traditionally given to prospective controllers.
The irregularities apparent in the separate sub-
task curves presented above, although no doubt in
part a function of the small number of measures
represented at each point, can be taken as evidence
for the struggle for whole-task learning that
involves subtask integration. Initially success at
monitoring one subtask may mean that another
subtask is being monitored poorly. Failure to re-
spond to entries or handoffs provokes a buzzer that
can motivate the subjects in future problems to try
to reduce the number of missed signals. Gen-
erally, initial performance appears disorganized
with the subject switching his concentration from
one subtask to another as he becomes aware of his
errors. Later, with experience at the task, he re-
fines his approach, develops search patterns, and
organizes his activities.

In accord with the above logic, a simpler, less-
expensive version of the task could be considered
for facility testing, with a minimum amount of
attention required by training personnel. For
example, a filmstrip projector is manufactured
with a record-player attachment that employs
prerecorded, inaudible tones to advance the film.
Animated filmstrips and phonograph records con-
taining hypothetical, synchronized pilot com-
munications could be produced in quantity for dis-
tribution to and circulation among facilities.
There, such materials could be used in automated
training of groups of controllers who would be
required to detect conflictions, practice proper use
of strip-marking or phraseologies, identify errone-
ous position reports, etc.

To extend our own test-program capability, we
have recently made use of an optical, photo-
graphic technique. The equipment produces new
filmstrips from the masters at any desired angle
of rotation. With three rotations, for example,
we effectively have four programs with identical
target workloads, differing only in terms of the
appearance of airways and of the direction of

12

target movement. Tape-recorded audio com-
munications and flightstrip notations, except for
location identifiers, do not have to be revised.
Such a capability now permits day-to-day com-
parison of performance under comparable en-
vironmental and task conditions, while controlling
for possible memory effects.

Tnitial experience with the task system dictated
two desirable changes. The first was replacement
of the console-mounted projectors with television
monitors. This alleviates two problems: (a)
noise from the projector relay that could serve as
a cue to the subject of the change in display; (b)
the considerable time and effort required to change
filmstrips at all six consoles between hourly tests.
Filmstrips are projected directly into a television
camera for distribution to the monitors. The
second change involved eliminating the use of the
traditional flightstrip holder and going to a new
card format that can be inserted into spring-clip
fasteners on the plastic strip area located in the
auxiliary display panel (see Figure 2). We have
found that the flightstrips used initially required
a good deal of “busy-work” (e.g., handling and
marking) that appeared to detract from the op-
erator’s efficiency, thereby precluding a purer un-
derstanding of his critical task behaviors.

To date, interests of systems engineers and op-
erations personnel have suggested several other
uses for the system in studies related to controller
proficiency, including research on target character-
istics such as size and sharpness, workload as a
function of number of targets and speed (eg.,
supersonic transport) of targets, control tech-
niques and sector arrangement, and display de-
sign. In particular, we feel that experience with
the system will contribute to human-engineering
knowledge in the particular area of work stations,
insofar as it involves such questions as how does
one design displays to attract attention, what pat-
tern of efficient search can be recommended, and
what is the optimum layout of displays.




Ficure 2. Radar ATC task console.

The animation technique involved still photog-
raphy, using a Robot 18MB filmstrip camera, of
small metal chips set on a flat-black, 19-in.-diam-
eter circle of cardboard, with airways being repre-
sented by strips of ¢-in.-wide, red chart tape.
Processing of the Plus X film used was in modi-
fied DK 50-1:1. The metal chips were appro-
priately painted with bands of white, black, and
shades of gray to simulate trails from which air-
speed and direction of travel could be inferred.
A magnetic backing to the chips permitted ac-
curate positioning to the cardboard mounted upon
thin sheet metal. For each photograph, targets
were advanced individually by hand using plastic
index strips calibrated for airspeeds ranging from
300 to 600 knots. The range represented by the
control sector was established as 100 mi.

Filmstrips are rear-projected from a distance
of 27 in. onto Polacoat lenscreen using a DuKane
Model 57647B projector equipped with a Buhl
Microwide 612-380 lens. Filmstrip advance is
programmed to occur every 10 sec and is accom-

plished rapidly by Geneva mechanism. The
radar visual display appears within a 11-94-in.-
diameter circle.

Traditional flightstrips give flight plan and al-
titude information. Aireraft carry fictional iden-
tifications (e.g., HR=Horizon, DX=Dixie) to
eliminate familiar associations. Flightstrips for
“active” aircraft are placed in a small rack in front
of the operator, while those not current are stored
to the right in a bay slanted at 60°.

The auxiliary display panel located to the right
of the radar screen contains indicators that are to
be associated with up to six aircraft targets. A
green flashing light in the first column announces
the “entry” of a new aircraft. Pressing the indi-
cator stops the flashing light and, in turn, illumi-
nates an adjacent, numbered “beacon-code” indi-
cator. This is followed, shortly, by the activation
of a digital readout indicating the flight altitude
(in thousand feet) of the aircraft. Programmed
altitudes vary from 11,000 to 22,000 ft. If the
displayed altitude should change during the prob-



MX166;

Taste A2. Flightsirip data: Sample ATC problem.

9 SE191; 24; B707; 550; 1514 UNC, 1519 SIE; ABQ V16 ATL; 15

HR222; 21;

EN410; 21; L188; 400; 1501 SIE, 1506 UNC; MEM V16, AMA; 18
PA920; 22; B727, 500; 1501 ROM, 1505 OSC; ABQ V10 CLE; 19
MW339; 23; DC8; 450; 1502 OSC, 1511 SIE; STL V18 FTW; 20
TR141; 25; B707; 550; 1504 UNC, 1507 TAN, 1514 ROM; DAL V14 V12 MKC; 21
BR950; 24; B707; 600; 1505 TAN, 1510 ROM; AMA V12 MKC; 17
6; DC8; 450; 1508 USC, 1516 SIE; STL V18 DAL; 16
DX375; 22; L188; 400; 1513 TAN, 1519 UNC; ABQ V14 DAL; 12
HR882; 21; B727; 500; 1513 SIE, 1520 OSC; DAL V20 V18 CHI; 17

A11038; 23; B52; 450; 1517 ROM, 1525 TAN; MKC V12 AMA; 16
EN211; 25; B707; 550; 1520 OSC, 1525 ROM; CLE V10 ABQ; 18
TRA412; 26; CV88; 550; 1523 SIH, 1530 OSC; DAL V20 V18 CHI; 19
HR113; 24; L188; 400; 1523 OSC, 1520 ROM; ABQ V10 V12 STL; 14
MW314; 22; DC7; 350; 1528 TAN; CHI V14 V12 DAL; 20

61588; 21; TV; 450; 1529 UNC, 1533 SIE; AMA V16 ATL; 13
BR416; 23; CRVL; 450; 1532 SIE; AMA V20 V16 STL; 15
81779; 25; B707; 500; 1530 UNC, 1535 TAN; DAL V14 MKC; 19
PA1I8; 24; DC8; 500; 1530 ROM; STL V12, V10 AMA; 16
EN819; 26; CV88; 500; 1535; SIE, 1543 OSC; FTW V18 STL; 21
‘A12004; 22; B47; 450; 1536 UNC, 1540 SIE, AMA V16 MEM; 17
SE121; 24; B707; 550; 1537 ROM, 1542 TAN, 1546 UNC; CHI Vi2 Vi4 DAL; 18
DC8; 450; 1541 OSC, 1547 ROM; LAX V10 PIT; 20

TR623; 23; B727; 500; 1543 UNC, 1546 TAN; SAT V14 CHI; 21
32441; 25; L188; 400; 1544 ROM, 1550 TAN; CHI Vi2 AMA; 12
BR425; 22; DC8; 450; 1549 OSC, 1554 ROM; PIT V10 SFO; 18
DX826; 26; B707; 550; 1550 SIE, 1555 OSC; DAL V20 V18 STL; 21
MW630; 25; L188; 400; 1555 SIE, 1604 OSC; DAL V18 STL; 17
MX128; 24; B727; 500; 1554 UNC, 1600 SIE; SFO Vi6 CLE; 19
A92900; 21; P2V; 300; 1557 SIE, 1605 UNC; ATL V16 ABQ; 20
EN327; 23; DC7; 350; 1555 TAN; CLE V14 V12 DAL; 14
SE131; 26; CV88; 500; 1600 ROM, 1605 OSC; ABQ V10 ATL; 15
N43201; 22; CRVL; 500; 1603 TAN, 1609 ROM; AMA V12 MKC; 19

Nore: Flightstrip-data order is as follows: flight number; beacon code; type aircraft; airspeed; checkpoint; flight origin, airway(s), and destination; and
altitude,

VT code Time

vTl

VT2

vT3
VT4
VTS
VT6

0010

0030

0050
0220
0300
0310

Appendix A

Tasie A8.

Voice transmission
Message prefiz: “Oklahoma City Center
thisis ...”

Enco Four ten over Sierra at zero zero, one
eight thousand estimate Uncle at zero
five, over.

Pacific nine twenty, was over Romeo on
the hour at one nine thousand, estimating
Oscar at zero five, over.

Midwestern three thirty nine, now on your
frequency.

Transcontinent one forth one,
your frequency, over.

Branner nine fifty, listening your frequency,
over.

Midwestern three thirty nine was over
Oscar at zero three, two zero thousand,
estimating Sierra at one one, over.

listening

19

Aircraft voice transmissions:

VI code
vI7

VT8

vT9

VT10

VTil

VT12

Sample ATC problem.

Time
0420

0440

0500

0550

0610

0810

Voice transmission

Transcontinent one forty one was over
Unele at zero four, twenty one thousand,
estimate Tango at zero eight, over.

Branner nine fifty was over Tango at zero
four, one seven thousand, estimate
Romeo at one zero.

Pacific nine twenty was over Oscar at zero
five, one nine thousand, estimate Bravo
at one five, over.

Enco four ten was over Uncle at zero five,
one eight thousand, estimate Nan at one
two, over

Mexico one sixty six, now listening your
frequency, over.

Transcontinent one forty one was over
Tango at zero eight twenty one thousand,
estimating Romeo at one five, over.



Figure B2. Transfer tree.

others except that it controls the bogey-target and
warning-light events. These latter events do not
have multiple occurrences at the console display,
so they share some of the control function that
Row #1 Control provides in order to reduce
the number of electrical components. All pro-
grammed task events are maintained for approxi-
mately 30 sec at each console, and certain functions
are maintained until other events are completed.
Subfunctions associated with some programmed
events occur at intervals within a 30-sec period.
Timing of the 30-sec periods for event control and
subfunctions is accomplished by six 30-sec timers
(one for each console display panel row) shown
mounted in the lower part of the equipment rack
in Figure B2. The timers are A, W. Haydon
Company, P/N WI 3604, with seven switches that
operate at a predetermined time in accordance
with the 30-sec timer-sequence diagram, Figure

Appendix B

B83, More details of the event-control circuit are
given in the section to follow.

Series of Events. The explanation of a series
of events that can be programmed and their action,
following the block diagram, will be covered to
give an overall understanding of the ATC task
system. The series of events refer to Console #1
and Event Controls, Row #1 Control; however,
the explanation to follow applies to all consoles
(as may be connected to the programmer) and to
the other row controls except in the case of the
bogey-target and warning-light events,

All programmed system action is started after
the tape reader reads the preprogrammed paper
tape. Output from the Tape Reader goes to the
Transfer Tree as described above, and the Trans-
fer Tree outputs go to the Matrix, Projector-Ad-
vance Control, Bogey-Target Control, or Warn-
ing-Light Control. The outputs from the Trans-
fer Tree are the “decoded” inputs at the Tape
Reader, and from here the output creates specific
system actions.

Each time (normally every 10 sec) the Tape
Reader reads a group of codes the projector is
programmed to advance the filmstrip one frame.
Output from the Transfer Tree through the Pro-
jector Advance Control to the Projector causes the
film to advance. The Projector requires a 250-
msec pulse to advance the film. Since the output
pulse at the Transfer Tree is 19 msec long, it must,
be lengthened at the Projector Advance Control
prior to reaching the projector. The Projector
Advance Control is composed of relays including
a G. C. Wilson and Company, Model 591, 0.02- to
5-sec adjustable time delay to lengthen the 19-
msec pulse to 250 msec or greater. The filmstrip
projector used at the console is a DuKane Model
576-47B less base. In order to mount the projector
on the console, the base was removed and parts
housed therein (DC power supply, switches, and
remote-control receptacle) were relocated in a
separate housing.

Provided no other console event is in operation,
the first logical task event to be programmed is
“entry.” The output from the Transfer Tree to
start the entry task consists of two pulses to the
Matrix for selection of the console row and the
entry task. An output from the Matrix causes
a relay in the Entry Task Control to latch up, a
start pulse is furnished to the Counter Start-Stop
Control (starting Counter #1), and an input is
furnished to the Task-Identification Coder. This



VT code Time
VT57 3920
VT58 4040
VT59 4110
VT60 4120
VT61 4140
VT62 4210
VT63 4240
VT64 4300
VT65 4400
VT66 4530
VT67 4610
VT68 4630
VT69 4650
VT70 4710
VT71 4800
Appendix A

Voice transmission

Horizon two twenty two, now on your
frequency, over.

‘Transcontinent six twenty three, on your
frequency, over.

Nan three two four four one, now on your
frequency, over.

Air Force one two zero zero four was over
Sierra at four one, one seven thousand,
éstimate Papa at four eight, over.

Horizon two twenty two, was over Oscar at
four one, twenty thousand, estimate
Romeo at four seven, over.

Enco eight nineteen, was over Oscar at
four two, twenty one thousand, estimate
Echo at five zero, over.

Transcontinent six twenty three passed
over Uncle at four two, twenty one
thousand, estimate Tango four six, over.

Southeastern one twenty one was over
‘Tango at four three, one eight thousand,
estimate Uncle at four seven, over.

Nan three two four four one was over
Romeo at four four, one two thousand,
estimating over Tango at five zero, over.

Branner four twenty five, listening your
frequency, over.

Dixie eight twenty six, on your frequency,
over.

‘Transcontinent six twenty three, was over
‘Tango at four six, twenty one thougand,
estimate Mike at five three, over.

Horizon two twenty two, was over Romeo
at four six, twenty thousand, estimating
Mike at five four.

Southeastern one twenty one, was over
Uncle at four seven, one eight thousand,
estimate Delta at five one, over.

Branner four twenty five, was over Oscar at
four eight, one eight thousand, estimating
Romeo at five four, over.

21

VT code Time
VT72 4910
VT73 5000
VT74 5100
VT75 5300
VT76 5310
VT77 5340
VT78 5410
VT79 5450
VT80 5510
VT81 5530
VT82 5610
VT83 5710
VT84 5800
VT85 5940
VT86 5955

Voice transmission

Dixie eight twenty six, was over Sierra at
four nine, twenty one thousand, estimate
Oscar at five four, over.

Nan three two four four one, was over
Tango at five zero, twelve thousand,
estimating over Nan at five seven.

Enco three twenty seven, listening your
frequency, over.

Mexico one twenty eight, now on your
frequency, over.

Branner four twenty five was over Romeo
at five three, one eight thousand, estimate
Mike at five seven, over.

Air Force nine two nine zero zero, now on
your frequency, over.

Midwestern six thirty, now on your fre-
quency, over.

Dixie eight twenty six, was over Oscar at
five four, twenty one thousand, estimat-
ing Echo at zero one, over.

Mexico one twenty eight was over Uncle at
five five, nineteen thousand, estimate
Sierra at zero zero, over.

Enco three twenty seven, was over Tango
at five five, one four thousand, estimate
Nan at zero three, over.

Midwestern six thirty, was over Sierra at
five six, one seven thousand, estimate
Oscar at zero four, over.

Air Force nine two nine zero zero was over
Sierra at five seven, twenty thousand,
estimating Uncle at zero five, over.

Southeastern one thirty one, now on your
frequency, over.

Mexico one twenty eight, was over Sierra
at five nine, twenty one thousand, esti-
mating Papa at zero seven, over.

Nan four three two zero one now on your
frequency, over.



Event record
(X) Handoff HR883, TR412 course
corrected.

(X) TR412 at wrong altitude (—1,000)

HR113 ovr Oscar
(X) Bogey on
TR412 at correct altitude

Bogey off

(X) EL #2

EN210 ovr Romeo

Enter MW314, V14-V12, 20,000 (FS
#14)

(X) Fail-safe flashes

(X) Handoff A11038

(X) EL #1

Enter V61588, V16, 13,000 (FS #15)
(X) EL #3

BR416, V20-V16, 15,000 (FS #16)
(X) Handoff EN211

HR113 ovr Romeo

(X) EL #5

Enter N81778, V14, 19 (FS #17)
Handoff HR113

MW314 ovr Tango

V61588 ovr Uncle

TR412 ovr Osear

(X) BL #y

Enter PA118, V12-V10, 16,000 (FS #18)

N81778 ovr Uncle
(X) Handoff TR412

(X) Handoff MW314

Appendix A

Voice
transmission

VT #34

VT #35

VT #36

VT #37

VT #38

VT #39

VT #40

VT #41

VT #42
VT #43
VT #44

VT #45

VT #46

16

Time

30

50
3200
10
20
30

50
3300
10
20
30
40
50
3400
10
20
30
40
50
3500
10

20
30
40
50
3500
10
20
30
40
50
3700
10
20
30
40
50

3800
10
20
30
40
50

3900
10
20
30

50
4000
10

30
40
50

Event record
(X) N81778 at wrong altitude (+ 1,000)
PA118 ovr Romeo

BR416 ovr Sierra
(X) BR4I16 wrong turn

N81778 at correct altitude

BR4I6 corrects course

(X) EL #6,

Enter EN819, V18, 21,000 (FS #19)
V61588 ovr Sierra

(X) EL #2

Enter A12004, V16, 17,000 (FS #20)
(X) Handoff PA118

N81778 ovr Tango

EN819 ovr Sierra

(X) Handoff V61588

(X) BL #4

Enter SE121, V12-V14, 18,000 (FS #21)
(X) Handof BR416

A12004 ovr Uncle
(X) Handoff N81778

(X) Bogey on
SE121 over Romeo

Bogey off
(X) EL #1

Enter HR222, V10, 20,000 (FS #22)

(X) Pail-safe flashes

(X) EL #3
Enter TR623, V14, 21,000 (#23)

(X) EL #6

Voice
transmission

VT #47

VT #48

VT #49

VT #50

VT #52

VT #53

‘VT #54

VT #55

VT #56

VT #57

VT #58


1

RESPONSE TM (SECONDS)

eee ee we

Fieure 6. Radar ATC task learning by FSS instructors.

subtask the next hour, etc., (2) tiredness produced
by a full day’s work of teaching in their own lab-
oratory, and (3) the small number of subjects
represented by each point. Note that a few missed.
signals, each involving 80 sec of error, could have
a marked effect on the mean values* plotted.

By Day 3 (Hours 7, 8, 9) subjects are appar-
ently reaching the point of subtask integration
and overall task mastery. Perhaps this state would
have been more evident at an earlier point in time
if testing could have been conducted under more
ideal conditions (ie, daytime) with training dis-
tributed over several days. Achievement of a
stable level of performance by Day 3 is also sug-
gested by the curves of Figure 7, which compare
the response time means of the four monitoring
subtasks other than entries for the two test groups.
This figure also clearly reveals a higher level of
performance by the terminal group as contrasted
with the FSS group. Such a result, if attributed
to the different experience backgrounds of the two

*Because of extreme scores, the median statistic would be a
more appropriate reflection of behavior during the first few hours
of testing; however, the mean was considered to be the better
overall index of task proficiency for the 9-hr period.

RESPONSE TIME (SECONDS)

oye oe vo 2 3

HOUR OF TESTING

Ficus 7. Test-group comparisons: Average of four
monitoring subtasks (altitude and route check, bogey,
warning light).

groups, would appear to validate the design of
the experimental task as one involving radar ATC
task elements, or, put another way, as one requir-
ing human functions or abilities similar to those
needed by radar ATC personnel.

The superiority of the terminal subjects appears
to prevail for all subtasks as seen in Figures 8 to
12. This is surprisingly true even in the case of
the simplest response, that to entries. One point
that perhaps requires explaining is the initial,
poor response to bogey targets evidenced by the
terminal subjects in Figure 12. From posttest
debriefing, this was related to an initial tendency
on their part to ignore all traffic except that under
ATC jurisdiction, a tendency characteristic of
their real-life controller's task.

The final chart, Figure 13, shows the duration
and frequency of voice communications plotted

rs
TERMINAL “<4
i ae oe |
rr
wour oF restIe

RESPONSE TIME (SECONDS)

Frovre 8. Test-group comparisons: Entries (radar ATC
task).


ton switch circuit. If the Handoff pushbutton is
not operated during the 30-sec period, the
Handoff Buzzer will sound during the 10- to 20-sec
period. Operating the Handoff pushbutton dur-
ing the event period causes the buzzer to be dis-
abled and the Handoff light to come on. After
approximately 29.5 sec of the 30-sec handoff pe-
riod, regardless of whether there has been a re-
sponse or not to the event, the Altitude light and
Code light are extinguished by a switch on the
30-sec Timer. Due to the condition of the Hand-
off Task-Control Circuit, the latched relay in the
Handoff Buzzer will sound during the 10- to 20-sec
Timer, causing the Handoff light to go out (if it
is on), and the 30-sec Timer resets to zero time
reference.

The event controls for Row #2 through Row
#6 are identical to Row #1, except that the
bogey-target and warning-light controls are not
repeated. All six console displays are identical,
and additional consoles are connected as noted on
the block diagram.

The sequence of operations described above is
for illustration only. Any timed task (entry, al-
titude check, route check, bogey target and warn-
ing light) can occur separately at any 40-sec in-
terval. Thirty seconds are required for the task
and 10 sec are allowed for the response-time data
to be recorded by the data-acquisition complex.
The full 10 sec are not required for data acquisi-
tion; however, events can be initiated at intervals
of 10 sec only. The handoff event that is untimed
can occur at any 10-sec interval if no other timed
task is occurring on the same row. The bogey-
target and warning-light events are considered to
be on Row #1. The altitude and projector-
advance function can occur at any 10-sec interval.

Data Acquisition. As mentioned, with each
timed event an electronic counter is used to record
the response time. There is one counter for each
ATC console. Five of the counters are Hewlett-
Packard Co., Model 521A R-H68, and one is Model
521A R-H67, the latter being identical to the others
except that it contains a 100-cps oscillator and
output connector. All counter inputs are con-
nected to count the 100-cps signal. The Counter

Appendix B

Start-Stop Control accepts a voltage pulse from
either the Transfer Tree or Matrix, depending on
the event, that starts all counters simultaneously.
When an event response is made at any console
display, a voltage is applied to the Counter Start-
Stop Control that stops its associated counter. If
@ response is made at each console display prior
to the end of the 30-sec period, all counters will
be stopped, and the data-acquisition equipment
records the response times. If, however, one or all
counters are not stopped via a response, the count-
ers are stopped at approximately 29.5 sec by the
30-sec Timer. The automatic stop is available
from all 30-sec Timers and is isolated from the
individual control circuits by diodes as shown in
Figure B1.

The Flexowriter, Dymec Model DY-2540 cou-
pler, and the six electronic counters comprise the
data-acquisition equipment and were purchased as
a system, prewired to work together. The re-
cording format for the Flexowriter is two digits
of time information (input furnished by us), one
digit of identification information (input fur-
nished by us), and four digits of response-time
information from each of six counters. Four
digits of response time provide a measure to the
nearest 0.01 sec when counting the 100-eps signal.
When the Coupler is in the automatic mode of
operation, it samples all inputs after all counters
have stopped counting, converts the inputs to the
Flexowriter code, and causes the Flexowriter to
print out and return the carriage. After the
Flexowriter has printed out the information, all
counters are reset to zero by the Coupler.

Each time one of the timed events is initiated via
the Transfer Tree or Matrix, a voltage signal is
fed to the Task Identification Coder. The coder
contains a relay arrangement that produces and
holds a coded task-identification output that the
Coupler accepts. Task-identification codes sup-
plied to the Flexowriter by the Coupler cause the
Flexowriter to print the number 1 for entry, 2 for
altitude check, 3 for route check, 4 for bogey tar-
get, and 5 for warning light. After the output
from the Task-Identification Coder is scanned, the


Ficure 3. Audio and tape-reader inputs.

marizes the event rate load for one ATC problem;
the subtables do not reflect increases in workload
imposed by programmed deviations from flight
plans. The column at the left of each set of sub-
tables lists the events making up each problem:
(1) Entries refers to the number of new aircraft
scheduled to appear on the radar screen.
Starred-entry frequencies during the first 10 min
of the problem indicate that the frequency includes
aircraft already on the radar screen when the
problem began; this never exceeds two aircraft.
(2) Intersection crossings indicates the number of
times aircraft pass through intersections without
changing airways; the operator must monitor in-
tersections to detect unauthorized route changes
and to ensure that aircraft are following their
flight plan in terms of time and direction. (3)
Airway changes refers to scheduled or planned
airway changes. The ATC operator must watch
intersections to ensure that scheduled airway
changes take place. (4) Voice transmissions re-
fers to the number of voice transmissions the ATC

operator must acknowledge. (5) Handoffs refers
to the number of aircraft whose responsibility the
ATC operator must transfer as they leave his area
of control. The entries in the main body of each
subtable are the number of events of a given: class
occurring during each successive 10-min subperiod
of the problem. The total number of events per
10-min subperiod (within-column) can be taken
as an indicator of amount of operator task load-
ing. Summarized at the bottom of each subtable
are the characteristics of the airway sector the op-
erator must monitor during the problem in terms
of the number of airways and airway intersections.

For those desiring additional insight into the
development of a problem, Appendix A contains
a complete script for a single problem with com-
plete associated flightstrip, voice-transmission, and
airway data.

Appendix B contains details on the electrical-
engineering design and operation characteristics
of the system.



lem to a value different from flight plan, the sub-
ject is required to depress a blue “altitude check”
button next to the indicator. Another subtask re-
quires pressing of a related, yellow “route-check”
button if an aircraft’s track changes to an incor-
rect heading after clearing an intersection. In
both of these later subtasks, detections made with-
in 80 sec are signalled by illumination of the indi-
cator. Deviations are all programmed for self-
correction within 30 sec. The last column con-
tains a red “handoff” button to be depressed within
10 sec of a target’s appearance over a handoff
point. Pressing the button at the correct time il-
Juminates it, and within 30 sec the panel row is
cleared for entry of the next aircraft. Failure to
respond to either an entry or handoff within 10
sec is signalled by a buzzer. A white plastic strip,
next to the beacon-code column, provides the sub-
ject with a space to make grease-pencil notations
as needed.

To the left of the radar screen is a light gun to
be used to “interrogate” bogey aircraft that ap-
pear, unannounced, off an airway. To test the
operator’s attention to peripheral events, a red
“fail-safe” warning light (located at the top of
the console), normally “on,” is periodically pro-
grammed to begin flashing for 30 sec. It is to
be reset by movement of a lever switch immedi-
ately below. The distance from the light to the
exact center of the projected radar display is 22
in.

Tape-recorded voice communications from “pi-
lots” announce over a speaker the aircraft entries
and position reports. A digital clock is available
on the console for reference. Subjects are asked
to acknowledge all transmissions and repeat esti-
mates, using a desk-stand microphone.

A rack to the subject’s right is used for “dead-
wood.” In addition to the lighting produced by
the projector, 2 40-w lamp mounted at the top
right of the console provides illumination of the
flight strips. Intensity of illumination in the test
rooms is somewhat less than that found in
ARTCC’s but greater than that found in IFR
rooms. Typical (average) brightness readings,
taken with a Spectra brightness spot meter, were
as follows: airway reference map on desk, 0.40
ft-1; strips at desk level, 2.32 ft-1; strips in vertical
rack, 8.62 ft-1 (range 0.41 bottom to 11.50 top) ;
white plastic strip, 0.58 ft-1; clock, 4.42 ft-1; alti-
tude readouts, 2.40 ft-1; illuminated beacon code,
169.1 ft-l; radar targets, 3.85 ft-1 (range 1.30 to

6.68); and intersection markings, 0.86 ft-l.
Orange filters are used over the lamp and radar
sereen.

B. Programming and Scoring. Task pro-
gramming is accomplished through relay circuitry
selected by codes punched in paper tape that is
pulsed every 10 sec to advance through a tape
reader (Figure 3). The tape code also controls
the advance of the filmstrip projector. Whenever
a critical event (e.g., altitude deviation) is pro-
grammed to occur at a console, a reference signal
activates electronic counters. A subject’s correct
response stops the counter, which, after all counters
are stopped or after 30 sec, is scanned and reset by
a coupler. The stored values, now in binary-
coded-decimal format, are then released to a
Friden Flexowriter (Figure 1), which types the
time of the event occurrence within the test hour,
a coded event identification, and all subject re-
sponse times in hundredths of a second. The
Flexowriter also punches all data on paper tape
for reference. Figure 4 is a flow diagram illus-
trating the essential programming events.

A bank of counters and timers (Figure 3) cu-
mulates the frequency and duration of subject com-
munications in response to recorded pilot “re-
ports” played from the tape recorder shown.

©. Problem Characteristics. Seven, hour-long,
punched-tape problems were prepared from de-
tailed scripts. On the average, each problem re-
quires the subject to handle 30 aircraft, thereby
entailing 30 responses each to entries and handoffs
(the latter were not timed). Target load never
exceeds six active aircraft (not counting bogey tar-
gets) and is never less than one aircraft at any
one time. Time of entry and direction of flight
are distributed irregularly, with an attempt being
made to avoid a concentration of targets in any
one area of the display. The altitude and route
check, warning light, and bogey subtasks were
each programmed to occur once within every 10-
min block of time, with the time of their occur-
rence within each block being distributed irreg-
ularly.

Table 1 presents summaries of basic operator
workloads, in terms of event rate, which charac-
terize each of the seven problems used in our
studies. These workloads are imposed by the
flight plans and nature of the control sector (ie.,
number of airways and intersections and their
configuration) associated with each problem.
Each of the seven subtables shown in Table 1 sum-


Time
4100
10
20
30
40
50
4200
10
20
30
40
50
4300
10

30
40
50
4400

20
30

50

4500
10
20
30
40
50

4600
10
20
30
40

4700
10
20
30
40
50

4800
10
20
30
40
50

4900
10
20
30
40
50

5000

20
30

Event record
Enter N32441, V12, 12,000 (FS #24)
12004 ovr Sierra
HR222 ovr Osear

EN819 ovr Oscar

TR623 ovr Uncle
SE121 ovr Tango
(X) Handoff A12004
(X) Handoff EN819

N32441 ovr Romeo

(X) Bogey on

Bogey off
(X) EL #2

Enter BR425, V10, 18,000
(X) EL #6

Enter DX826, V20-V18, 21,000
(ES #26)
(X) N32441 at wrong altitude (+ 1,000)
TR623 ovr Tango
HR222 ovr Romeo
$E121 ovr Uncle
(X) SE121 wrong turn
32441 at correct altitude

SE121 corrects course
BR425 ovr Oscar
(X) Fail-safe flashes

(X) Handoff T R623

(X) Handoff SE121

(X) Handoff HR222

(X) EL #3

Appendix A

Voice
transmission

VT #59
VT #60

VT #61
VT #62

VT #63

VT #64

VT #65

VT #66
VT #67
VT #68

VT #70

VT #71

VT #72

VT #73

17

Time
40
50

5100
10
20
30
40
50

5200
10
20
30
40
50

5300

10
20
30
49
50
5400
10
20
30
40
50
5500
10
20
30
40
50
5600
10
20
30
40
50
5700
10
20
30

40
50
5800
10
20
30
40
50
5900
10
20
30
40
50

Event record
Enter MW630, V18, 17,000 (FS #27)

(X) Fail-safe flashes

(X) Handoff N32441

(X) El #4
Enter MX128, V16, 19,000 (FS.#28)

BR425 ovr Romeo
(X) EL#

Enter 492900, V16, 20,000 (FS #29)
(X) EL #5

Enter EN327, V18, 17,000 (FS #29)
(X) 492900 wrong altitude (+2,000)
MX128 ovr Uncle

MW630 ovr Tango

(X) _MW630 wrong turn

492900 at correct altitude

(X) Handoff DX826

MW630 corrects course

EN327 ovr Sierra

(X) Handoff BR425

(X) Bogey on
A92900 ovr Sierra

Boeey off
(X) EL #6

Enter SE131, V10, 15,000 (FS #31)

(X) Handoff MW630

(X) EL #2
MX128 ovr Sierra
Enter N43201, V12, 19,000 (FS #32)

STOP PROBLEM

Voice
transmission

VT #74

VT #75

VT #76
VT #77

VT #78

VT #79

VT #80
VT #81

VT #82

VT #83

VT #84

VT #85



AUDIO
Ce) [aren

TAPE RECORDER

<<

RELAY EVENTS ‘SUBUJECT'S
CIRCUITRY CONSOLE

PROGRAM ;

INPUT

Boag)"
L

SCANNER
COUPLER

Frovre 4, System flow diagram.
III. Experiment I.

The purpose of the initial study was twofold:
(a) to measure and compare the amount of learn-
ing by different types of subjects over 9 hr of prac-
tice; (b) to check equipment and experimental
procedures under prolonged operational condi-
tions.

A. Method. Six instructors from the FAA
Academy volunteered to serve as subjects with the
imowledge they would be paid an hourly overtime
rate for their participation. The three tested the
first week were experienced flight-service person-
nel, familiar with ATC phraseology and flight-
strips, but having no radar-control experience.
The three tested the second week were terminal
ATC controllers with radar experience, but having
no work history in enroute (center) control. Five
of the subjects clustered in age around 30 yr, while
the sixth, an FSS instructor, was in his 50’s.

The FSS group was tested the first week on
Tuesday, Thursday, and Friday evenings; the ter-
minal group was tested on Monday, Tuesday, and
Wednesday evenings of the following week. Sub-
jects reported to the laboratory at 6 p.m. On the
first evening for each group, an initial hour was
devoted to task indoctrination and demonstration
by the experimenter using a practice problem.
Prior to the start of each problem, subjects were
given time to arrange their flightstrips, study their
control-sector airways map, and mark the radar
screen as desired. Three i-hr problems were run
each evening separated by 15-min “breaks.” Six
different problems were involved in the testing,
with those from Day 1 being repeated on Day 3.

211-398 O—66-——2

During the breaks, the experimenter informed
each subject individually of signals missed in the
problem just completed.

B. Results. Figures 5 and 6 show the plots for
the two test groups of the response times averaged
over each hour for each of the five scored subtasks.
The separate curves all show a general decline with
time, reflecting task learning, and indicate the
relative difficulty of the subtasks. The flashing
entry light is certainly the most perceptible stimu-
lus event and provokes a quick response. In-
creased response times appear to follow in the
order (a) warning light, (b) bogey, (c) route
check, and (d) altitude check. It had been pre-
dicted that route check would produce the highest
response times due to the amount of attention and
forethought needed to anticipate a deviation ; how-
ever, subjects presumably were able with training
to learn to monitor traffic effectively at the time
when deviations could be expected. On the other
hand, subjects apparently devoted less attention
to scanning of the auxiliary panel where altitude
deviations were to be detected.

Irregularities apparent in the two figures are
felt to be a function of (1) changes in orientation
toward the task as subjects concentrate on one sub-
task this hour (at the expense of others), a second

RESPONSE TWE GECONDS!

Se BREE

ate

ry a ry
our oF TesrING

Fieure 5. Radar ATC task

instructors.

learning by terminal



APPENDIX Bt

ELECTRICAL-ENGINEERING DESIGN

This appendix is a technical explanation of the
ATC task-system design and operation using a
block diagram, charts, and photographs. The in-
formation presented is intended for technical per-
sonnel with a background in electronics who desire
an overall understanding of the complete system.
No specific details of the electrical circuitry or
construction of the system are given. Refer to
the report text for an explanation of the purpose of
the ATC system and how it is used.

All references to system circuitry pertain to the
block diagram shown in Figure B1.

Programmer and Controls. Operation of the
ATC task is initiated by starting the Pulse Gener-
ator shown in Figure 3, text (fourth panel above
tape reader). The Pulse Generator contains
switches, indicator lamps, and an A. W. Haydon
Company, P/N WI 3601, timer. The timer has
two switches that operate once every 10 sec. One
timer switch produces the 10-sec system master
pulse, which is 40 msec long, and the other switch
is for reset control of the timer.

The output from the Pulse Generator goes to
the Tape Reader Start-Stop control. This control
is a latching relay arrangement, whereby the 40-
msec pulse from the Pulse Generator latches a
relay for start control of the tape reader.

The start control output from the Tape Reader
Start-Stop Control operates the tape-reader mag-
netic clutch, causing the Tape Reader to read the
punched paper tape. The tape reader continues
to read until a stop code is encountered, initiating
a stop pulse that is applied to the Tape-Reader
Start-Stop Control and causing the “start” relay
to unlatch. The tape reader is an eight-level
Friden Model 2, shown in. Figure 3, text, that
operates at 600 RPM (one reading per 100 msec).
The tape for the reader is punched (coded) on the
Friden Flexowriter Model SPD, Figure 1, text,
which is also part of the data-acquisition complex.
The ATC task system requires 37 different code
combinations to accomplish all events. Seven of
the eight tape levels are used for coding pro-
grammed operations, and the eighth level is used
to initiate the stop pulse from the Tape Reader to

*Prepared by Clifton H. Hunter.

23

the Tape Reader Start-Stop Control. Operating
the Flexowriter carriage return is the only way to
register a hole in the eighth level.

Seven outputs and a command pulse from the
Tape Reader are connected to the Transfer Tree.
The seven outputs control the Transfer-Tree re-
lays, which route the command pulse to one of the
36 outputs. The Transfer Tree is wired to corre-
spond to an arbitrarily assigned code. The
sequence of operation is such that the input-to-out-
put path through the Transfer Tree is completed
before the command pulse is applied; the pulse is
removed before the path is interrupted. Applica-
tion of the command pulse is controlled by a switch
operated by a cam fixed to the tape-reader drive
shaft. Thirty-three outputs from the Transfer
Tree go to the Matrix, and one each goes to the
Bogey-Target Control, Warning Light Control,
and Projector Advance Control. Operation of
these three controls will be covered in a later
section.

The Matrix that follows the Transfer Tree con-
sists of 6 rows and 27 columns of relays such that
any row output can be connected to any column
output to form a complete electrical path. The
33 inputs to the Matrix result in 162 (6X27) pos-
sible outputs. The 6 rows are associated with 6
horizontal rows at the console display panel, and
the 27 columns are associated with the following
system operations: 1 for entry, 12 for altitude, 12
for altitude error, 1 for route check, and 1 for hand-
off. To initiate an event at the console through the
Matrix, a row is first selected and the information
stored by the Matrix, using relay circuitry; then
the column is selected. After the column is se-
lected, a pulse approximately 100 msec long is
routed to the Event Control associated with the
selected row and column, and then the Matrix re-
sets to normal. An output from the Matrix also
goes to Task Identification Coder and Counter
Start-Stop Control whenever entry, altitude check,
or route check are programmed. Action of these
outputs will be discussed below.

The 162 outputs from the Matrix connect to the
Event Controls, which consist of five identical cir-
cuits (Row #2 Control through Row #6 Control)
and Row #1 Control, which is similar to the



AM 65-31

DEVELOPMENT AND EVALUATION OF A RADAR
AIR TRAFFIC CONTROL RESEARCH TASK

Richard G. Pearson, Ph. D.
Clifton E. Hunter, B.S.
Gilbert L. Neal, M.A.

Approved by Released by
Mlal Lite PS agel mo
J. Ropert Ditiz, M.D. P. V. Siscet, M.D.
JurEF, Crvrt AEROMEDICAL Frprrau Arr Surgeon

InstiTuTE

December 1965

FEDERAL AVIATION AGENCY

Office of Aviation Medicine



600
4”, SS

at
s00}— w JON ee

DURATION (.01 MINUTES)

FREQUENCY

HOUR OF TESTING

Fieure 13. Voice-transmission data: Group comparisons
(radar ATC task).

for each hour. The frequency plots give the
mean number of times the subjects of the two
groups pressed the microphone talk button. The
theoretical curve is based on a single response to
each incoming pilot report. Apparently subjects
in some instances press the bar more than once to
complete a transmission, This could be taken as
an index of lapsed attention. If so, the FSS sub-
jects are generally more “guilty” in this regard.
Although responding more frequently, the FSS
subjects apparently talk less when they do initiate
a call than do the terminal subjects; this is ap-
parent from the plots for the duration data at the
top of the figure. Put another way, the rates of
duration to frequency suggests that terminal sub-
jects were able to get more into their messages.
This could reflect a greater ability to time-share the
activities involved in their task.

The problems used in testing during Hours 1,
2, and 8 were identical to those used, respectively,
in Hours 7, 8, and 9. The curves of Figure 13
reflect this fact and, in part, provide some support
for the repeatability or test-retest reliability of the
task. At least there is some evidence that the
subjects were responding to instructions. Look-
ing back at Figures 5 through 12, one can also ap-
preciate the performance improvement on these
identical problems that occurs between Day and
Day 3.

IV. Experiment II.

As noted above, the performance curves permit
doubt as to whether a stable baseline of perform-
ance had been achieved in the latter 3 hr of test-
ing. Questions naturally follow as to whether (a)
performance would stabilize earlier as a function
of practice being less concentrated in time, and
(b) additional practice would confirm such sta-
bility, perhaps at a lower level. There also was
an interest in determining how enroute ATC con-
trolers would perform at the task. These con-
siderations formed the basis for the second study.

A. Method. Three instructors from the FAA
Academy volunteered as subjects and were paid
an overly overtime rate. All were experienced
in enroute ATC work. Their ages were 38, 44,
and 45.

Indoctrination and the first hour of testing were
ona Friday. Two-hour sessions, from 5 to 7 p.m.
immediately following the work day, were then
conducted the next week on Monday, Wednesday,
and Friday, and a second week on. Tuesday,
Wednesday, and Thursday, thereby providing a
total of 13 experimental hours. The 2-hr sessions,
it should be noted, were a compromise from desires
to have scheduled daily, single-hour, “distributed-
practice” test sessions. Task procedure was as de-
scribed before, with 15-min intervals between
problems. Seven problems were used in testing,
with those from Hours 1 to 6 being repeated for
Hours 8 to 13.

B. Results. Figure 14 shows the plot of the
response times averaged over each hour for each
of the five scored subtasks, together with the plot
of the response-time means of the four monitoring
subtasks other than entries. The latter curve
would suggest that a stable baseline of perform-
ance is reached by these subjects at Hour 8. Gen-
erally, it appears that, compared to the FSS and
terminal subjects, the enroute group (1) takes
longer to reach baseline, (2) tends to perform
somewhere midway between the two groups
through Hour 7, but (8) thereafter is superior in
performance to both. The greater struggle evi-
denced by the enroute group in reaching baseline
was unanticipated, One conjecture is that habit
interference during early stages of practice pre-
cluded an efficient integration of subtasks. In any
event, it would seem that this study failed to shed
any light on the value of less concentrated prac-
tice. Otherwise, the relative difficulty of the sub-


RESPONSE TIME (SECONDS)

20
|
1]
|
16|
a4
: i |
H 0
g go
: Bou
i * 10
: io ’
/ 8
remus ,|
4
:

, renuwa

5

| ee ee es es ci a a ae

a a a a

nour oF TESTING oun oF Teste

Ficure 9. Test-group comparisons: Altitude checks Ficure 11. Test-group comparisons: Warning light

(radar ATC task). (radar ATC task).
ae A
ae
rN
r YoN
~! \ ap
\
uk \ 2
|
vb
be ‘
y|
nS
ub
15|
ah
gu
nk 3
8 aa
nb g
wh 3
ok 3
Hy
ot .
TeRwinat ty ak /
ok \ c rerun
\
ok
ab \
sh
a DO os
a fe ee oe ee ee ee eee
a
oun oF tesTINe, our oF TESTING

Fieure 10. Test-group comparisons: Route checks (radar Ficure 12. Test-group comparisons: Bogey targets
ATC task). (radar ATC task).



nected at these points (at the console also) with-
out affecting the programmer or other consoles.

IBM wire-contact relays and diode semicon-
ductors are used to accomplish most switching and
control functions. The programmer contains 101,
4-pole, 16, 6-pole, and 70, 12-pole IBM relays and
17 diodes. Each console contains 32, 4-pole and
6, 6-pole IBM relays and 18 diodes. The pro-
grammer and six consoles contain a total of 415
IBM relays and 125 diodes. The wire contact
relay is low in cost, has an operate and release time
of less than 10 msec, and has high reliability.
Current rating for the relay contacts is 35 ma for
200,000,000 operations without contact-are sup-
pression. At 2,000,000 operations, however, the
current rating is 2 amp, which exceeds all but a
few switching requirements for the ATC task
system. The relays are plug-in mounting and
each major circuit function block is contained on
a standard-size 19-in.-wide specially constructed
relay-mounting frame. All circuit function
blocks interconnect at the junction panel located in
the lower portion of the rack shown in Figure B2.
The equipment rack on the right side (Figure 1,
text) is a standard FAA communication-equip-
ment rack, which is 81 in. high and has center panel
mounting and double doors; the other two racks
are standard FAA relay racks, which are 72 in.
high.

All lights and switches located.on the right side
of all consoles, as shown in Figure 2, text, are
manufactured by Micro-Switch except the digital
readouts previously mentioned. All these lights
and switches are installed on an aluminum plate
that can be easily removed. Front panels and re-
lay assemblies, as shown in Figure B4, are inter-
changeable among consoles.

Appendix B

30

Fiavre B4. Console interior.

U.S, GOVERNMENT PRINTING OFFICE:1966 O—211~308


Coupler furnishes a reset pulse to the coder, caus-
ing it to return to normal condition. The Task-
Identification Panel shown above the program
tape reader in Figure 3, text, contains three lamps
labeled 1, 2, and 2’, which indicate to the program
operator the task in operation. Reading of the
lamps is as follows: 1 for number 1, 2 for number
2, 1+2 for number 3, 2+2’ for number 4, and
1+2+2’ for number 5.

The Elapsed-Time Clock Coder is used to pro-
duce two digits of time information for the data-
acquisition complex. The coder contains power
switches, reset switch, indicator lamps, a stepping
switch, and an A. W. Haydon Co., P/N 203, Series
13600, timer. The timer has two switches that
operate once every minute, One switch advances
the stepping switch and the other switch is for
reset control of the timer. Output from the coder
is such that the Coupler accepts the information
and furnishes it to the Flexowriter each time the
coder output is sampled by the Coupler. Time
range for the coder is 0 to 99 min in 1-min in-
tervals.

The Microphone Operation Count and Timing
Panel shown above the tape reader in Figure 3,
text, registers the number of times the microphone
push-to-talk switch located at the console display
is operated and the total accumulated time the
switch is operated. This portion of the ATC task
system is not electrically connected (except for
power supply) to any other part of the system.
The microphones (one is shown in Figure 2, text)
are Turner Model 254C, the counters are Veeder-
Root Series 1506 reset magnet counters, and the
running-time meters are Cramer Type 6338 with
0 to 999.99-min ranges.

Accessory Components. The Magnetic Tape
Recorder and speaker system used with the ATC
system is not electrically connected to the main
system. The tape recorder is a Wollensak Model
T-1980 stereo and mono record/playback unit
with 11 w per channel output. One channel is used
to drive seven 4-in.-diameter speakers. One
speaker is located at each console display and one
at the top of the left-hand program rack as shown

Appendix B

in Figure 1, text. Output impedance of the re-
corder is 8 ohms, and the speaker input impedance
is 8.2 ohms. All speakers are connected in paral-
lel. Although this results in a poor impedance
match, the audio fidelity is better than the con-
dition to be simulated. Output from the recorder
is connected to the system at a jack located above
the program tape reader as shown in Figure 3,
text.

A Talk-a-Phone Model T-C-4912 intercom-
munication system with one master station lo-
cated at the programmer equipment and one sta-
tion located at each display console is used with
the ATC task system. The communication sys-
tem facilitates maintenance, is used for giving in-
doctrinations and instructions, and permits com-
munication between the program operator and sub-
jects in case there are system malfunctions.

Primary power for the ATC task system is 48
vDCand120v AC. All system DC voltages come
from two 48-v power supplies located in the bot-
tom part of the left-hand program rack shown in
Figure 1, text. Meters are associated with each
power supply for monitoring current and volt-
age. One power supply is FAA type FA-5252
rated at 5 amp and the other is a Sola type 281561
rated at 10 amp. One power supply is used to
operate the tape-reader magnetic clutch, elapsed-
time clock coder (because of the stepping switch)
and the transfer tree; this prevents large or fre-
quent voltage transients from affecting lamp cir-
cuits in the console display. All DC power for
each console is supplied by the programmer. AC
power at each console is obtained by individual
connection to the commercial power source. The
only items requiring AC power at the consoles are
the projector, a digital clock, and a desk Jamp.
A panel of six toggle switches enables the operator
to select any one of the six ATC consoles for
operation.

ATC consoles are connected to the programmer
with a 150-wire telephone-type cable. All six 150-
wire cables terminate at the programmer in the
rear bottom of the equipment rack shown in Fig-
ure B2. Any console can be connected or discon-



Table 1. Summary of ATC operator basic work load.

Problem 1 Problem 2
Events 10-min subperiods Total 10-min subperiods: Total
events: events
1 2 3 4 5 6 1 2 3 4 5 6
Entries 6 | 5] 4] 5 4] 28 7m! 5/ 5] 5] 4] 5] 31
Intersection crossings 7/71] 6! 7} 9| 8] 44 7 | 5| 8] 7] 5] 6] 38
Airway changes 2] of} 3} 1 2] 8 1} 3} 1] rf 4] af at
Voice transmissions 15 | 11] 14] 12] 14] 14] 80 13} 13} 14] 13} 14] 12] 79
Handoffs 2) 4] 7] 2] 5] 5) 25 2] 41 6] 6] 3] 5] 26
No. airways: 6 No. intersections: 5 No. airways: 6 No. intersections: 4
Problem 3 Problem 4
Entries TM! 7! 4] 6] 4] 5] 33 s*) 5] 6] 3] 5] 6] 33
Intersection crossings 9 | 8}10) 6} ir] 8| 52 8 12) 7] 8] 9] 8] 52
Airway changes 2] 4} 4] 3] 4] 3] 20 1} of] 3} 1] 1] a] 7
Voice transmissions 16 | 19] 17} 17 | 18 | 16 | 103 15 | 17] 17} 12] 13] 16] 90
Handofis 3 | 6/6! 4} 6| 6| 31 4] 5/ 5] 5] 5| 3] 27
No. airways: 7 No. intersections: 7 No. airways: 6 No. intersections: 6
Problem 5 Problem 6
vents 10-min subperiods Total 10-min subperiods ‘total
events events
1 2 3 4 5 1 2 3 4 5 6
Entries sel 4} 6] 4] 4] 6] 32 s*| 4) 4] 6] 3} 6] 31
Intersection crossings 8 | 9} 6] 7] 9] 6] 45 6 | 8} 9] 7] 7} 10] 47
Airway changes 1} 1] 3] 2] 1} 2] 10 1} o/] 1] 1} 1] of 4
Voice transmissions 15 | 14] 14] 14] 15] 14] 86 14 | 10] 14] 14) 13 | 15 | 80
Handoffs 2/5!) 5] 6] 5] 4| 27 2 | 6] 4] 5] 3] 5] 25
No. airways: 6 No. intersections: 5 No. airways: 5 No. intersections: 5
Problem 7
Entries 8* 4 5 4 6 4 31
Intersection crossings 5 | 6] 6| 6] 7] 4] 34
Airway changes 2] 1} 1] 1} 1} 2] 9
Voice transmissions 12 | 11} 11} 12] 14] 10] 70
Handoffs 2/6] 4} 4] 5] 5] 26
No. airways: 5 No. intersections: 4



VT code Time
VT1i3 0830
VT14 0920
VT15 0950
VT16 = 1030
VT17_ (1100
VTI8 = 1150
VT19 1330
VT20 1350
VT21 1410
VT22 1430
VT23 1530
VT24 1630
VT25 1800
VT26 1820
VT27 1840
VT28 1850
VT29 1910
VT30 2020
VT31 21380
VT32 2130
VT33 2200
VT34 2320

Appendix A

Voice transmission

Mexico one sixty six was over Oscar at
zero eight, one six thousand, estimate
Sierra at one six over.

Branner nine fifty passed Romeo at zero
nine, one seven thousand, estimate
Alpha at one eight, over.

Dixie three seventy five now on your
frequency, over.

Horizon eight eighty two, now on your
frequency, over.

Midwestern three thirty nine passed over
Sierra at one one, two zero thousand,
estimate Whiskey at two zero.

Southeastern one ninety one, listening your
frequency, over.

Dixie three seventy five was over Tango at
one three, one two thousand, estimate
Uncle at one nine, over.

Horizon eight eighty two was over Sierra
at one three, one seven thousand, esti-
mate Osear at two one, over.

Transcontinent one forty one was over

Romeo at one four, two one thousand,
estimating Alpha at two four, over.

Southeast one ninety one was over Uncle
at one four, one five thousand, estimate
Sierra at one seven, over,

Air Force one one zero three eight, now
listening your frequency, over.

Mexico, one sixty six passed Sierra at one
sic, one six thousand, estimate Whiskey
at two five.

Air Force one one zero three eight, was over
Romeo at one eight, one six thousand,
estimate Tango at two five, over.

Southeastern one ninety one, was over
Sierra at one eight, one five thousand,
estimate Papa at two five, over.

Enco two eleven now on your frequency,
over.

Dixie three seventy five was over Uncle at
one eight, one two thousand, estimate
Delta at two four, over.

‘Transcontinent four twelve listening your
frequency, over.

Enco two eleven was over Oscar at two
zero, one eight thousand, estimate Romeo
at two four, over.

Horizon eight eighty two was over Oscar
at two one, one seven thousand, esti-
mating Echo at two nine, over.

Horizon one thirteen listening your fre-
quency, over.

‘Transcontinent four twelve passed Sierra
at two two, one nine thousand, estimate
Oscar at two two, over.

Horizon one thirteen, was over Oscar two
three, at one four thousand, estimate
Romeo at two eight, over.

20

VT code Time

VT35 2400
VT36 2450
VT37 2510
VT38 2630
VT39 2720
VT40 2800
VT41 2840
VT42 2920
VT43 2940
VT44 3000
VT45 3020
VT46 3050

_

VT47 = 3220
VT48 3240
VT49 3350
VT50 3410
VT51 3430
VT52 3500
VT53 3530
VT54 .-.-

VT55 3650
VT56 3810

Voice transmission

Air Force one one zero three eight, was
over Tango at two four, one six thou-
sand, estimate Nan at three one, over.

Enco two eleven, was over Romeo at two
four, one eight thousand, estimate Mike
at three one, over.

Midwestern three fourteen, now on your
frequency, over.

Navy six one five eight eight, listening your
frequency, over.

Branner four sixteen, now on your fre-
quency, over.

Horizon one thirteen was over Romeo at
two eight, one four thousand, estimating
Alpha, at three seven, over.

Nan eight one seven seven eight, listening
your frequency, over.

Midwestern three fourteen, was over Tango
at two nine, twenty thousand, estimate
Nan at three seven, over.

Navy six one five eight eight, was over
Unele at two nine, one three thousand,
estimate Sierra at three four, over.

Transcontinent four twelve was over Oscar
at two nine, one nine thousand, estimate
Echo at three six, over.

Pacifie one eighteen, now listening your
frequency, over.

Nan eight one seven seven eight was over
Unele at three zero, one nine thousand,
estimate Tango at three four.

Pacific one eighteen was over Romeo at
three two, one six thousand, estimate
Mike at four zero, over.

Branner four sixteen, was over Sierra at
three two, one five thousand, estimating
Papa at four one, over.

Enco eight nineteen, now on your fre-
quency, over.

Navy six one five cight eight, was over
Sierra at three four, one three thousand,
estimate Papa at four three, over.

Air Force one two zero zero four, now on
your frequency, over.

Nan eight one seven seven cight was over
Tango at three four, one nine thousand,
estimate Mike at four one, over.

Enco eight nineteen was over Sierra at
three five, two one thousand, estimate
Oscar at four two.

Southeastern one twenty one, listening your
frequency, over.

Air Force one two zero zero four, was over
Uncle at three six, one seven thousand,
estimate Sierra at four one, over.

Southeastern one twenty one, was over
Romeo at three eight, eighteen thousand,
estimate Tango at four two, over.


seconos
° rp a %
entay auzzer
nbote SEER oF
te ewirenes)
enray FLasven Off
rigR_ oon
CONTROL. Beye
leas
TimeR “ore output OFF FL
COUNTER 30 SEC, STOP org
a Gabe Cie on GorTRoL. OF
WHEN ENTRY TASK TS OW AW 08
Auronavic nanpore Luss
WHET Mange ore
Sethe fon OE
FEDERAL AVIATION AGENCY
nstALnATION ano uate DEPOT
30—SECOND TIMER
SEQUENCE lara
fe: Bare ace [oe wr [osrea-s-aaj IMD-B-406

Fievre B3. Timer-sequence diagram.

latter input is further coded so that identification
information is furnished to the data-acquisition
complex (discussed in the following section). An
output from the Entry Task Control starts the 30-
sec Timer, which was resting at zero time refer-
ence. Another output from the Entry Task
Control applies voltage through the 30-sec Timer
to the Entry Flasher located in Console #1,
causing the Entry illuminated-type pushbutton
light to flash on and off. Provided the Entry push-
button switch is not operated, the light will con-
tinue to flash for 20 sec, then stop flashing and
remain on; meanwhile, 10 sec after the entry light
has commenced flashing, the Entry Buzzer will
have begun sounding for 10 sec. The flasher and
buzzer subfunctions are controlled by switches on
the 30-sec Timer, as shown by the timing diagram,
Figure 33. At approximately 29.5 sec in the 30-
sec period, the 30-sec Timer operates the Code
light on through the Code Light Control, unlatches
the relay in the Entry Task Control, and pulses
the Counter Start-Stop Control, stopping the
counter for Console #1. Release of the relay in

Appendix B

the Entry Task Control causes the Entry Light
to go off, and the 30-sec Timer motor-control
switch (Figure 20) takes control of the timer and
stops it at zero time reference. A latching relay
in the Code Light Control causes the Code light
to remain on, Operating the Entry pushbutton
during the 30-sec interval causes the Code light to
come on and remain on due to the Code Light Con-
trol, causes Counter #1 to stop, causes the Entry
Flasher and Entry Buzzer to be inactivated
(whether operating or not), and finally causes the
Entry light to remain on until the end of the 30-
sec period.

An altitude associated with the entry is normally
programmed next to appear on the face of the Row
#1 digital readout. The digital readouts are In-
dustrial Electronic Engineer Series No. 10,000,
which display numbers 11 through 22. The output
from the Transfer Tree that causes an altitude to
be displayed at Console #1 consists of two pulses
to the Matrix for selection of the console row and
the altitude number. Output from the Matrix
illuminates an Altitude light at Console #1

26


II. The Radar ATC Task System.

A. Task Description. The experimental situa-
tion developed utilizes six task consoles located in
separate rooms, plus a programming and data-
processing complex (Figure 1) located in a sepa-
rate control room. The subject’s console, shown
in Figure 2, is designed to simulate certain cur-
rent and future developmental aspects of a con-

Frevre 1,

Programming

troller’s task in a semiautomatic enroute ATC
center. Slanted at 70°, the radar display shows
airways, checkpoints, intersections, and aircraft
targets within the subject’s control sector. An air-
ways map immediately below the display is avail-
able for reference. Up to six radar targets are
presented at one time by 35-mm filmstrips, made
up from an animated display.

and data-processing complex.


APPENDIX A*

SAMPLE ATO PROBLEM

This section describes the script and associated
material that form the basis for the ATC task
research problem. Included are: (1) a represent-
ative ATC event script (Table A1) listing in time
sequence (a) all events to which the ATC subject
must attend, (b) those events to which he must
respond, and (c) those events that are témed and
scored; (2) a listing (Table A2) of all flight-
strip data by entry order and flight number; (3)
a listing (Table A3) of all voice transmissions
from aircraft that the ATC subject receives; (4)

TO
N aeuh
a

MIKE

Fieure Al,

*Prepared by Gilbert L, Neal.

13

an airway diagram (Figure Al) for the problem ;
and (5) representative flight strips (Figure A2)
that have been used with the problem.

Table Al is arranged in three columns: Time,
Event Record, and Voice Transmissions. The
time column shows that each problem begins at
0000 min and ends at the end of 5950 min. It also
shows that events are updated every 10sec. Inthe
Event Record column opposite each 10-sec segment
are listed the events occurring therein. Events
preceded by an (X) indicate an event to which

10
ECHO

vis 47

To
WHISKEY.

Airway configuration.



Time
0300
10
20
30
40
50
0400

10
20
30
40
50
0500
10
20
30
40
50
0600
10
20
30
40
50
0700
10
20
30
40
50
0800
10
20
30
40
50
0900
10
20
30
40
50
1000
10

20
30
40
50
1100
10
20
30
40
50
1200
10
20
30

Event record

(X) MW339 Altitude error (+ 2,000 ft)

TR141 ovr Uncle
MW339 at correct altitude
(X) Fail-safe warning

BR950 ovr Tango

EN410 ovr Victor
(X) EL #6

Enter MX166, V18, 16,000 (FS #6)

(X) Handoff PA920

(X) Handoff EN410

TRI141 ovr Tango

(X) TR141 Fails to turn

MX166 ovr Oscar

TRI1A41 corrects course

BR950 ovr Romeo

(X) BL #2

Enter DX375, V14, 12,000 (FS #7)
(X) EL #1

Enter HR882, V20-V18, 17,000 (FS #8)
Handoff BR950

‘MW339 ovr Sierra

(X) EL #4

Enter SE191, V16, 15,000 (FS #9)
(X) Handoff MW339

Appendix A

Voice
transmission
VI #5
VT #6

VT #7
VT #8

VT #9

VT #10

VT #11

VT #12

VT #14

VT #15

VT #16

VT #17

VT #18

15

Time
40

1300
10
20
30

40

1400
10
20
30

50
1500
10
20
30

50
1600
10
20
30
40
50
1700
10
20
30
40

1800
10
20
30
40
50

1900
10
20
30
40
50

2000
10
20
30
40
50

2100

10
20
30
40
50
2200

Event record

(X) Bogey on

DX875 ovr Tango
Bogey off

HR882 ovr Sierra
TRI141 ovr Romeo

(X) TRIAL incorrect turn

TRI141 corrects course

(X) EL #8

Enter A11038, V12, 16,000 (FS #10)

(X) Handoff TR141
MX166 ovr Sierra

(X) Fail-safe warning

(X) Handoff MX166

(X) EL #6

A11038 ovr Romeo

SE191 ovr Sierra

Enter EN211, V10, 18,000 (FS #11)
DX375 ovr Uncle

(X) EL #6

Enter TR412, V20-V18, 19,000

(X) HR882 Wrong altitude (+1,000)
(X) Handoff SE191

HR882 at correct altitude

(X) Handoff DX375
EN211 ovr Oscar

(X) EL #4

R882 ovr Oscar

Enter HR113, V10-V12, 14,000 (FS
#13)

TR412 ovr Sierra
(X) TR412 wrong turn

Voice
transmission

VT #19

VT #20
‘VT #21

VT #22

VT #23

VT #24

VT #25

VT #26

VT #27
VT #28

VT #29

VT #30

VT #31

VT #33



DEVELOPMENT AND EVALUATION OF A RADAR AIR TRAFFIC
CONTROL RESEARCH TASK

I. Introduction.

This report describes a synthetic radar air traf-
fic control task for laboratory, human-factors
research and the results from initial pilot experi-
mentation, The conditions under which air traf-
fic controllers work, involving workload, time
pressure, and responsibilities for lives and prop-
erty, demand a better understanding of factors
that could degrade performance. Need for the
research tool as described herein arises from spe-
cific conditions that have appeared at times to
compromise efficient operator performance and
that would not feasibly be evaluated outside the
laboratory. Initially, for example, there was a
question of the secondary effects of commonly
used drugs on controller proficiency. Like most
people, controllers resort to over-the-counter and
prescription medicaments in their desire to alle-
viate symptoms or to combat an ailment. Many
drugs, however, especially the ataractics and anti-
histaminics, have a depressant side action and con-
sequently possess the potential for disrupting
skilled behavioral responses. In another area of
concern, Psychology Laboratory research has un-
covered a suggestion of differences among air traf-
fic control (ATC) facilities where behavioral data
were related to shift- and task-rotation schedules.
Hence, it seems reasonable to pursue a program of
definitive ‘study relating work task schedules to
operator efficiency.

When attention was first drawn to the need for
human-factors research on ATC operator-per-
formance variables, the Air Traffic Service made
available certain radar-simulator equipment.
Such simulators, traditionally used in training, re-
quire one or more human programmers to operate
controls that determine the appearance and move-
ment of targets on a CRT display. Initial ob-
servation of the equipment made apparent a crit-
cal objection to its acceptance for research use.
To compare a given subject’s performance from
one day to another and to arrive at any conclu-
sions regarding the variables under study requires
wsurance that the data reflect the subject’s, and

not the experimenter’s, proficiency. It was de-
termined that programmer’s control settings could
vary not only within a given day, but also from
day to day, in terms of both accuracy and latency ;
ie., when a dial was set. Hence, the reliability of
the simulator as a research tool was seen to be lim-
ited by the system that programs it; ie. the
human. A further objection was that the simu-
lator’s mechanical function failed to provide con-
sistent agreement between control settings and tar-
get location and movement on a day-to-day basis.

The alternative was to eliminate the human pro-
grammer. An automated system could function
with high reliability by feeding programmed sig-
nals into a radar display and recording subject
responses to the target patterns. By connecting
several displays in parallel, concurrent testing of
subjects in groups could be realized. Thus, on a
given day, an experimenter could test several sub-
jects on different levels of an independent variable
while having knowledge of environmental and
task control. Such capability affords the experi-
menter greater freedom of experimental design.
The approach further requires only a single tech-
nician to monitor system performance and change
task programs.

With acceptance of the above rationale, engi-
neering design and development of the system de-
scribed below was undertaken with the collabora-
tion of the Installation and Materiel Depot of the
FAA Aeronautical Center. The requirements
originally set forth called for a system that would
ensure repeated presentation of realistic target
patterns and of other synchronized visual and au-
ditory stimuli and that would provide suitable in-
strumentation for measuring and processing sub-
jects’ motor and verbal responses. The system
was to enable the experimenter to evaluate a num-
ber of human functions, to include vigilance in
the detection of critical targets, monitoring of the
course and altitude of enroute traffic, reaction time
both to centrally located and to peripherally lo-
cated visual warning signals, and identification of
potential conflictions.



“WBISEIP Yoord weyssg ‘Tq aunorg

$0b-0-OWI| — Laat | ==

WGLSAS ¥SVL OLY UvOVE

‘Toda TaRIaLWA ONY NOUVTIVISNT
‘AONaDv NOUIAY Twusaad

Terr

92 eee

[ppocoo
O00

[Zon]

STOUINOO LN3AS. ve ronan wauiees 9 HI,

24

Appendix B


ACKNOWLEDGMENTS

The development of the task system and associated audio-visual materials
required the support and interest of a number of people whose contributions
the authors wish to acknowledge.

Within CARI, Harlie W. Huffman contributed significantly to our early
design thinking in the area of electronics. Eugene H. Barker was instrumental
in developing the still-photography technique for filming the animated radar
targets.

From the FAA Academy, John H. Lanius and William J. Berkley were
particularly helpful in our planning. We were also fortunate and grateful
to obtain the full-time services of Bernard Fonza and Duard Leslie for several
months. These two men demonstrated considerable insight and originality in
developing the scripts for all the 1-hr task programs, in filming the animated
radar targets, in developing the airways map and flight-strip materials, and in
tape-recording the voice communications. Perry Bolyard provided admin-
istrative support in behalf of our need for volunteer subjects for the
experiments.

Qualified requestors may obtain Aviation Medical Reports from Defense Documentation
Center. The general public may purchase from Clearinghouse for Federal Scientific and
Technical Information, U.S. Dept. of Commerce, Springfield, Va., 22151.


through the Altitude Readout Interlock. Now,
Row #1 Code light and the programmed Altitude
light are on.

When “altitude check” is programmed, the out-
puts from the Transfer Tree to the Matrix consist
of pulses to select the row, as before, and a new or
incorrect altitude number, as the case may be.
There are two outputs from the Matrix to the Row
#1 Control, a start pulse to the Counter Start-
Stop Control and an input to the Task-Identifica-
tion Coder. Action of the Counter Start-Stop
Control and Task Identification Coder are the
same as in the case of the entry task. One pulse
input to the Row #1 Control goes to the Altitude-
Check Task Control, latching a relay that starts
the 30-sec Timer formerly resting at zero time
reference. The same pulse activates the Altitude-
Check illuminated-type pushbutton on the console
display so that, if it is operated during the 30-sec
period, that light will come on. At the same time
that the Altitude-Check pushbutton is activated,
the new “error” altitude appears at the Altitude
readout due to the output from the Matrix to the
Altitude Readout Interlock. The old displayed
altitude is extinguished immediately before the
new altitude appears by an electrically interlocked
relay circuit in the Altitude Readout Interlock.
If the Altitude-Check pushbutton is not operated,
at approximately 29.5 sec of the 30-sec period,
the 30-sec Timer causes Counter #1 to stop
and unlatches the relay in the Altitude-Check
Task Control, thereby resetting the 30-sec Timer
to zero time reference. Operating the Altitude-
Check pushbutton during the 30-sec period causes
the Altitude-Check light to come on and Counter
#1 to stop. The Altitude-Check light is extin-
guished at the end of the 30-sec period by the un-
latching of the relay in the Altitude-Check Task
Control.

The “error” altitude displayed by the Altitude
readout remains the same until it is programmed
to change back to the correct altitude. This is
accomplished as it was following the entry task,
except that the error altitude is extinguished
before the correct altitude reappears.

Operation of the “route-check” task proceeds in
a fashion similar to that of the altitude-check
task. For operation of the bogey-target and
warning-light tasks, the Matrix is not required
since these tasks are displayed in only one location
at the console display.

A programmed bogey-target task causes the out-

Appendix B

put from the Transfer Tree to latch a relay in the
Bogey Task Control that starts the 30-sec Timer,
activates the bogey-target response circuit, and
furnishes a start pulse to the Counter Start-Stop
Control and an input to the Task-Identification
Coder. Action of the Counter Start-Stop Con-
trol and Task-Identification Coder is the same as
described above. With no response to the bogey
target, the 30-sec Timer (after approximately
29.5 sec of the 30-sec period) stops Counter #1,
unlatches the relay in the Bogey Task Control,
and advances itself to zero time reference. A re-
sponse to the bogey-target task (removing the
Bogey Light shown in Figure 2, text, from the
holder) operates a snap-action switch located in
the holder, stopping Counter #1. A light in the
barrel of the Bogey Light can be turned on by a
trigger-operated switch at any time during the
task period. The function of the light is to simu-
late an actual radar interrogator gun. The bogey-
light gun is made from an automobile time-light
housing manufactured by Rite Autotronics Corp.

When the “warning-light” task is programmed,
the output from the Transfer Tree causes a relay
to latch-up in the Warning-Light Task Control,
which starts the 30-sec Timer, starts the Warning
Light (which is normally on) to flashing, and fur-
nishes a start pulse to Counter #1 and an input
to the Task-Identification Coder as in the case of
the bogey-target task. The Warning Light is
located near the upper left-hand corner of the con-
sole shown in Figure 2, text. With no response
to the Warning Light, the 30-sec Timer (after
approximately 29.5 sec of the 30-sec period) stops
Counter #1 and unlatches the warning-light task-
control relay, thereby causing the Warning Light
to stop flashing and remain on (normal condition)
and the 30-sec Timer to reset to zero time refer-
ence. Operating the Lever Switch located below
the Warning Light during the task period causes
the Warning Light to stop flashing and remain on
and stops Counter #1.

The last event to be programmed is “handoff,”
and at this time the Code light and an Altitude
light are normally on. Programming handoff
causes outputs from the Transfer Tree to the
Matrix to select the console row and handoff event.
Since response to this event is not timed, there is
no input to the Counter Start-Stop Control or
Task-Identification Coder. Outputs from the
Handoff Task Control start the 30-sec Timer and
activate the Handoff illuminated-type pushbut-



RESPONSE TIME (SECONDS)

ROUTE CHECK
i
/

/
a

MONITORING SUBTASKS

HOUR OF TESTING

Fieve 14. ATC task learning by enroute instructors.

tasks, as indicated by the separate curves of Figure
14, appears comparable to the earlier results. The
voice-transmission data, Figure 15, reveal that
duration and frequency of voice transmissions for
the enroute group are lower in contrast to the
FSS and terminal subjects. This could be a re-
flection of succinct, yet more complete, communi-
cations.

V. Discussion.

From the results of initial testing and subject
critiques, the task and its programs seem fully
suited to the purposes for which they were de-
signed. Because of the number of skills the task
requires and because of the relative ease with
which a number of subjects can be tested, the task
should warrant consideration in any exploratory
test programs related to improved controller selec-
tion, screening, or proficiency appraisal. ‘There
was no attempt in this initial study to look at the
relationship between age and performance, but a
study of age-related functions should provide
some further understanding of the growing body
of evidence that air traffic control is a “young
man’s game.”

DURATION

¢
\
s
/
¢
\
&

FREQUENCY
s

a a a a |
HOUR OF TESTING

Fiaure 15. Voice-transmission data: Enroute instructors
radar ATC task.

One feature of the experimental task that
should be of interest to training personnel is that,
from the outset of testing, the subject is forced to
begin learning a large number of task functions,
or subtasks, in an attempt to stay ahead. The
concept of whole-task learning here, of course, is
quite different from the initial, part-task learning



EN410 or SIE] 180 | MEM view AMA

LISS} UNC}
2 eo id

PA920 01 JROM! 190 | ABQ VIOE CLE

22 Bates ‘8 |

MW339 02 Josc] 200 | sTL vies FTW

loca] si€| ys
23 J450] 1511 [

04 unc]

TRI4I TAN 210 | DAL vIaN vi2N MKC
Scr 1s

28 1505} 0M [

TRADITIONAL FORMAT

EN410 | i501 sie wem | 18

1506 unc | vi6

AMA
21

Lise
400

PA920| iso1 rom | ABO 19
180s osc | vio

2 CLE

8727
500

MW339) i502 osc | ste | 20
ist sie | vie

23 FTW
ce
450 sas
T
RI41 | iso4 unc | var | 2!
1507 TAN | via
2s 1514 ROM | viz
mKe
8707 saa

550

EXPERIMENTAL FORMAT

Ficure A2. Flightstrip formats.

the ATC subject must make a prescribed overt
response, such as pressing a button to acknowledge
the entry of a new aircraft on the radar screen.
Underlined “X-ed” events are timed and scored.
All events must be observed and evaluated since
each subject must decide whether a response is
required. The abbreviation “EL” means that an
entry light flashes; the number with it refers to
the location of the entry light. The abbreviation
“FS” and a number refer to flightstrips listed in
Table A2, where full flight-plan information on
an aircraft is given. The Voice Transmission
column of Table A1 lists the code for each trans-
mission (VT) scheduled to be presented to the
subject; complete content of all voice transmis-
sions is given in Table A3.

It should be noted that airline designations in
Table A2 are fictitious; ie, EN... Enco; DX...
Dixie; MW ... Midwestern; TR . . . Transconti-
nent; MX... Mexico; BR... Branner; HR
... Horizon; SE... Southeastern; and PA
... Pacific. “A”, “V”, and “N” stand for
Airforce, Navy, and nonairline VFR flights,
respectively.

Appendix A

14

Tasrw Al. Event script: Sample ATC problem.

Time

0000
10
20
30
40

0100
10
20
30
40

50

0200
10

20
30

40

50

Voice
Boent record transmission
Air Traffic Status at 0000:
EN 410, V16, ovr Sierra, 18,000 (FS #1)
PA 920, V10 ovr Romeo, 19,000 (FS
#2)
Start Problem
(X) EL #8 VT #1

Enter MW339, V18, 20,000 (FS #3) VT #

VT #3
(X) Bogey on
Bogey off
(X) BL #5
Enter TR141, V14, 21,000 (FS #4)
(X) EL #4 VTE:

Enter BR950, V12, 17,000 (FS #5)
M W339 ovr Oscar