload. 
This test plan describes the experimental design and procedures for a two phase 
NT-33 PVD flight evaluation program. Six NT-33 flights will be flown at Buffalo, N.Y. 
during February 1983. These flights will consist of a calibration flight, a familiar- 
ization flight, and four data flights. The second phase of the PVD evaluation program 
will be flown at Edwards AFB during April 1983. Approximately two familiarization 
flights and six data flights will be flown at this time. 
The general nature of the experiment covered by this test plan is as follows. 
The evaluation pilot (EP) flies the NT-33 in simulated instrument conditions created 
by means of a hood covering the front cockpit. He is tasked with performing a series 
of mild instrument maneuvers which emphasize angle of bank control. The NT-33 vari- 
able stability system (VSS) is used to provide the aircraft with a lightly damped 
Dutch roll with a high roll-to-yaw ratio. A mild random disturbance is introduced 
into the three aircraft axes by means of the VSS. The Workload Assessment Device 
(WAD) generates a random sequence of letters which are displayed on a readout located 
below the pilot's instrument panel. The evaluation pilot must respond to these let- 
ters with a 'yes' or 'no' as quickly as possible by pressing the appropriate cockpit 
button. His answers and reaction times are recorded by the WAD and are processed to 
determine pilot workload. The above tasks are performed with the PVD alternately on 
and then off. Differences in WAD data are used to quantify changes in pilot workload 
due to the Peripheral Vision Display. 
103 
https://ntrs.nasa.gov/search.jsp?R=19850001748 2020-03-20T21:44:39+00:00Z
OBJECTIVES 
The objectives of the PVD flight evaluation program in the NT-33 are as follows: 
0 To obtain quantitative data regarding the utility of the PVD in reducing 
pilot workload during a high workload instrument flight environment; and 
0 To determine if the PVD improves pilot performance in eliminating large 
excursions from the desired aircraft attitude. 
SCHEDULE 
The following table shows the approximate dates, location, and purpose of all PVD 
evaluation program flights. Each flight will be of 1.5 hours duration. Chase air- 
craft flights are also included on the schedule. 
Table 1 
PVD Flight Evaluation Program Schedule 
DATE 
2-9 Feb 83 
7-18 Feb 83 
LOCATION 
Buffalo 
Buffalo 
MISSION 
29 Mar-8 Apr 83 Edwards AFB 
NT-33 FLT. HRS. 
1 calibration flight 
1 familiarization flight 
4 data flights 
5 chase flights 
2 familiarization flights 
6 data flights 
8 chase flights 
CHASE FLT. HRS. 
Buffalo: 9.0 Buffalo: 7.5 
Edwards: 12.0 Edwards: 12.0 
Total: 21.0 Total: 19.5 
PROJECT PILOTS 
The number of PVD project evaluation pilots will be kept small 
FLT. HRS. 
1.5 hr 
1.5 hr 
6.0 hr 
7.5 hr 
3.0 hr 
9.0 hr 
12.0 hr 
in order to allow 
each pilot to fly several data flights. This will enable each pilot to gain suf- 
ficient experience with the PVD to learn to use the display to its best advantage. 
The evaluation pilot who will take part in the PVD flights at Buffalo is Captain 
A. Lamoureaux, Canadian Forces. 
During the flights at Edwards AFB, two Air Force Test Pilot School staff pilots, 
Major Lawrence Davis and Major Wayne Staley, will serve as evaluation pilots. 
The NT-33 safety pilot will be from the Calspan engineering pilot staff. 
104 
TEST SYSTEM 
NT-33A AIRCRAFT: 
The test aircraft is the USAF/Calspan NT-33A in-flight simulator (Reference 1) 
operated by Calspan under contract to the USAF Flight Dynamics Laboratory. The 
NT-33A variable stability system (VSS) uses a response feedback technique to generate 
the dynamic response of the simulated aircraft. In this program the VSS will be set 
to provide Level 1 flying qualities in the longitudinal axis. The lateral/directional 
axes will be programmed to create a lightly damped Dutch roll (5 = 0.1) with a high 
roll-to-yaw ratio (Q/B = 3.5). The variable stability system gains are scheduled 
with aircraft fuel quantity so that the dynamics remain constant throughout the 
flight. 
A special circuit is available on the NT-33 which creates random disturbance 
inputs that can be entered into any of the VSS control axes. In this way a low level 
disturbance can be created and added to the aircraft's three axes to further compli- 
cate the evaluation pilot's flying task. The level of this turbulence is scaled to 
the NT-33's changing moments of inertia as fuel is consumed. 
To simulate instrument flight conditions, and at the same time to darken the 
cockpit sufficiently to enable the evaluation pilot to see the PVD laser line under 
bright ambient light conditions, a hood will be manufactured for the front cockpit of 
the NT-33. Since this hood will severely limit the forward visibility of the rear 
seat safety pilot, the hood will be used only during in-flight evaluation of the PVD 
and taken down for take-off and landing. 
The programmable Head-Up-Display will be removed from the NT-33 front cockpit 
during the PVD evaluation program. In the center front instrument panel a 5" atti- 
tude indicator will be installed. This will provide a conventional head down instru- 
ment scan pattern for the evaluation pilot. 
WORKLOAD ASSESSMENT DEVICE: 
The Workload Assessment Device (WAD) was developed by Systems Research Labora- 
tories, Inc. (SRL) for the Systems Engineering Test Directorate of the Naval Air Test 
Center (NATC). The device consists of a processor and recording system located in 
the nose of the aircraft, a display system in the front cockpit, and a control ter- 
minal in the rear cockpit. The processor generates a random sequence of letters 
which are presented to the evaluation pilot either visually on the HUD or aurally 
over the pilot's intercom. During this program the visuai presentation mode will be 
utilized; however, the WAD letters will be displayed on a small Liquid Crystal Diode 
(LCD) display below the front instrument panel instead of on the HUD. To control the 
WAD system, a handheld keyboard terminal is mounted to the rear cockpit left instru- 
ment panel. The WAD recording system uses a small cassette to record workload meas- 
urement data as well as up to 16 channels of other flight parameters. 
During the workload test, the WAD presents one letter at a time to the evaluation 
pilot at a random interval of from 2 to 15 seconds- The mean inter-stimulus interval 
(ISI) will be set to 5 seconds, so that during a four minute evaluation approximately 
50 letters will be presented to the evaluation pilot. While the pilot performs his 
primary flying tasks, he must also note each WAD letter and determine whether it is a 
105 
member of his "positive" set of letters (called MSETS) which he memorized prior to 
flight. He must perform this secondary task of responding to the WAD letters as 
quickly and accurately as possible; however, he must not let his response to the WAD 
degrade his primary piloting tasks. The evaluation pilot responds to each letter by 
pulling the control stick trigger when a letter is "positive' (that is, a member of 
his set) or depressing the upper stick button when the letter is "negative" (that is, 
not a member of his memorized set). As soon as the pilot responds, either correctly 
or incorrectly, the letter disappears. If a response is not received within a set 
period of time, a time-out error response is logged. Four different sizes of "posi- 
tive" letter sets, containing zero, one, two, and four letters (MSETO through MSETI, 
respectively) are used to obtain a complete workload evaluation. The zero letter set 
is a baseline in that no mental "sorting" is required for the evaluation pilot to 
respond - every letter is "negative." As the positive letter set size increases from 
one to four, more processing time is required by the evaluation pilot to determine if 
a letter is "positive" or "negative." Further information concerning use of the 
Workload Assessment Device can be found in Reference 2. 
PERIPHERAL VISION DISPLAY: 
The Peripheral Vision Display (PVD) or Malcolm Horizon was manufactured by 
Garrett Manufacturing, Ltd. for the Canadian Forces. The display provides a large 
horizon line which allows the pilot to maintain aircraft attitude without looking 
directly at his gyro reference. The PVD horizon line is produced by a Helium-Neon 
laser which rapidly sweeps across the instrument panel. This line remains parallel 
with the outside horizon through 360 degrees of aircraft roll. The line also moves 
in pitch to reflect aircraft pitch attitude changes. A switch is available to the 
evaluation pilot which allows him to select l:l, 1:2, or 1:3 pitch scaling of the 
PVD line with respect to true pitch attitude. During this workload study, the 
1:3 pitch scale will be used. 
Other controls available to the evaluation pilot include a roll trim and pitch 
trim adjustment, a brightness control, and an on/off switch. The evaluation pilot 
switches are located on a remote control unit attached to the front cockpit left 
canopy rail. Other system components include a processor unit located above the 
safety pilot's instrument panel, and a laser projector located above and behind the 
evaluation pilot's right shoulder. Details of the PVD installation in the NT-33A 
can be found in References 3 and 4. 
INSTRUMENTATION: 
The 28-channel NT-33A digital tape recorder can record pilot control forces and 
displacements, aircraft response variables such as angles, angular rates, accelera- 
tions, and altitude. 
A voice tape recorder is available for use during the PVD workload program. The 
voice recorder will be left on throughout each PVD evaluation to record pilot com- 
ments, WAD letters, and external distractions. 
The Workload Assessment Device will record the evaluation pilot's responses to 
the visual letters as well as his reaction times. In addition, aircraft angle of 
106 
bank information will be recorded at a rate of 4 samples per second using one of the 
16 available analog-to-digital recording channels. 
FLIGHT TEST PROCEDURES 
FAMILIARIZATION FLIGHTS: 
The first flight that each evaluation pilot receives during this program will be 
a familiarization flight. The purposes of the familiarization flights are to: 
e expose the evaluation pilot to routine NT-33 procedures; 
0 practice PVD, WAD, and VSS procedures; 
0 practice performing the instrument maneuvers; 
0 gain familiarity with use of the PVD; and 
0 collect preliminary PVD workload data. 
Inflight procedures for the familiarization flights will be very similar to the 
evaluation flight procedures. Fewer WAD data runs will be performed on the famil- 
iarization flights than on subsequent data flights so that the evaluation pilot can 
devote more time to instrument maneuvering using the PVD. 
EVALUATION FLIGHTS: 
Each PVD data flight will consist of ten workload measurement evaluations. Each 
evaluation will consist of a four minute instrument maneuvering primary task concur- 
rent with a WAD secondary task. The primary task requires the evaluation pilot to 
maintain a constant airspeed and altitude while accomplishing a sequence of constant 
angles of bank. As these maneuvers are performed the evaluation pilot must alter his 
instrument scan to allow him to observe the WAD letter display as much as possible 
without degrading his maneuvering task. 
Four runs of the primary task are performed with the PVD turned off and another 
four runs are performed with the PVD turned on. During these runs the WAD 0, 1, 2, 
and 4 member letter sets are each used once. 
Detailed flight cards will be generated for each flight, however, the following 
steps will help clarify the procedures for a typical evaluation flight. 
0 Cruise flight is established above 10,000' MSL at 250 KIAS. 
0 Front cockpit hood installed. 
0 PVD turned off. 
0 VSS engaged, evaluation pilot (EP) flies NT-33 with unstable spiral. 
107 
0 Artificial lateral turbulence turned on (if required). 
0 Safety pilot (SP) turns on digital recorder, voice recorder, starts WAD. 
0 EP starts clock for 4 minute task. 
0 EP performs maneuvering primary task and responds to WAD secondary task. 
0 At end of 4 minutes, SP takes control of aircraft, stops WAD, turns off 
digital recorder, maneuvers to remain in designated airspace. 
0 EP makes comments concerning run, resets clock. 
0 Procedures are repeated until 4 runs are made using WAD MSETS 0, 1, 2, and 4. 
0 EP turns on PVD. 
0 Procedures are repeated for 4 more runs using WAD MSETS 0, 1, 2, and 4. 
0 Front cockpit hood removed. 
0 Return to base. 
EVALUATION TASK: 
j? 
The instrument maneuvering task which will be used during the PVD evaluation 
program will emphasize holding a set aircraft attitude for fairly long periods of 
time. The task will be coordinated with the clock so that the pilot's instrument 
scan will concentrate on aircraft attitude, airspeed, altitude, and time, with as 
much scan to the WAD visual letter display as is possible. With the PVD turned on, 
the pilot can set his precise attitude using the attitude indicator, and then rely 
on peripheral cues from the PVD horizon bar to warn him of changes to the set air- 
craft attitude. This may allow the pilot to devote more attention to the WAD visual 
display. 
The sequence of specified angles of bank for the primary instrument task will be 
simple to avoid the necessity of having the evaluation pilot refer to an in-flight 
instruction card during the task. The following instrument task, or variations 
thereof, will be used for the PVD evaluation. 
0 Maintain 250 KIAS and constant altitude throughout the maneuver. 
0 First minute: hold wings level. 
0 Second minute: hold 30° bank to the left. 
0 Third minute: hold 30° bank to the right. 
0 Fourth minute: hold wings level. 
108 
TEST DATA 
The most significant data collected during the PVD evaluation flights will be the 
workload information recorded on the WAD cassette recorder and the aircraft response 
data collected on the NT-33 digital recorder. 
The Workload Assessment Device recorder provides information concerning the let- 
ters presented to the pilot as a secondary task, the responses made'by the pilot, and 
the time it took the pilot to respond. Discrete angle of bank information will also 
be recorded by the WAD, but this information is intended primarily as a backup to the 
NT-33 digital recorder. Statistical reduction and print out of the WAD data can be 
accomplished using the WAD portable ground support unit. Interpretation and analysis 
of the workload data will be accomplished under the direction of Dr. Samuel Schiflett 
of the Naval Air Test Center. 
Data concerning pilot performance in maintaining the desired aircraft flight con- 
dition will be collected by the NT-33 digital recorder. Angle of bank, pitch atti- 
tude, and altitude excursions are of primary interest in determining pilot perform- 
ance during the instrument flight maneuvers. Time histories of appropriate param- 
eters can be made using the "Quicklook" digital playback system located at the USAF 
Test Pilot School and at Calspan. 
The voice recordings made during PVD evaluations will be reviewed to obtain pilot 
comments concerning workload, utility of the PVD, operation of the Workload Assess- 
ment Device, and whether external distractions interfered with any of the data runs. 
REFERENCES 
1. Hall, G. W. and Huber, R. W.: "System Description and Performance Data for the 
USAF/Calspan Variable Stability T-33 Airplane," Calspan Report No. BM-2821-F-2, 
July 1970. 
2. Schiflett, S. G.: "Evaluation of a Pilot Workload Assessment Device to Test 
Alternate Display Formats and Control Handling Qualities," NATC Report SY-33R-80, 
1980. 
3. Huber, R. W.: "Class II Modification Documentation for Malcolm Horizon 
Peripheral Vision Horizon Device, Part I", T-33 Technical Memo No. 197, 
October 1981. 
4. Huber, R. W.: "Class II Modification Documentation for Malcolm Horizon 
Peripheral Vision Horizon Device, Part II", T-33 Technical Memo No. 213, 
September 1982. 
5. Huber, R. W. and Parrag, M. L.: "Flight Manual Supplement for the USAF/Calspan 
NT-33A 51-4120 Variable Stability Aircraft, T.O. It-33A-1 Supplement, Revision B", 
Calspan T-33 Memo No. 78, June 1979. 
109 


Extracts from the test plan for in-flight evaluation of the NT-33A peripheral vision display

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server