values are lower than the baseline values, pre-
sumably because activity (work) represents re-
lief from some unknown off-the-job stressor.
With the product index, these difficulties are
avoided.

Figures 7, 8, and 9 show in graphic form and
Table 9 shows in tabular form the relationship
between baseline and work values at the facilities
studied. It is clear from these presentations
that the baselines for ne and st at the various
facilities differ significantly. It is also clear that
the responses to work, as represented by st, e,
and ne, vary significantly among the different
facilities, an indication that the controllers not
only start from different stress baselines but rise
to different stress levels during work. Thus, one
must take into consideration the interaction be-
tween baseline and work values if the total stress
exhibited by an individual is to be estimated.
It is important to estimate total stress, for off-
duty stresses undoubtedly are carried over into
the work period and work stress is just as cer-
tainly taken home with the controller from the
job.

17 KETOGENIC STEROIDS

1300- 41300
ert
1200} 41200
tax
. 1100 panera tancray 1100
jaseline Work
1000 ax 71000
‘OAK
900+ 4 900
goo + 800
sane
7ooF 4 700
600+ -| 600
me oTw
1
Soop “4 4 500
400F +400
ow.
300! 300

\¢—— 8 Hours 1

Ficure 7. Relationship between baseline (night sleep
specimen) and response (8-hour pooled work speci-
men) at the various facilities. Ordinate is yg 17-
ketogenic steroids per 100 mg of creatinine. See
‘Table 9 for numerical data.

10

EPINEPHRINE

2.0- 42.0
OFF
mia
ono

Baseline =~ |] Work

tanera
rw
tan croH
vax

Lob 10

‘ono
° °
+———8 Hours ——>1

Fiaure 8, See legend for Figure 7. Ordinate is ps
epinephrine per 100 mg of creatinine.

NOREPINEPHRINE

5.0r np 75.0
ua
mt
4.0 ux 44.0
Boseline ono Work
are
tamer
sor wert 3.0
nero
ma
enn
2.0b rw 12.0
- Ce
rw
Lor 410
° °

'+——-8 Hours

Figure 9. See legend for Figure 7. Ordinate is pg
norepinephrine per 100 mg of creatinine.


COMPARISON OF OPA LOCKA TOWER WITH OTHER ATC FACILITIES
BY MEANS OF A BIOCHEMICAL STRESS INDEX

I. Introduction.

Opa Locka Airport (OPF), located in a close-
in suburb of Miami, Florida, is predominantly
a general aviation airport served by an air traffic
control tower that is in operation 16 hours per
day (0700-2300). Until recently, OPF had an
annual traffic count exceeding 600,000 and was
ranked second nationally in total aircraft opera-
tions. It was outranked only by O’Hare (ORD),
the busiest airport in the world. At the time of
this study (March 1972), some of the training
activity that had accounted for much of OPF'’s
large volume of traffic had been dispersed to
other airports and the annual traffic count had
been reduced to 389,062. As a result, OPF is
now ranked 10th nationally in total aircraft
operations.

Work of the type and intensity of that at OPF
is found at only a few facilities in the country;
therefore, research was indicated to quantitate
stress in OPF controllers and relate this stress
to that in controllers at other facilities. Esti-
mates of stress at other ATC facilities are in-
cluded in this report; however, stress at those
facilities will be discussed in subsequent reports.

IL. Methods.

The OPF tower was manned by nine journey-
men, three trainees, and two supervisors, all of
whom volunteered to participate in this project.
Controllers at OPF worked a 5-day week con-
sisting of either 2 days and 3 evenings or 3 days
and 2 evenings. Observations were made on each
of the 14 controllers on two consecutive day
shifts. Time limitations on the project precluded
additional observation.

On reporting for work, subjects were fitted
with sensors and ECG tape recorders to enable
the continuous recording of electrocardiograms
(ECG) throughout the work period.’ (The

procedure for making this recording has been
described in a previous report.) An observer
kept an activity log so that heart rates (HR)
were related only to periods of air traffic control ;
je. all off-position periods were excluded from
the data at the time of tape playback.

Subjects collected morning urine specimens
on each of the 2 days of their participation.
These specimens, which consisted of urine formed
during night sleep, were used for determining
baseline values of 17-ketogenic steroids (st),
epinephrine (e), and norepinephrine (ne). Sub-
jects were asked to void before going on duty
and to collect (in special plastic bottles) all the
urine subsequently formed during the 8-hour
work period.

Urine specimens were preserved by means of
dry boric acid placed in the collection bottles.
The specimens were cooled in insulated cases
during the collection periods and were stored in
a freezer immediately after the collection periods.
The frozen specimens were shipped by air freight
to the Aviation Physiology Laboratory at the
FAA Civil Aeromedical Institute, Oklahoma
City, and remained frozen until they were
thawed for analysis. All values for steroids and
catecholamines were expressed as micrograms
per 100 milligrams of creatinine.

The ATC workload was recorded on tape as
the total radio transmission time (incoming and
outgoing calls) for each subject while he was on
the Ground Control, Local Control 1, or Local
Control 2 position. Local Control 1 handled
traffic on Runway 9L/27R; Local Control 2 han-
dled traffic on 9C/27C and 9R/27L. Prevailing
winds were easterly, so other runways were
rarely used. No workload was recorded for the
Flight Data (FD) position because no radio
transmissions were involved.



‘Taste 6.

Ca, Cat, Co, aNd Cae for Hach ATC Facility Studied (Ranked by C.)

Facility cy Sot Se —TM
FIw ARTCC 0% 0.22 0.58 0.20
TAK 0.60 0.66 0.34 0.81
OAK 0.60 0.62 0.76 0.43
TAH ('71) 0.68 0.89 0.62 0.52
TAH ('70) 0.74 1.27 0.29 0.65
MIA ARTCC 0.76 0.61 0.71 0.96
ATL ARTCC 0.82 0.76 0% 1.37
OPF 0.84 0.64 0.74 1.15
ORD 1.08 1.41 0.75 0.98

TaBLeE 7. Ranking of Cs, Cat, Ce, and Coe for Each ATC Facility Studied
Facility c, Facility Cot Facility fe Facility Sue
FTW ARTCC 0.3% IW ARTCC 0.22 TAH ('70) 0.29 FTW ARTCC 0.20
AK 0.60 ‘MIA ARTCC 0.61 ATL ARTCC 0.44 OAK 0.43
OAK 0.60 OAK 0.62 TAX 0.34 TAH (*71) 0.52
TAH ('71) 0.68 OPF 0.64 FIW ARTCC 0.58 TAH ('70) 0.65
‘TAH ('70) 0.74 AX 0.66 TAH ('71) 0.62 TAX 0.81
‘MIA ARTCC 0.76 ATL ARTCC 9.76 MIA ARTCC 0.71 MIA ARTCC 0.96
ATL ARTCC 0.82 TAH (171) 0.89 OPF 0.74 ORD 0.98
OPF 0.84 TAH ('70) 1.27 ORD 0.75 Orr 1.15
ORD 1.05 ORD 1.41 OAK 0.76 ATL ARTCC 1.37

Taste 8. Correlation Coefficients of C., Cee, Co, and Cae and Workload
Workload

Cot Cae (transmission time)

c 70% BLE 88% 64
8
Cot - 59% +38 19
- - . 2 77ee
fe 52
ne - - - 55%
* P< .05

Ps 01
wee Ps 001


Taste 3. Comparison of Urinary Excretion of Stress Indicators by OPF Controllers (yg/100 mg Creatinine)

st e ne
Subject BY ek B w B w

1 453.9 745.9 0.48 1.99 3.62 8.64
2 542.7 1334.6 0.47 2.60 3.66 4.68
3 282.8 1021.1 0.30 0.93 1.64 2.81
4 870.8 1226.4 0.53 3.17 2.86 6.65
5 242.1 652.0 0.46 1,80 1.55 3.51
6 611.4 1076.9 0.49 2.49 3.47 4.38
7 448.2 1162.0 0.39 1.44 2.09 4.30
8 717.6 1344.9 0.40 1.77 2.29 5.61
9 392.2 673.8 0.38 Lu 1.95 3.36
10 592.1 1457.8 0.57 2.10 2.77 4.06
poy 429.4 666.4 0.46 1.56 2.61 4.00
2 634.3 752.3 0.36 1.21 2.68 3.07
13 804.8 935.3 1.02 2.25 3.32 6.52
uw 719.9 1024.8 0.72 1.43 4.73 7.27
x 553.0 1005.3 0.50 1.85 2.80 4.91

*B @ Baseline value
wi = Work value

Our index, expressed as “C,,” is calculated
from the urinary content of st, e, and ne ex-
pressed as micrograms per 100 milligrams of
creatinine. Though the creatinine-based ratio is
not necessary for computation of this index, it
was chosen because of uncertainties regarding
urine collection periods and urine volumes that
were inherent in specimens collected in the field
under conditions not as strictly controlled as
they might be in the laboratory. Any other
basis for expression of excretion of these sub-
stances would be equally useful provided the
units were consistently used throughout the cal-
culation. Because the three compounds occur in
the approximate ratio of 500 st:10 ne:1 e, some
weighting procedure was necessary to prevent st
from being the sole determinant of the index.

Weighting was accomplished by dividing the
individual night sleep (baseline) and work
(response) values of each metabolite by the mean
of all the values of each metabolite in the entire
controller population from which data have been
collected in the nine studies carried out to date.

This weighting factor, referred to as the “grand
mean” and expressed as “Xo,” is calculated for

gach metabolite (2, Figure 1). The stability of

Xq is essential if valid comparisons of C, are to
be made, for if Kg changes, so do all the C,
values calculated prior to the change. More than
2,000 observations have been made on 210 con-
trollers, and all of these data were entered in a
Hewlett-Packard 2100A computer. Xa was re-
computed as each observation for e, ne, and st
was added. The initial variation was large, but
by the time 2,000 observations had been recorded,
the variation was reduced to less than 5 percent.
If C, previously calculated is changed as a result
of a change in Xg, the numerical value of C, only
will change; the comparative ranking will not
change.

For reasons to be discussed later, it is desirable
to integrate the baseline and response values.
This procedure is carried out simply by obtain-
ing the product of the weighted baseline value
and weighted response value for each metabolite.



Taste 1. Percent Change in Heart Rate (HR) by Subject

Subject Resting ER

1 95

2 68

3 78

4 90

5 88

6 69

7 61

8 93

9 78

10 60

i 65

12 15

13 nm

“ 86
Ill. Results.

Heart Rate. The preshift HR of each subject
was determined with the subject standing while
the recording equipment was tested at the time
of electrode application. The percent change in
HR for each subject from the preshift condition
to the working condition is listed in Table 1.

While there were no significant differences in
HR between the three radio positions at OPF,
there was a difference (P<0.02) between the
Local Control 1 and FD positions.

When all comparable work positions at various
ATC towers are considered (Table 2), HR’s at
OPF were 9 percent higher than those at ORD
in 1968 (P<0.01), 18 percent higher than those
at Houston Intercontinental Tower (IAH) in

Taste 2. Comparison of Heart Rates (HR) at OPF
with Three Other ATC Towers

UR (avg bpm) 2
Orr other

92 (ORD) 8% 0.01
92 (IAH '70) 78 0,001
92 (TAH '71) 82 0.05

Working HR % Increase (decrease)
99 5
86 26
96 22
99 10

108 23
68 aM
89 46
97 4
90 15
89 48
87 uu
93 25
90 27
97 12

1970° (P<0.001), and 12 percent higher than
those at TAH in 1971 (P<0.05).°

Urine Biochemistry. Table 3 lists 2-day av-
erages for st, e, and ne for each subject under
baseline and working conditions. For the group,
st excretion during work increased by 182 per-
cent over the baseline condition, e increased by
370 percent, and ne increased by 115 percent.

Comparison of ATC facilities is rendered dif-
ficult because the rankings of stress by metabolite
do not often agree. Ranking of stress by ne
excretion may not agree with the ranking of
stress by e or st. It thus became desirable, if not
imperative, to integrate the various biochemical
stress indicators into one number that would
represent stress.

A universal stress index has not been formu-
lated. Such an expression would be exceedingly
useful in bringing order out of the confusion
presently surrounding the subject. In this lab-
oratory has been devised a limited index that
falls short of universal application but is useful
within a given population that is homogeneous
with respect to the stressor (e.g., the air traffic
controller population). The calculation of this
index is presented in Figure 1.


Table 6 shows a ranking by C, of facilities cn. and is weakly correlated (P<0.05) with o.
studied. Values for cyt, Ce, and Cy, are also and that c, is not significantly correlated with
shown, and it is obvious that OPF ranks second —Cne.
highest of the facilities by virtue of high c, and Figure 2 shows in graphic form the relation-
Cae. In other words, work at, OPF is charac- ship between cst, Ce, and Cae and emphasizes that
terized by outputs from the sympathetic nervous QPF is mainly characterized by outputs from
system (ne) and the adrenal medulla (e). The the sympathetic nervous system and the adrenal
secretions from these two sources would be ex- medulla.
pected to result in temporarily elevated blood .
pressure, increased heart rate, quickened reaction Workload. Table 8 and Figures 3, 4, 5, and 6

show the relationship between Cs, Cst, Ce, and Coe

time, increased body heat, and increased alert- e » Coy ANE
ness. Table 7 shows a ranking of facilities by and workload defined as radio transmission time.
Coty Coy ANG Cree Workload is weakly correlated (P<0.05) with
Table 8 shows that C, at OPF is correlated Cz and Cx. and is strongly correlated (P<0.01)
significantly with cst, Ce and Cae. Table 8 further — with c. Workload is not significantly correlated

shows that c, is not significantly correlated with with cet.

Tasie 4. Biochemical Stress Index (Cs) Differences for Various ATC Facilities

Facility Se TAX OAK TAH (171) TAH ('70) MIA ARTCC ATL ARTCC OPF ORD
PTW ARTCC 0.34 0.26% “0.26% 0.34%* 0.400% 0.420% 0.48% 0.500% 0.710%
ax 0.60 - - 0.08 0.14 0.16 0.22 0.24 0.458
oaK 0.60 - - 0.08 0.14 0.16 0.22 0.24 0.45%
TAH ('71) 0.68 - - - 0.06 0.08 0.14 0.16 0.37%%
TAH ('70) 0.74 - - - - 0.02 0.08 0.10 0.31*
‘MIA ARTCC 0.76 - - - - - 0.06 0.08 0.29%
ATL ARTCC 0.82 - - - - - - 0.02 0.23
OFF 0.84 - - - - - - - 0.21
onD 1.05 - - - - - - - -

* Indicates P < .05
Indicates P ¢ .01

Tuncan's New Multiple Range Test

‘Taste 5. Biochemical Stress Index (Cs) Differences for Various ATC Facilities (Day Shift Only)

Facility Cy tax OAK ATL ARTCC MIA ARTCC = IAH ('71) OPF TAH ('70)
FTW ARTCC 0.39 0.21 0.21 0.25 0.37" 0.40% 0,45%% 0,530
TAK 0.60 - - 0.04 0.16 0.19 0.24 0.32
OAK 0.60 - - 0.04 0,16 0.19 0,24 0.32
ATL ARTCC 0.64 - - - 0.12 0.15 0.20 0.28
MIA ARTCC 0.76 - - - - 0.03 0.08 0.16
TAR ('71) 0.79 - - - - - 0.05 0.13
OPF 0.84 - - - - - = 0.08
TAH (170) 0.92 - - - - - - -

* Indicates P < .05
‘*e Indicates P Ss .01



Technical Report Documentation Page

T. Report No. 2. Government Accession No.

FAA-AM-74-11

3. Recipient's Cotalog No.

4. Title and Subtitle
COMPARISON OF OPA LOCKA TOWER WITH OTHER ATC
FACILITIES BY MEANS OF A BIOCHEMICAL STRESS INDEX

3, Report Date

December 1974

6. Performing Organization Code

7. Author's) C, E, Melton, J. M. McKenzie, J. T. Saldivar,
Jr., and S, M. Hoffmann

8. Performing Organization Report No.

9. Performing Orgenizotion Nome ond Address
FAA Civil Aeromedical Institute
P. 0. Box 25082

Oklahoma City, Oklahoma 73125

10. Work Unit No. (TRAIS)

TT. Contract or Grant No.

12. Sponsoring Agency Name ond Address
Office of Aviation Medicine
Federal Aviation Administration
800 Independence Avenue, S.W.
Washington, D.C. 20591

13. Type of Report ond Period Covered

OAM Report

14. Sponsoring Agency Code

T5. Supplementary Notes

Work was performed under Task AM-B-73-PHY-57.

6. Abstract

Physiological and biochemical measurements of stress in 14 Opa Locka Tower (OPF)
controllers indicated that the principal stressor at that facility was the heavy
volume of air traffic. Controllers responded to this stressor with a large
increase in urinary output of catecholamines. A stress index, C,, shows that OPF
ranks second in stressfulness in the nine stress studies carried out at eight
ATC facilities. Baseline values show that off-duty stress at OPF is low. The
results of this study emphasize that a battery of tests is necessary for adequate

definition of stress in this personnel group.

17. Key Words 18. Distribution Statement
Stress index, Urinary stress indicators, |Document is available to the public through
Heart rate the National Technical Information Service,

Springfield, Virginia 22151

19. Security Classif. (of this report) 20. Security Classif, (of this page)

Unclassified Unclassified

Bi No. of Pages | 22. Price

$3.00 PC
i 95 MF

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



ha!
1.2

7

. OPM LOCcKM TOWER
= x“

al be x

“ea so sea 73 en aa 1en

WORKLOAD <MIN>

Fieure 3. Relationship between Cs and workload represented by minutes of radio communication time.

1.2
x
a
x
1.
x
2
8 x x *
Gr 7 x
6
= x
al
x
-a 4X x
OPA LOCKA TOWER
.2
x
ue se sa 72 en so ime
WORKLOAD <MIN>

Fievre 4. Relationship between cat and workload represented by minutes of radio communication time.

8


2
MIA
oPF

to
lo
fo

0.6 O07

o8 Ce

fone TAH ('7 1),

Froure 2, Graph of the relationship between Cet, Cae, and Ce.

IV. Discussion.

Even though OPF’s air traffic congestion is
considerably below its historic high level, it is
still an extremely busy airport. In good weather,
radio traffic on local control is virtually contin-
uous. The OPF controllers respond to this
workload with e and ne outputs that place them
next to ORD controllers and are not significantly
different from theirs. ORD controllers are
ranked first because of their heavy adrenocortical
output. At OPF, cne exceeds and ¢, effectively
equals those values for ORD controllers.

The stress index presented in this paper is
essentially a product, rather than a ratio, of

normalized baseline and work-related values.
‘As such, the baseline values are coequal with the
response values in defining the level of stress of
an individual or, by aggregation of individuals
in the same place, of a facility. Others? have
used an index based on the work-to-baseline
ratio. Such an index may show a high degree
of stress when the baseline is low and the re-
sponse is only moderate; conversely, it may show
a low stress response when the baseline is high.
Further, the ratio index is based on the assump-
tion that the output of stress indicators will
increase as a result of activity; such may not be
the case. Occasionally, the activity-related



CALCULATION OF STRESS INDEX

|. Epinephrine (e)

Response Axis

< Norepinephrine (ne)

<< 17-Ketogenic steroids (st)

@ Epinephrine
Norepinephrine
B@ |7-Ketogenic steroids

Baseline Axis

2. For each metabolite,

a) Obtain a Grand mean (X,)
Xg == XgtZYe,
n

Xp, = All baseline values.
Yr = All response values.

b) Weight each individual baseline value (X) and each individual response

value (Y).

i
tL ew, =
x, (We

Weighted baseline value.

Weighted response value.

c) Compute product (c) of baseline and response values for each metabolite.

(c) = (Wg) (Wp)

3. Compute Stress Index (Cg) by averaging c- values of all metabolites.

Cy = (Cg + Chet Cot)
3

Fieure 1,

(1) Diagrammatic illustration of the disproportionate amounts of st, ne, and e in urine; (2) method of

weighting st, ne, and e to make each of them equally representative in (3) the calculation of the stress index

Cs.

This product is expressed as “c” (2, Figure 1).
Thus, there are cs:, Ce, aNd Cue.

The final index, C,, is obtained from the aver-
age of Csi, Ce, and Cpe (3, Figure 1). The average
is used so that the index can be expanded to
include other measurements. Since C, is dimen-
sionless, any other measurement for which there
are baseline and response values can be added.

C, can be computed for individuals, for fa-
cilities, for various work positions, for any par-
ticular work shift, or for any other condition.
The requirements are that there be baseline and
response data and that there be sufficient data
from which a reliable grand mean can be com-
puted. C, has been computed for each controller

who participated in the nine studies carried out
at eight ATC facilities. Table 4 shows the dis-
tribution of C, by facility and the level of sig-
nificance of the difference between each of them.

Table 4 shows that OPF ranks second in
stressfulness to ORD, the highest stress facility
on the list, and is not significantly different from
ORD. OPF is significantly different from Fort
Worth ARTCC (FTW), the lowest stress facil-
ity on the list. Results from other facilities are
listed and will be discussed in future reports.

Since data were obtained at OPF only on the
day shift, comparison of OPF day shift C, with
day shift C, at other facilities is presented in
Table 5. Again, OPF is significantly different
only from FTW.




‘Taste 9. F-Ratios and Significance of Difference of Baselines and Response Levels at ATC Facilities

st
Baseline 7.6428 (P < 0.01)
Response 7.5573 (P < 0.01)

The baseline values at OPF are low, an indi-
cation that off-duty activities, generally speak-
ing, have a low stress content. Life for this
group does not appear to be characterized by
continual high-level stress. Kagan and Levi*
emphasize that adrenal cortical stimulation oc-
curs as a final common (nonspecific) response to
a great variety of stimuli but that the anterior
pituitary-adrenal cortical axis is slower to re-
spond and is less sensitive than is the hypothala-
mic-sympathetic-adrenal medulla axis. OPF
controllers do respond with a moderate increase
in adrenal cortical output, but the major response
is via the hypothalamic-sympathetic-adrenal
medullary system. This response is strongly re-
lated to workload, whereas steroid excretion is
not.

The elevated HR exhibited by OPF control-
Jers is a cardiovascular manifestation of sympa-
thetic arousal shown also by elevated catechola-
mine excretion. The increase in metabolic rate
attendant on the intensity of the work is also
evidenced by the elevated e excretion. These
biochemical indicators confirm what is so evident
from observation of these controllers as they
work—that in their intense involvement in con-
trolling aircraft in a highly congested airspace,

0.7501 (N.S.)

ne

——_

2.3995 (P < 0.05)

4.1895 (P = 0.01) 9.2499 (P < 0.01)
these men are responding in the classical manner
described by Walter B. Cannon.’

Although a meaningful definition of stress has
not yet been proposed, it is clear that, at least
for now, any estimate of stress will have to rely
on a battery of tests that will provide insights
into the functioning of more than one system.
Clearly, the reason for this is that the body’s
response to a stimulus is not absolutely non-
specific and there is some degree of stimulus-
response specificity.

This concept is revealed by the use of the in-
dex and is illustrated in Tables 6 and 7. For
example, C, for Houston Intercontinental Tower
(IAH) in 1970 is disproportionately influenced
by cst, whereas C, for Atlanta ARTCC (ATL)
is disproportionately influenced by Cre and Ft.
Worth ARTCC (FTW) by c. Factors: that
were identifiable at those facilities probably ac-
counted for the differential response. Certainly,
the data from OPF clearly indicated a strong
correlation between catecholamine excretion and
our workload concept. Likewise, the low cst ap-
pears to indicate that stress at OPF is not suf-
ficiently strong or continuous to cause the high
level of steroid excretion that is evident at some
other facilities.

References

. Cannon, W. B.: Bodily Changes in Pain, Hunger,
Pear, and Rage, Boston, ©. T. Branford, 1929.

. Hale, H. B, J. ©. Duffy, J. P. Hillis, and BE. W.
Williams: Flying Stress in Relation to Flying Pro-
ficiency. USAF School of Aerospace Medicine Tech-
nical Report No. 64-88, 1964.

. Kagan, A. R., and Lennart Levi: Health and En-
vironment-Psychosocial Stimuli, A Review. Reports
from the Laboratory for Clinical Stress Research,
No, 27, December 1971.

. Melton, ©. B., J. M. McKenzie, B. D. Polis, G. E.
Funkhouser, and P. F. Iampietro: Physiological
Responses in Air Traffic Control Personnel: O’Hare
Tower. FAA Office of Aviation Medicine Report
No, AM-71-2, 1971.

h

5. Melton, C. E., J, M. McKenzie, B. D. Polis, S. M.
Hoffmann, and J. T. Saldivar, Jr.: Physiological
Responses in Air Traffic Control Personnel: Houston
Intercontinental Tower. FAA Office of Aviation
Medicine Report No. FAA~AM-73-21, 1973.

Melton, ©. E., J. M. McKenzie, R. ©. Smith, B. D.
Polis, E. A. Higgins, 8. M. Hoffmann, G. BE. Funk-
houser, and J. T. Saldivar, Jr.: Physiological, Bio-
chemical, and Psychological Responses in Air ‘Traffic
Control Personnel: Comparison of the 5-Day and
2-2-1 Shift Rotation Patterns. FAA Office of Avia-
tion Medicine Report No. FAA~AM-78-22, 1978.

. Saldivar, J. T., Jr.: A Simplified Technique for
Rapid Application of Dry ECG Hlectrodes. AERO-
SPACE MED. 4:456, 1970.

a



Acknowledgment

The authors would like to thank Mr. Carlton Hamilton, Chief, Opa
Locka Tower, for his enthusiastic support and many kindnesses during the
course of this project. Our special thanks go to the OPF controllers who
served as volunteer subjects, often to their discomfort and inconvenience.





x
1
14
1.2
Cei.s
7)
6
><
4 DPR LOCKR TOWER
be x
x
ue sB 5B 728 eo se 128
WORKLOAD <MIN>

Froure 5. Relationship between ce and workload represented by minutes of radio communication time.

he 1s

OPA LOCKA TOWER

un

2 72 an 2 ioe

WORKLOAD <M«iN>

Fiaure 6. Relationship between Cae and workload represented by minutes of radio communication time.

9