Controllers were asked to indicate the minimum
amount of information needed on a revised strip.
Most frequent responses were: route (15), aircraft
type (12), altitude information (12), call sign (8),
speed (4), and destination (3). Three controllers indi-
cated that they would prefer the strip left unchanged.

The final question pertaining to strips, in general,
asked what information would need to be included on
the PVD data block in order to eliminate the need for
strips. Only one controller said that the strips could
not be eliminated. The most frequent response for
information to add to the data block was destination
(15). Other frequent responses included route (5),
aircraft type (5), heading information (5), requested.
altitude (3), a mark to indicate a flight on anything
other than its filed route (2). One controller suggested
the addition of beacon codes.

Finally, the experimenter asked the controllers to
explain markings, if any, recorded on the notepad.
Four controllers did not record anything on the
notepad. Most frequent responses included: heading
(11), speed (8), location of turbulence (5), callsign
(4), hand-off sector code (3), Charlotte arrival (2),
circle to indicate that information had been passed to
pilot (2), miles in trail (2).

DISCUSSION

Complete removal of the strip information and its
accompanying strip marking responsibilities resulted
in controllers compensating by retrieving informa-
tion from the computer. Despite the need to punch in
FPRs, controllers nevertheless spent more time view-
ing the PVD. Thus, requiring controllers to access
flight data when needed via the FPR allows more time
to watch the PVD than does providing strips and
requiring strip marking. In addition, the presence or_
absence of strips had no effect on either perf nce
or perceived workload. Apparently, the compensatory
behaviors were sufficient to maintain effective control at
what controllers perceived to be acomparable workload.

Flight Progress Strips

The one impact of using the FPR instead of the

strips was in the delay to grant requests. Although * |

grant-time can be viewed as a secondary workload
measure, this seems unlikely since controllers in both
‘conditions did eventually grant the same number of
requests. A more likely explanation is that when
unexpected requests were made of the controller,
retrieving the information via the FPR was slower
than glancing at the strip. Furthermore, since the
scenarios were only 25 minutes in length, controllers
may not have had the opportunity to formulate strat-
egies about how to work without strips, possibly
contributing to the delay.

The written section of the PEQ revealed that con-
trollers found the strips more useful than the notepad,
and that they believed that more information was
available when using strips. Less information was
available in the No Strip condition, and it had to be
accessed in a different manner than in the Strip
condition. In the No Strip condition, only one flight
plan could be inspected at a time. By contrast, when
strips were used, information on aif aircraft in the
sector, and some still outside the sector, was readily
available for the controller's use in the strip bay. It
may be advantageous to keep the strips, but eliminate
the requirement of strip marking. This is similar to the
Restricted condition of Vortac, Edwards, Fuller, and
Manning (1993), which yielded some superior cogni-
tive measures.

Vortac, Edwards, Fuller, and Manning (1993) ac-
tually found faster and more frequent granting of
requests in the Restricted condition. At first glance,
this may appear to conflict with the current results,
butin fact, the studies were quite different. In Vortac,
Edwards, Fuller, and Manning (1993) the requests
required controllers to wait before the request could
be granted, thus allowing a prospective memory com-
ponent, In addition, subjects in Vortac, Edwards,
Fuller, and Manning (1993) had access to strips, but
were not allowed to mark or manipulate them.

+ Simulations were performed before destination information was added to the data block.

il


Flight Progress Strips

The way in which automation of the strips is to be
carried out has caused a significant amount of debate
(e.g., Hopkin, 1988; Vortac, 1993). Any automated
system that replaces the strips by an electronic display
may qualitatively change the controller’s interaction
with flight data (Vortac & Gettys, 1990). The con-
cern has been expressed that automation of a task that
the controller currently performs manually may be
detrimental if the cognitive impact of that automa-
tion is not considered (Hopkin, 1988).

Cognitive psychology has long known that memory
is better for something you do yourself than it is for
something done for you (Slamecka & Graf, 1978). It
follows that the activities of sequencing, marking on,
and moving the strips into and out of the active bay
may provide improved incidental memory for rel-
evant information. Hopkin (1988) stated that auto-
mation that decreases or eliminates the cognitively
beneficial interaction with strips may have a negative
impact on controller performance. Hopkin (1988;
1989; 1991) has argued that removal of strips, and the
consequent elimination of their incidental memory
role, may adversely affect controller performance. For
instance, if a controller offsets or marks on “a particu-
lar flight strip within the flight strip board as a
memory aid...the fact that the action was under the
controller’s initiative helped the controller remember
why it had been taken and what had to be remem-
bered.” (Hopkin, 1989, p. 1639). Under automation,
some of these operations will most likely be performed
by computer.

However, given the complexity of the ATC system,
the behaviors used to compensate for loss of strips
may, overall, yield advantages over those available
under current conditions. Currently, controllers are
required to maintain a written record of control
actions taken with the aircraft. Removing manual
strip board management tasks may increase the time
controllers have available to scan the PVD. The elimi-
nation of strip marking would likely free up cognitive
resources to deal with other aspects of controlling
traffic. In fact, informal reports of controllers suggest
that strip marking becomes secondary to PVD separa-
tion under high traffic density and workload. From
this view, a decrease in workload afforded by the
automation of tasks which are secondary to the

controller's job (i.e., sequencing and updating strips),
will be beneficial (Vortac, Edwards, Fuller, & Man-
ning, 1993). Thus, an alternative is that the automa-
tion of strips, and the decrease in workload resulting
from removal of the written record-keeping component
of the FPS, will be beneficial to controller performance.

Previous studies suggested that workload would be
reduced if strips are available, but strip marking and
board management are eliminated. Vortac, Edwards,
Fuller, and Manning (1993) manipulated the avail-
ability of strips to Academy instructors. In one condi-
tion, controllers used strips as they normally would
(Normal). In the other condition (Restricted), con-
trollers were provided with limited strips, which dis-
played callsign, aircraft type, assigned altitude, and
route, but controllers were not allowed to re-sequence,
write on, or otherwise interact with the strips. The
Restricted condition served as an automation analog
more severe than any proposed automation, in terms
of lost functionality. Controllers in the Restricted
condition performed as well as controllers in the
Normal condition on a variety of cognitive measures,
including attentional engagement, visual search, re-
call of flights, and recall of flight data.

Differences that were observed between the two
conditions tended to favor the Restricted condition.
Remembering to grant requests to planes that were
not yet in the controlled airspace was superior when
strip marking was eliminated. Thus, memory to per-
form a task at some time in the future — prospective
memory (Einstein & McDaniel, 1990; Meacham &
Leiman, 1982)— was aided by eliminating strip mark-
ing: Controllers in the Restricted condition granted
more requests, and granted them sooner, than did
those in the Normal condition. Similarly, restricted-
condition controllers were also better at anticipating
future actions. Prospective activities were generally
superior in the Restricted condition, relative to the
Normal condition. These results suggest that the
decrease in workload afforded by the elimination of
updating the strips may, in fact, have beneficial re-
sults.

The results of Vortac, Edwards, Fuller, and Man-
ning (1993) make one wonder if complete removal of
the strips is viable. This would, in large part, depend
on whether the information is presented elsewhere


oe

OY

Flight Progress Strips

Table 1. Means (standard deviations) for controller behaviors by condition.

Variable Measured (units) No Strip Strip

Time watching PVD (sec.) 1137.80 (84.39) 854.45 (76.86)
Flight plan readout (n) 22.40 (3.66) 5.80 (4.38)
Route display (n) 1.45 (2.19) 1.15 (1.60)
J-rings (n) 2.85 (2.06) 2.65 (1.53)
Conflict Alerts (n) 1.40 (.99) 1.30 (1.17)
Time to grant requests (sec.) 34.87 (20.06) 24.01 (15.81)
Requests unable (n) 0.35 (.58) 0.30 (.73)
Requests ignored (n) 0.35 (.67) 0.70 (1.03)
Total requests to pilot (n) 2.25 (1.02) 1.75 (1.45)
Total requests to center (n) 3.90 (2.59) 3.05 (1.7)

Note: Those effects in bold are significant.

Table 2. Mean number (standard deviations) and type

of remaining actions by condition.

Action No Strip Strip

Route changes 0.70 (0.92) 0.65 (0.67)

Altitude changes 2.15 (1.35) 2.80 (1.40)

Speed changes 0.10 (0.31) 0.05 (0.22)

Accept hand-off 0.05 (0.22) 0.05 (0.22)

Initiate hand-off 5.65 (1.79) 6.00 (1.45)

Switch frequency 7.55 (1.90) 8.25 (1.90)

Other 0.80 (0.95) 1,05 (1.00) }
Total (n) 17.00 (5.64) 18.85 (4.66



Flight Progress Strips

Both scenarios represented the Pulaski sector of
Atlanta Center, which isa high altitude sector respon-
sible for traffic from flight level 240 (24,000 feet
above sea level) to flight level 290. A map of Pulaski
and adjacent sectors can be seen in Figure 2. Geo-
graphically, it covers portions of Virginia, Tennessee,
and North Carolina. Controllers characterize Pulaski
as a busy sector that handles numerous Atlanta arriv-
als, and coordinates traffic with Houston Center.

Procedure

Each controller participated in the Strip condition
and the No Strip condition. The order of scenarios
and the assignment of condition to scenarios were
counterbalanced. The order in which scenarios were
presented occurred equally often, and each condition
was assigned equally often to each scenario across
subjects.

In the Strip condition, controllers were told to
control traffic as they normally would. In the No Strip
condition, controllers were told that no strips were
available, but that they would be given a notepad to
write down any needed information. Controllers were
also reminded that all other flight control actions
should be performed as they would be in the field.

Before beginning the first scenario, the participant
completed a biographical questionnaire and consent
form. Controllers were then given instructions ex-
plaining that the general purpose of the experiment
was to study the possible consequences of automation
on ATC specialist performance. Next, the subject
matter expert briefed the controller on DYSIM spe-
cific sector information, such as sector codes for
hand-off and miles in trail to adjacent sectors. In
addition, the controller was told how to simulate land
line coordination with other sectors.

Figure 2. Map of Pulaski and its relationship to other en route centers.


(e.g., on the PVD) or whether the information is
removed completely. The reduction in workload pro-
duced by eliminating the strip marking may be suffi-
cient to compensate for the loss of information
provided by the flight strips. When necessary, con-
trollers could retrieve needed information in more
cumbersome ways, but the added effort in these cases
may be insignificant when compared to the workload
reduction that is produced by eliminating board man-
agement responsibilities.

Until now, our research has been limited to the use
of Federal Aviation Administration (FAA) Academy
instructors controlling the fictitious academic Aero
Center airspace. It is important, therefore, to test our
hypotheses using field controllers working familiar
airspace. Active field controllers rarely participate in
empirical studies, making it important to generalize
exploratory findings to the controller workforce.

Thus, the purpose of the current study was to use
field controllers to provide preliminary data on the
actions controllers would take if strips were no longer
available. Some of these actions will be compensatory,
whereas others could suggest likely controller activi-
ties if board management responsibilities were elimi-
nated, In addition, the study examines whether removal
of strip information, and its accompanying board
management responsibilities, results in either deficits
in performance or increases in perceived workload.
Finally, we asked controllers about the use of strips in
controlling traffic.

Controllers participated in two conditions. In the
Strip condition, controllers controlled simulated en
route traffic as they normally would in the field. In the
No Strip condition, controllers controlled traffic with-
out strips, but were given a notepad. This experiment
differs from previous studies (e.g., Vortac, Edwards,
Fuller, & Manning, 1993) in that the current study
denied controllers any access to strips whatsoever. All
other control actions were performed the same as they
would be with live traffic. In particular, access to the
QAK (Quick Action Keyboard) was not limited, per-
mitting controllers to compensate for removal of the
strips by obtaining whatever information they needed
from the CRD (Computerized Readout Display).
Thus, unlike previous work, complete removal of the
strips not only relieves the controller of strip marking

Flight Progress Strips

and board management responsibilities, as was the
case in Vortac, Edwards, Fuller, and Manning (1993),
but also denies the controller easy access to some flight
plan data. If easy access to the eliminated flight plan
data is necessary, we would expect compensatory
behavior, but whether or not workload and performance
are affected depends on the tradeoff between elimi-
nating strip marking and eliminating strip information.

METHOD

Participants

Twenty air traffic controllers at the FAA Atlanta
Air Route Traffic Control Center (hereafter referred
to as Atlanta Center) volunteered as participants.
Range of time employed by the FAA was from 3 years
10 months to 34 years 6 months. All controllers,
except one, were full performance level (FPL). The
range of time employed at Atlanta Center as an air
traffic controller was from 8 months to 34 years 6
months. All participants were from the same area of
specialization.

Simulation Apparatus and Scenarios

Experimentation used the dynamic simulator
(DYSIM) at the Atlanta Center, which provided a
high-fidelity simulation of air traffic. The PVD con-
sole was to the controller’s left; the strip bay to the
controller’s right. Two experimenters and the subject
matter expert directly observed controller activity. A
third experimenter, positioned at the other side of the
room, monitored air traffic communication via a
headset. Three FAA training experts operated the
scenario from “remote” positions. Remotes simulated
pilot communication and activity, as well as adjacent
sector communication and coordination.

Two scenarios were created and judged by a subject
matter expert to be approximately equivalent in com-
plexity and good simulations of live traffic. Scenario
A consisted of 4 departures, 10 arrivals, and 9 over-
flights; scenario B had 9 departures, 4 arrivals, and 9
over-flights. Requests were also built into the sce-
narios. For example, a pilot may ask for a lower or
higher altitude due to turbulence, or ask for a change
in route, such as obtaining a direct route to a destina-
tion. There were 9 pilot requests in each scenario.

|

bse retin Weve

_


Flight Progress Strips

instructed to place an “X” on the line adjacent to the
factor to indicate a response. The controller then took
a 10 min. break, before the next scenario.

Controller Feedback: Post Experimental
Questionnaire

At the conclusion of the experiment, a Post Experi-
mental Questionnaire (PEQ) was administered that
collected controller ratings regarding a variety of
topics, using both written and oral responses (See
Appendix A). The first section of the PEQ contained
three questions per condition pertaining to the utility,
ease of use, and how well they liked each condition.
Question 1 asked how useful the strip/notepad was.
Question 2 referred to how well the controller liked
the strips/notepad. The third question asked the con-
troller to rate the amount of information available
about the aircraft. Controllers made their response to
these questions by placing a mark corresponding to
their rating on a 5 inch horizontal line below each
question. The second section was conducted by inter-
view and audio taped. Questions in this section were
designed to determine if there were perceived differ-
ences between real air traffic control and the simula-
tions. Further, this section was designed to collect
controllers’ observations about the use of strips, both
during the experiment and in general.

RESULTS AND DISCUSSION

Measurements were grouped into on-line and post-
scenario measures for analysis. All data were analyzed
by comparing the Strip and No Strip conditions. All
tests used a significance level of & = .05.

Controller Behaviors

The first set of measurements consisted of the
following: total time watching PVD, number of FPRs,
number of route displays, number of J-rings used,
number of conflict alerts activated, mean time to
grant pilot requests, number of “unable” requests,
number of requests ignored, number of controller-to-
pilot requests, number of controller-to-center requests,
and total actions remaining to complete at the end of
the scenario. An omnibus multivariate analysis of
variance (MANOVA) revealed a significant differ-

ence between conditions [F(10,29)=23.76]. A repeated
measures analysis of variance (ANOVA) was therefore
computed for all measures independently. Table 1
shows the means (standard deviations) for controller
behavior measures.

Although each of the 10 actions occurred more
often or took longer in the No Strip, compared with
Strip condition, only three yielded significant
univariate F statistics. When controllers were in the
No Strip condition they spent significantly more time
watching the PVD [A(1,19)=380.63], made a greater
number of FPRs (A(1,19)=259.96] and took signifi-
cantly longer to grant pilot requests [A(1,19)=4.81]
than they did when they were in the Strip condition.

Finally, even though controllers were given a
notepad to use in any way they wished, they recorded
very little information. The sparse amount of note-
taking may have been due to the inconvenience of
having to record the callsign (AID) or CID, along
with other needed information. On the present strips,
AID and CID are already provided, so that the con-
troller has this information at hand.

Controller actions differed between conditions to
compensate for the lack of strips. Controllers in the
No Strip condition had to change the way in which
they accessed flight information. To compensate for
the absence of strip information, controllers used the
FPR function to get information normally printed on
a strip. An increase in keyboard activity could have
been detrimental, but it was arguably a reasonable
trade-off relative to the time normally needed to scan
the strip bay.

Although controllers entered more keystrokes, the
amount of time controllers watched the PVD during
the 25 min. scenario significantly increased from
14.24 minutes in the Strip condition, to 18.98 min-
utes in the No Strip condition. Allowing controllers
to watch the PVD for a significantly longer period of
time could result in a better representation, or “men-
tal picture” of the dynamic and complex situation in
which they were engaged (Vortac, 1993). Itisinterest-
ing to note that several controllers remarked that they
felt as though they were unable to spend as much time
watching the PVD in the No Strip condition, when in
fact, just the opposite was true.





Table 3. OUT rating frequencies Strip /No Strip condition.

Job Function Job Function Satisfactory Needs Unsatisfactory
Category Improvement
Separation Separation is ensured 19/19 0/0 1A
Safety alerts are provided 19/19 0” 0/0
Control Judgment | Awareness is maintained 15/15 28 3/2
Good control judgment is applied 16/18 2A 2A
Control actions are correctly planned 20/19 0/0 on
Positive control is provided 20/19 oA 0/0
Methods & Prompt action to correct errors is taken AWNT 1/0 0/0
Procedures
Effective traffic flow is maintained 178 3h 0/0
Aircraft identity is maintained 157 5/3 0/0
Strip posting is complete/correct N/A N/A N/A
Clearance delivery is complete/correct/timely 210 on 0/0
LOA’s/Directives are adhered to 18/16 1A on
Provides general control information 19/18 Ww 0/0
Rapidly recovers form equipment failures and NA N/A N/A
emergencies
Visual scanning is accomplished 18/18 2/2 0/0
Effective working speed is maintained 20/20 0/0 0/0
Traffic advisories are provided 20/19 0/0 0/0
Equipment Equipment status information is maintained 5/5 0/0 0/0
Computer entries are complete/correct 19/16 on 0/0
Equipment capabilities utilized/understood 18/19 0/0 0/0
Communication’ | Required coordinations are performed 5/6 10/7 517
Coordination
Cooperative, professional manner is maintained 20/20 0/0 0/0
Communication is clear and concise 179 2n 1/0
Uses prescribed phraseology 19/17 13 0/0
Makes only necessary transmissions 20/20 0/0 0/0
Uses appropriate communications method 18/19 2A 0/0
Relief briefings are complete and accurate N/A N/A NIA



Flight Progress Strips

Performance

Table 2 shows the mean number of actions remain-
ing for the controller to take at the end of each
scenario. No significant differences were found be-
tween the two conditions for remaining actions
[FU,19)=1.11]. Overall, controllers in the Strip con-
dition (M=18.85) had slightly more actions remain-
ing at the conclusion of the scenario than did the
controllers without strips (M=17.00).

There were three possible responses for each item
on the OJT evaluation form. These were “satisfac-
tory.” “needs improvement.” or “unsatisfactory.” A
2 analysis revealed no significant differences in OJT
ratings across conditions. Table 3 shows the OJT
rating frequencies by condition.

Perceived Workload

Perceived workload/performance ratings were coded
by measuring, in centimeters, the distance from the
left anchor (low side of the scale) to the center of the
“X” marked by the controller on the modified NASA
TLX. A MANOVA on all dimensions of workload
revealed no significant differences between condi-
tions (see Table 4). Thus, the controllers’ perceived
workload was not increased by the lack of strips.

Notwithstanding the direct indicators of controller
re-adjustment to strip removal, neither performance
nor perceived workload (as we measured them in this
study) was affected when the strips were removed.
Despite the lack of differences between conditions in
performance and perceived workload, controllers in
the No Strip condition took significantly longer to
grant pilot requests than they did in the Strip condi-
tion.

Why this occurred is not entirely clear. Although
perceived workload (as measured by the modified
NASA TLX) was not affected, time to grant pilot
requests for the previous analysis could be viewed as a
secondary measure of workload. Alternatively, the
difference may have been simply due to the amount of
information readily available to the controller. In the
No Strip condition, controllers may have had to do
more flight plan readouts for relevant information
before granting a request, thereby slowing time to
grant it. We will return to how to interpret grant-time
in the Discussion.

Controller Feedback: Written Responses

More qualitative information was provided by the
Post Experimental Questionnaire. The PEQ scales
were scored by measuring distance from the right
anchor to the mark placed by the controller on a
horizontal line (in centimeters). Means for these rat-
ings are shown in Table 5. Individual repeated measures
ANOVAs on all rating questions revealed a significant
advantage for the strips for “usefulness” [A(1,19)=5.40]
and “amount of information” [A(1,19)=8.77].

In order to determine how realistic the scenarios
were, we asked controllers if they controlled traffic
any differently than they did in the field. Thirteen
responded that there was not a difference. Of the
seven indicating a qualitative difference, the reasons
given were that they were more relaxed (3), and that
there was no one marking the strip for them (no D-
side) (2). Likewise, of the seven controllers who indi-
cated that there was something unusual about the
scenarios, the most frequent responses were the lack of
a D-side (4) and that the strips were taken away (2).
Finally, when controllers were asked which of the
scenarios they preferred, responses never pertained to
the scenarios themselves (i.e. flight patterns, level of
difficulty, etc.). Rather, responses dealt with whether
or not the strips were present. Nine controllers indi-
cated that they preferred using strips. The most com-
mon reasons given were: information was readily
available (3), strips are more comfortable to use (3),
and strips were available to write on (2). The remain-
ing 11 indicated a preference for using the notepad.
The most common reasons were that the strips are cumber-

some (5), and that they had more time to view the PVD (2).

Controller Feedback: Oral Responses

When asked how the lack of strips impaired perfor-
mance, nine controllers indicated that they experi-
enced no impairment. Other responses: information
was not readily available (3), more mental load (2),
could not pre-plan (2), had to do more flight plan
readouts (2), and were not used to absence of strips (2).

Controllers indicated that strips were especially
useful for: communication purposes (5), heading in-
formation (5), pre-planning (4), speed information
(3), route information (3), transitioning aircraft (2),
and sequencing aircraft (2).


Each scenario was started by the remote operator,
and recording of time began when the strip printer
began printing strips. Strips were printed in the No
Strip condition, even though they were not distrib-
uted to the controller.

Controller Behavior

During each scenario, one experimenter, using a
hand-held stopwatch, recorded the total amount of
time the controller watched the PVD. A second ex-
perimenter observed the controller and recorded four
measures. Two of these were obtained from the
controller’s use of the QAK: The experimenter re-
corded the number of times the controller called up a
flight plan readout (EPR) and the number of times a
route was displayed. The FPR function displays the
complete flight plan ofan aircraft on the CRD (asmall
screen next to the PVD). A route display draws a line
representing an aircraft's assigned route on the PVD.

The remaining measures were obtained from the
PVD. First, the total number of “J-rings” activated by
the controller was recorded. “J-rings” are 12 sided
polygons (this is a facility software adaptation and
varies between facilities) 5 nautical miles in diameter
(the size of the “J-ring” also varies from facility to
facility), that the controller can place around selected
aircraft on the PVD. J-Rings are used to help the
controller check separation between aircraft.

The other measure involved recording the number
of Conflict Alerts that occurred during the scenario. A
Conflict Alert is a software feature that causes the data
blocks of two or more aircraft to flash when the
computer projects that they will lose standard separa-
tion in 3 min. Conflict Alerts can be activated for
many reasons and are not restricted to aircraft that are
at the same altitude or, in fact, to aircraft that will
eventually lose separation. In addition to flashing data
blocks for the conflicting pair, a Conflict Alert mes-
sage is displayed at the top of | the PVD to indicate the
flight’s computer identification number (CID) and
controlling sector.

‘All voice communications were recorded on audio
tape. In addition, specific communications measures
were recorded by the third experimenter. All requests
made to the controller by pilots (pilot requests) were

Flight Progress Strips

recorded, as was the time taken for the controller to
granta pilot’s request. Requests that were not granted
were counted and classified as either “unable” (con-
troller denied the request) or “ignore” (no action was
taken regarding the request).

Two forms of controller requests were also re-
corded: the number of times controllers requested
information from the pilot (such as speed or current
heading), and the number of requests of other centers.
For example, the controller may request control of
planes about to enter the sector, in order to coordinate
flight patterns within the airspace. Such requests can
be used by controllers to compensate for information
not easily available elsewhere.

Performance Ratings

The scenario was stopped after 25 min. The con-
troller was removed from the simulation while the
subject-matter expert completed two measures. First,
each aircraft still in the airspace was checked for any
remaining actions needed to move the plane com-
pletely through the sector. For example, a plane leav-
ing the sector may need to be handed-off to the next
sector. Given the same set of initial conditions and the
same elapsed time, a controller working with a more
efficient system should have fewer remaining actions
to perform than when working with a less efficient
system (Vortac, Edwards, Fuller, Manning, 1993).
Second, the subject-matter expert completed FAA
Form 3120-25(6-90) hereafter referred to as an OjT
form, which consists of 27 points of evaluation per-
taining to controller performance.

Perceived Workload

In the meantime, the controller completed a modi-
fied workload/ performance measure adapted from the
NASA Task Load Index (TLX). For a complete de-
scription of the TLX, see Hart and Straveland (1988).
The factors measured were mental demand, physical
demand, temporal demand, effort, frustration, and
performance. The form listed all factors with a 9.6
centimeter horizontal line next to each. The line was
marked “low” on the left end and “high” on the right
end. In addition, a vertical mark in the center of the
line signified the halfway mark, The controllers were



HOW CONTROLLERS COMPENSATE FORTHE LACK
OF FLIGHT PROGRESS STRIPS

INTRODUCTION

Over the next few years, the human-computer
interface in en route air traffic control (ATC) is
expected to change considerably. Increasing air traffic
has placed more and more demands upon the ATC
system. Controllers currently handle seven million
flights a year with a system that was designed in the
1960s (Stix, 1994). The combination of these anti-
quated computer displays and the projected increase
in air traffic over the next few years underscores the
need for updating the ATC system now in use.

Currently, en route control of high altitude flights
between airports depends on two primary tools: the
computer-augmented radar information available on
the Plan View Display (PVD) and the flight informa-
tion available on the Flight Progress Strip. An example
representation of an aircraft on the PVD can be seen
in the upper panel of Figure 1; its flight information
on the Flight Progress Strip can be seen in the lower
panel. Thirty-one fields for information are printed
on the strips and contain such information as call
sign, planned route, filed airspeed, assigned altitude,
time of arrival, etc. This information supplements the

altitude, position, and speed data available from the
PVD. While an aircraft is in the controller’s sector,
the controller writes on the corresponding strip to
reflect the control instructions, any changes made in
the flight plan, and other contacts with the aircraft.

Although the specific changes brought about by
long term automation remain uncertain at this time,
it is likely that the automation will considerably
change the manner in which flight data will be dis-
played and manipulated. The automation will most
likely combine, in some way, the information cur-
rently available on the strips and the information
presented on the PVD.

Understanding the way in which controllers com-
pensate for changes in the strips is necessary if we are
to determine the amount of information they need to
efficiently perform their job without compromising
aviation safety. In particular, automation displays
may be limited in the amount of flight information
that can be displayed, making it important to under-
stand the potential hazards of removing information
currently available on the strips.

DAL310 PpeMw
BI37/A

a [te

003 01 PSK pdbis

PSK CVI 3653/7612 2311

210

Figure 1. An aircraft's representation on the PVD and on a Flight Progress Strip.

1


Flight Progress Strips

SUMMARY

present study, no significant differences in controller
perceived workload or in performance were found
relative to the Strip condition. The lack of strips did
force controllers to find information in other ways,
and this did slow the time to grant pilot requests.
Controllers compensated for the lack of strips by
making more Flight Plan Readouts, but having no
strip marking responsibilities allowed them to spend
more time watching the PVD. Overall, we conclude
that the decrease in workload afforded by the removal
of strip marking appears to outweigh the detrimental _
effects of changing or removing strips. (Additional
research is necessary to determine if there are more
substantial long term effects to strip removal). Be-
cause removal of strips apparently allows controllers
more time to watch the PVD, additional research
should be done to determine which information should
be added to the PVD data block.

Controllers identified what information on the
strips they viewed as most important. Information
that controllers deemed vital could be placed in the
data block by means of an information time sharing
arrangement. The placement of more information on
the data block, and less on the strip, should result in
more time to view the PVD, thereby allowing control-
lers to concentrate on the primary task of aircraft
separation. a

Finally, additional studies should be conducted
with field controllers responsible for other types of
sectors (e.g., low altitude arrival, or non-radar) to
determine when, or if, controllers can compensate as
successfully as they were able to in the current inves-
tigation. In any case, the current work shows that, at
least for sectors like Alanta Center’s Pulaski, such com-
pensation is possible without commensurate increases in _
workload or substantial decreases in perform:

Despite the extreme No Strip condition, in _

12

REFERENCES

Einstein, G. O., & McDaniel, M. A. (1990). Normal
aging and prospective memory. Journal of Experi-
mental Psychology: Learning, Memory, and Cogni-
tion, 16, 717-726.

Hart, S. G., & Staveland, L. E. (1988). Development of
NASA-TLX (Task Load Index): Results of empiri-
cal and theoretical research. In: P. A. Hancock and
N. Meshkati (Eds), Human Mental Workload(pp.
139-183). Amsterdam, North-Holland.

Hopkin, V. D. (1988). Human factors aspects of the
AERA 2 program. Farnborough, U. K.: Royal Air
Force Institute of Aviation Medicine.

Hopkin, V. D. (1989). Man-machine interface prob-
lems in designing air traffic control systems. Pro-
ceedings of the IEEE, 77, 1634-1642.

Hopkin V. D. (1991). The impact of automation on air
traffic control systems. In J. A. Wise, V.D. Hopkin
& M. L. Smith (Eds.). Automation and systems
issues in air traffic control. (pp. 3-19). Springer-
Verlag: Berlin.

Meacham, J. A., & Leiman, B. (1982). Remembering to
perform future actions. In U. Neisser (Ed.), Memory
observed: Remembering in natural context (pp. 327-
336). San Francisco: Freeman.

Slamecka, N. J., & Graf, P. (1978). The generation
effect: Delineation of a phenomenon. Journal of

Experimental Psychology: Human Learning and
Memory, 4, 592-604.

Stix, G. (1994). Aging airways. Scientific American,
May, 270, 96-104.

Vortac, O. U. (1993). Should HAL open the pod bay
doors? An argument for modular automation. In
D. J. Garland & J. A. Wise (Eds.), Human factors
and advanced aviation technologies (pp. 159-163).
Daytona Beach, FL: Embry-Riddle Aeronautical
University Press.

Vortac, O. U., & Gettys, C. F. (1990). Cognitive factors
in the use of flight progress strips: Implications for
automation. Cognitive Processes Laboratory, Uni-
versity of Oklahoma, Norman, OK.

Vortac, O. U., Edwards, M. B., Fuller, D. K., & Man-
ning, C. A. (1993). Automation and cognition in
air traffic control: An empirical investigation. Ap-
plied Cognitive Psychology, 7, 631-651.


APPENDIX B

Post Experimental Questionnaire

Questions rated by the controller:

£7)

2)

The scenario with paper strips:

a) How easy to use were the paper strips?

b) How useful were the paper strips?

c) Did you like to use the paper strips?

d) Rate the quality of information you had about the aircraft when using the strips and PVD?

The notepad scenario:

a) How useful was the notepad?

b) Did you like to use the notepad?

c) Rate the quality of information you had about the aircraft when using the notepad and
PVD?

Questions asked by the experimenter:

y)

2)
3)

4)
5)

6)
7)

8)

2)

Excluding the idiosyncrasies of the DYSIM: Did you control traffic any differently than you
normally do on the floor?

Was there anything unusual about the scenarios?

Which of the two scenarios did you like best?

a) Why did you like this scenario?

What did you like about the notepad (or not using the strips)?

In what way, if any, did you feel the lack of available strips may have impaired your perfor-
mance on the problem?

What kind of information did you record on the notepad?

What information do you feel would be essential to include on an FDE (Flight Data Entry—
the electronic equivalent of a flight strip) for a sector like Pulaski (high altitude arrivals)?

In what circumstances did you feel that you really needed to have strips? (For example, before
you accepted hand-off, advance planning about actions to take with aircraft, resolving poten-
tial conflicts)

What information would need to be included on the data block in order to eliminate the need
for strips?

Bl

‘WUS. GOVERNMENT PRINTING OFFICE: 1996 - 760-082/20053


ACKNOWLEDGMENTS

O. U. Vortac represents the collaborative efforts of Francis T. Durso, Scott
D. Gronlund, and Stephan Lewandowsky. Address correspondence to:
Francis T. Durso, Department of Psychology at the University of Oklahoma,
Norman, OK 73019-0535, USA (e-mail: fdurso@uoknor.edu).

Chris Albright can now be contacted at the FAA Civil Aeromedical Institute,
AAM-510, P.O. Box 25082, Oklahoma City, OK 73125, USA (e-mail:
Chris_Albright@mmacmail.jccbi.gov).

We wish to thank the following people:

John Walton and Terry Cox, for their efforts to coordinate our research with
the facility employees before and during our visit;

Cheryl Roberts (our subject matter expert), for her help in the development
of the experiment, as well as her evaluations;

Chris Crawford, for the scenarios he developed for us and the last-minute
changes to the scenarios, as well as his service as a remote pilot;

Mitch Coleman, for his efforts atrecruiting volunteers and his service as A-side;
Patrick Weyand, for recruiting volunteers;

All of our ghost pilots and our volunteers.

This research was supported by Federal Aviation Administration Contract
#DTFA-02-91-C-91089 to the members of O.U. Vortac.

iii


Technical Report Documentation Page

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No.
DOT/FAA/AM-96/5
“4, Title and Subtitle 5. Report Date
How Controllers Compensate for the Lack of Flight Progress Strips February 1996
©. Performing Organkation Code
7. Author(s) 8. Performing Organization Report No.
Chris A. Albright, Todd R. Truitt, Ami B. Barile, O.U. Vortac, and
Carol A. Manning
9. Performing Organization Name and Address 10. Work Unit No. (TRAIS)
FAA Civil Aeromedical Institute
PO Box 25082
Oklahoma City, OK 73125 11. Contract or Grant No.

DTFA-02-91-C-91089
University of Oklahoma Dept. of Psychology
755 W. Lindsey, Room 705

Norman, OK 73019-0535

12. Sponsoring Agency name and Address 13. Type of Report and Period Covered
FAA Office of Aviation Medicine
Federal Aviation Administration
800 Independence Avenue, S.W.
Washington, DC 20591

14. Sponsoring Agency Code

FAA Research and Development Service
Federal Aviation Administration

800 Independence Avenue, S.W.
Washington, DC 20591

15, Supplemental Notes
This work was performed under task AAM-B-94-HRR-141 and Contract No. DTFA-02-91-C-91089.

16. Abstract

The role of the Flight Progress Strip, currently used to display important flight data, has been debated because of
long range plans to automate the air traffic control (ATC) human-computer interface. Currently, the Fight Progress
Strip is viewed by many as an indispensable tool needed for the safe and expeditious separation of air traffic. Long
term plans to automate the American system have initiated a debate on the impact of modifying, or even removing,
the Flight Progress Strip. We looked at the viability of a stripless environment by using the Atlanta Center dynamic
simulator to compare standard ATC operation with an experimental condition that removed the strips completely.
Performance and perceived workload did not differ between conditions. Controllers compensated for the lack of
strips by requesting more flight plan readouts. Without strips controllers took significantly longer to grant requests,
and spent significantly more time looking at the plan view display.

17. Key Words 18. Distribution Statement
Air Traffic Controllers, Automation, Cognitive Document is available to the public through the National
Psychology, Applied Psychology, Flight Progress Strips, | Technical Information Service, Springfield, Virginia
Flight Progress Data 22161
19. Security Classif. (of this report) | 20. Security Classif. (of this page) 21. No, of Pages 22. Price

Unclassified Unclassified 20

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized

i



Flight Progress Strips

Table 4. TLX Mean ratings (standard deviations)

in centimeters by condition

Factor Rated No Strip Strip

Mental demand 6.41 (1.76) 6.77 (1.70)
Physical demand 5.38 (2.58) 6.23 (2.26)
Temporal demand 5.90 (2.00) 6.31 (1.95)
Effort 6.15 (1.85) 6.58 (1.91)
Frustration 4.71 (2.14) 4.41 (2.66)
Performance 6.04 (1.76) 5.84 (1.57)

Note: The higher the score, the higher the perceived workload,
4.8=moderate, 9.6=high.

Table 5. PEQ mean ratings (standard deviations) for

questions by condition
Question No Strip Strip
Usefulness 3.85 (3.79) 6.86 (2.91)
Likeability 4.71 (3.63) 6.53 (3.70)
Amount of information 7.56 (3.91) 10.48 (1.85)

Note: The higher the score, the higher the rating.

10


APPENDIX A
TLX Instructions and TLX

‘We are interested in finding out your perception of how difficult the task is and how well you perform on
the task. Our objective is to measure your perceived “workload” level. The concept of workload is com-
posed of several different factors. Therefore, we would like you to tell us about several individual factors
rather than one overall workload score.

Here is an example of the rating scales. As you can see, there are six scales on which you will
be asked to provide a rating score: mental demand, physical demand, temporal demand, fort, frustra-
tion, and performance.

Rating Scales
Mental demand refers to the level of mental activity like thinking, deciding, and looking that was
required by the task. You will rate this scale from low to high.

Physical demand involves the amount of physical activity required of you, such as controlling or
activating.

Temporal demand tefers to the time pressure you experienced during the task. In other words,
was the pace slow and leisurely or rapid and frantic? If the pace was rapid and frantic you are
experiencing high temporal demand.

Effort refers to how hard you worked (both mentally and physically) in order to achieve your
level of performance.

Frustration \evel refers to how secure and relaxed versus stressed and discouraged you felt
during the task. If you feel secure and relaxed, you have low frustration.

Performance level refers to your perception of your own performance level. Your rating here
should reflect your satisfaction with your performance in accomplishing the goals of the task.

Making your response
You should indicate your rating by placing an ‘X’ on the line adjacent to the item.

For example, if you want to give a high rating of stress factor, place an ‘X’ to the tight of the
half-way mark. The higher the stress rating, the closer the ‘X’ should be “HIGH”. In contrast, if
your stress rating is low, you would place an ‘X’ on the closer toward the “LOW” end of the
line. Likewise, if the stress rating is average place an ‘X’ in the center of the line.

Please give your responses thoughtful consideration, but do not spend too much time deliberating over them. Your
first response will probably accurately reflect your feelings and experiences.

Al