ACKNOWLEDGMENTS

The authors thank all Civil Aeromedical Institute (CAMI) staff who helped make this
project a success, particularly the members of the Protection and Survival Laboratory and the
CAMI Clinic. Special thanks go to Southwest Airlines personnel JoAnne Harris, Julie
Humphries, Julie Bryant, and Sandra Pool, who ensured our ability to have “line” flight
attendants support our study. Thanks also to Carol Armstrong, LB&M Associates, for her
dedicated data reduction and statistical support, and to Richard Harris, of Harris Housemoving
Company, for stabilizing the aircraft cabin evacuation facility above the ground. Thank you all.

iii


Figure 2. Platform Egress Route

An active-duty airline flight attendant was sta-
tioned at the active Type-I exit to remove the exit
covering and to encourage and assist subjects, as
needed. A second flight attendant was stationed across
the cabin at the inactive Type-I exit to block subject
flow through that exit and redirect any straying
subjects toward the active exit. The same 2 flight
attendants were employed throughout the study;
both were required to serve as the active-exit atten-
dant. Other members of the research team were
located at the end of the slide or the inclined ramp to
assist subjects and to guide them away from the exit
area after they had deplaned. Medical personnel were
also in attendance in the event of injury.

Motivation. Subjects were instructed that the
evacuations were intended to simulate actual emer-
gencies, and that they should egress as fast as possible.
At the start of each trial, the flight attendant at the
active exit would shout commands to unbuckle seat
belts and come forward to the exit. The active-exit
flight attendant continued to shout evacuation com-
mands and gesture enthusiastically (per airline train-
ing) throughout every trial; the other flight attendant
redirected straying subjects to the active exit.

Procedure. Prospective subjects were given a gen-
eral explanation of the purpose of the study and
detailed information about the procedures to be
used. Visual information and briefings about how to
use the inflatable escape slide were also provided
prior to the subjects giving informed consent.

Once entered into the study, subjects also com-
pleted a personal demographics questionnaire, and
had their height, weight, and waist size noted for
anthropometric analysis. They were then escorted to
the ACEF to become visually familiar with the egress
systems and to prepare for the trials. The subjects
were issued boarding cards with random seat assign-
ments, and they seated themselves accordingly.

After the briefings describing the experiment were
read, they were allowed to ask additional questions.
When these activities were completed and the sub-
jects indicated their readiness, the principal investi-
gator exited the cabin to avoid interference with the
trial. The buzzer used to indicate the beginning of the
trial was sounded after some variable interval of 30
seconds or less.

At the start of the trial, the 2 flight attendants were
stationed at the front of the cabin, 1 by each of the
Type-I exits. Immediately upon the sound of the


AIRCRAFT EVACUATIONS ONTO EscaPE SLIDES AND PLATFORMS II:
EFFects oF Exit SIZE

INTRODUCTION

Ina prior report, McLean, George, Funkhouser &
Chittum (1996) described the effects of manipulat-
ing passenger motivation levels during aircraft evacu-
ations conducted through Type-I floor-level transport
category aircraft (airliner) exits. In that study passen-
gers deplaned onto both an inflatable escape slide and
doorsill-height platform scaffolding attached to the
Aircraft Cabin Evacuation Facility (ACEF) at the
Federal Aviation Administration’s Civil Aeromedi-
cal Institute (CAMI).

Those experimental treatments had been chosen
because: 1) differences in passenger motivation levels
had been found to be associated with significant
differences in passenger behavior during simulated
aircraft evacuations (e.g., Muir, Marrison, & Evans,
1989; McLean, Chittum, Funkhouser, Fairlie, &
Folk, 1992), and 2) doorsill-height platforms had
been used as the escape route in a 1992 full-scale
evacuation demonstration conducted to support a
Code of Federal Regulations (CFR) § 25.803 analysis
for certification of the McDonnell Douglas MD-11
airplane.

In the MD-11 demonstration the time for comple-
tion of the aircraft evacuation conducted onto the
platforms was significantly reduced, compared with
the time for evacuation of the same MD-11 airplane
when passengers egressed onto the inflatable escape
slides. Importantly, doorsill-height platforms had also
been used in some of the motivational research para-
digms used to study passenger evacuation behavior (see
Muir et al., 1989; Muir, Bottomley, & Hall, 1992).

The differences in the results of those independent
activities had made comparative interpretation of the
associated findings difficult; the use of a single evacu-
ation facility fitted with both an inflatable escape
slide and a doorsill-height platform to further study
aircraft evacuation performance was intended to al-
low better explanations of those differences.

The results of the first study (McLean et al., 1996)
were instructional, as the previously established ef-
fects on egress of using doorsill-height platforms, as
compared with inflatable escape slides, were replicated.

Additionally, discriminative effects of high and low
passenger motivation levels were found. When com-
bined, however, the effects suggested a complex rela-
tionship controlled in part by forces additional to the
motivation and egress route treatments, indicating a
need for further investigation.

The study reported here was designed to address
this need, studying the effects of differences in exit
size (height of the opening) on egress using both
escape routes. Exit size was chosen as an experimental
treatment for two reasons. First, the increased ergo-
nomic requirements attendant to egress at shorter
exit heights were expected to provide additional dis-
criminative value regarding differences in evacuation
performance onto inflatable escape slides versus door-
sill height platforms. Second, there were relatively
few research data on 2 new types of floor-level exits
that have been certificated for use on transport cat-
egory aircraft.

Following the MD-11 full-scale demonstrations
and the McLean et al. (1996) study, it was hypoth-
esized that egress onto the doorsill-height platform
would be generally faster than that onto the inflatable
escape slide, owing to both the ease of egress onto the
floor-level platform, versus the descending escape
slide, and the general hesitancy found when evacuees
are faced with using inflatable escape slides. Such a
finding would be the second replication of the initial
effect found. Prior evacuations through the floor-
level exit onto the platform has been shown to be
equivalent to walking or running through a typical
door from one room to another ina building, whereas
egress onto steeply descending escape slides has gen-
erally caused evacuees to either sit before sliding, to
gather themselves in preparation for jumping onto
the slide, or to hesitate to use the slide in any fashion.
The smaller exit sizes were expected to exacerbate
these effects, as mounting the escape slide through
shorter exit openings was theorized to be psychologi-
cally more challenging and physically more difficult.
Thus, an interaction effect of exit height and escape
route was expected.




Table 2. Experimental Design

GROUP EXPERIMENTAL TRIAL SERIES
1 P48 S60 P72 $48 P60 $72
2 P60 $72 P48 S60 P72 S48
3 P72 S48 P60 $72 P48 S60
4 S48 P72 S60 P48 $72 P60
5 S60 P48 $72 P60 $48 P72

* P = Platform; S = Inflatable slide; Exit height = 48, 60, or 72 inches

gure 1. Slide Egress Route



DOT/FAA/AM-99/10

Office of Aviation Medicine
Washington, D.C. 20591

Aircraft Evacuations onto
Escape Slides and Platforms
Il: Effects of Exit Size

Garnet A. McLean
Mark H. George
Gordon E. Funkhouser
Charles B. Chittum

Civil Aeromedical Institute
Federal Aviation Administration
Oklahoma City, Oklahoma 73125

April 1999
Final Report

This document is available to the public
through the National Technical Information
Service, Springfield, Virginia 22161.

@

U.S. Department
of Transportation

Federal Aviation
Administration


Egress Time in Seconds

35

Clear bars show standard deviation p<.02

80 fone nee eee ene ete t eee eeeeeee scenes

25 feerereeef 0 fe ee eee ee ee eee eee

2

15

Te eee

48" 60"
Door Height
Figure 4. Main Effect of Exit Size

Egress Time in Seconds

10

48" 60" 72"
Door Height
“F Slide  -* Platform
Figure 5. Interaction Effect of Egress Route and Exit Size


buzzer, the curtain covering the active exit was re-
moved by the associated flight attendant, who then
began shouting and gesturing for the subjects to
unbuckle their seatbelts and proceed through the
exit. After the evacuation trial was completed, sub-
jects were re-grouped, given new random seating
assignments, and boarded for the next trial.

RESULTS

The videotape recordings of each trial were examined
to obtain total evacuation times, which were analyzed
using SPSS for Windows®, version 6. Total evacuation
time was defined as beginning at the time the start
buzzer initially sounded and lasting until the 28th
subject had cleared the Type-I exit opening. The reduc-
tion in analyzed group size (as compared with the
subject group sizes listed in Table 1) occurred because
one of the groups incurred the bulk of the injuries
mentioned above. The other group data were truncated
to allow appropriate statistical comparisons. A 2-way
(egress route x exit opening size) repeated-measures
analysis of variance found a within-group main effect of
egress route (p < .001; Figure 3) and a within-group
main effect of exit size (p < .012; Figure 4). The
interaction of egress route with exit size produced a
nearly significant trend (p<.062; Figure 5) that may
have achieved significance had the study design not
been truncated.

a5

A simple effects analysis found this trend to result
from a within-group effect of exit size produced when
subjects used the inflatable slide (p < .017) but not
the platform (p < .41). This effect appeared to result
from the effects of subject hesitation at the exit fitted
with the slide, coupled with the increased ergonomic
demands of entering the slide, especially at the lesser
exit heights. These effects reveal the strong role that
egress route had on the evacuations, particularly
when the exit sizes were reduced.

DISCUSSION

The effects of egress route on evacuation rates were
shown to be significant, as the doorsill-height plat-
form allowed much faster evacuations than the inflat-
able slide. Subject hesitation at the exit fitted with the
slide was the governing principle for this effect; egress
onto the platform was equivalent to going unim-
peded (except for the exit height-reducing plug) from
one room through a door into another room in a
building. In contrast, use of the slide required sitting,
with its need for additional behavioral preparation,
or a downward leap onto the slide surface, which
required both behavioral and psychological prepara-
tion. As also seen in McLean et al. (1996), having to
jump onto the slide produced individual subject
hesitations before many of the subjects would jump;

ars show standard deviation

Egress Time in Seconds

Plattorm

p<.001

Slide

Egress Route

Figure 3. Main Effect of Egress Route


The knowledge to be gained in the study was
intended to prove informative for two purposes: 1)
the use of exit size to further probe the experimental
effects related to egress means (escape slides versus
doorsill-height platforms) would enhance the evalu-
ation of diverse aircraft evacuation data, and 2) direct
examination of the different exit sizes would signifi-
cantly expand knowledge relevant to egress and air-
craft evacuations through the newly certificated exit
types. A final benefit would be to further delimit
methodological issues that need to be considered in
research designs related to questions about current
and future aircraft evacuation systems and procedures.

METHODS

Subjects. The subjects in this experiment were 174
human adults between 18 and 40 years of age. They
were divided among 5 experimental groups; Table 1
provides demographics for each group.

Subjects were required to wear long-sleeved shirts
and long pants, as well as low, flat-heeled shoes. They
were also naive about, and had never participated in,
emergency aircraft evacuations.

Design. A 2 (egress route) X 3 (exit height) re-
peated-measures, research design was employed in
the study. Egress route (platform or slide) and exit
height (48, 60, 72 inches) were counter-balanced
across evacuation trials, providing 6 subject groups
using 6 different trial orders. However, several sub-
ject injuries occurred near the end of the study. A
resultant review of the project suggested that the
completed trials had answered the experimental
question satisfactorily; thus, the study was truncated
after the Sth group had completed its trial series.

Table 2 displays the completed experimental design.

Apparatus. The ACEF was configured as a B-737,
with rows of triple seat assemblies placed 6 abreast in
the cabin. The ACEF was raised to position the floor
at the nominal doorsill height of 8 feet 9 inches above
the ground. A 72-inch x 30-inch Type-I exit located
forward of all seats was fitted with an inflatable single
lane slide attached to the exit threshold by a typical
girt bar. Foam-rubber tumbling pads were placed on
a net positioned directly underneath and around the
slide to protect against injury from inadvertent falls
(see Figure 1).

Across the fuselage, another 72-inch x 30- inch
Type-I exit provided egress onto a 20- x 20- foot
square doorsill-height platform, which transitioned
to the ground via a 10 foot-wide, 35 foot-long ramp
extending from the platform directly perpendicular
to the exit and declined at a 15 degree angle (see
Figure 2). Both exits were modified to allow place-
ment of removable plugs at the top of the exit opening
by which to reduce exit height to 60 or 48 inches.
Both exits were also covered with fabric curtains
(simulated doors) that were individually removed, as
appropriate to the experimental condition, immedi-
ately upon the sounding of the start buzzer at the
beginning of each trial. These coverings were in-
tended to prevent subjects from viewing the exit
opening size before the trial began. Bulkheads with a
30-inch opening at the aisle were also situated in
front of the seat rows to further impair direct view of
the exit. Video cameras with timing capability were
situated parallel to the fuselage at the exits to archive
the evacuation data. During all trials the ACEF was
maintained at the CFR 25.812 minimum 0.05 foot-
candle emergency interior lighting level.

Table 1. Subject Attributes

GROUP AGE WEIGHT HEIGHT GENDER TOTAL
(yrs) (Ibs) (ins) M_F SUBJECTS

1 18-40 105-257 62-76 18 | 18 36
2 18-40 108-233 62-75 17_| 17 34
3 18-39 96-263 63-80 22 | 12 34
4 18-39 98-264 61-75 21 15 36
5 18-39 119-275 61-78 25 9 34

TOTALS 103 | 71 174





Technical Report Documentation Page

T. Report No. 2. Government Accession No. 3, Recipients Catalog No.
DOT/FAA/AM-99/10

4, Title and Subtitie 5, Report Date

Aircraft Evacuations onto Escape Slides and Platforms II: Effects of Exit Size | April 1999

7. Author) 8, Performing Organization Report No.
McLean, G.A., George, M.H., Funkhouser, G.E., and Chittum, C.B.

9. Performing Organization Name and Address TO. Work Unit No. (RAIS)

FAA Civil Aeromedical Institute
P.O. Box 25082
Oklahoma City, OK 73125

11. Contract or Grant No.

12. Sponsoring Agency name and Address 13, Type of Report and Period Covered
Office of Aviation Medicine

Federal Aviation Administration
800 Independence Ave.
Washington, DC 20591

15. Supplemental Notes 14, Sponsoring Agency Code

This work was performed under task AM-B-94-PRS-89.

16. Abstract
Experiments were conducted to examine the effects of exit height on subject flow rates during simulated
emergency evacuations from an aircraft fuselage. Egress was through (modified) Type-I exits, using inflatable
escape slides and doorsill-height platforms configured with ramps for descent to the ground. A single-aisle
aircraft simulator was equipped with 30-inch wide rectangular floor-level exits variously configured to achieve
overall exit heights of 48, 60, and 72 inches. Human research subjects, ranging in age from 18 to 40 years,
evacuated through the exits to the ground via both platform and slide egress routes. A (2 X 3) repeated-
measures, counterbalanced research design was employed to control trial order effects. Analysis of variance
revealed overall main effects of egress route (p<.001) and exit height (p<.012), and a nearly significant
interaction of egress route with exit height (p<.062). The main effects occurred because the egress onto the
platform was much faster than the slide, and egress slowed monotonically as the exit height was reduced. The
trend toward an interaction effect of egress route and exit size occurred because reducing the exit height to 48”
significantly slowed egress onto the inflatable escape slide (p<0.017) but not the platform (p<.41). This
discriminative effect resulted from the hesitation that subjects displayed when using the slide, relative to the
platform, especially at the shortest exit size studied. The increased egress time onto the escape slide appeared
to result from a more difficult entry onto the slide, as the lower door heights required subjects to bend over
more to enter the slide. This made the typical "jump-and-slide" maneuver much harder to perform. Egress
ratings for exits that conform to the dimensions used in this study should reflect these findings, especially
when escape slides are the likely egress route.

17. Key Words 18. Distribution Statement
Aircraft Evacuation, Motivation, Escape Slide, Document is available to the public through the
Competitive Behavior National Technical Information Service,
Springfield, VA 22161
19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No, of Pages 22. Price
Unclassified Unclassified ll

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


NOTICE

This document is disseminated under the sponsorship of
the U.S. Department of Transportation in the interest of
information exchange. The United States Government
assumes no liability for the contents or use thereof.


the cumulative effects of the behavioral adjustments
and these added hesitations were responsible for the
main effect of egress route seen.

The effects of reducing exit height were also shown
to be significant, as the 48-inch high exit produced
significantly lower evacuation rates, as compared
with both the 60- and 72- inch exit sizes. However,
this effect was essentially limited to egress onto the
escape slide, and appeared to result from the in-
creased ergonomic difficulty of having to bend over
before jumping onto the slide. The statistical trend
seen toward a hyperadditive interaction of egress
route and exit size affirms this added difficulty, as
does the main effect of exit height when evacuees
used the slide but not the platform. In summary, as
the exit height was reduced, egress onto the slide
slowed significantly; in contrast, rates onto the plat-
form remained consistent for all exit heights.

The lack of exit size effects when using the door-
sill-height platform occurred because the behavioral
and psychological demands of the platform did not
compare well with those of the escape slide. Evacuees
were simply not as challenged as they were when
using the slide. Thus, the doorsill-height platform
masked the effects produced by reducing the exit size,
thereby limiting its own acceptability as a research
tool in evacuation studies. Proposed use of this type of
egress means should be examined closely for validity.

These effects indicate that, in general, the type of
egress means employed in experimental evacuations
is important to the results obtained. In particular,
platforms, egress ramps, flaps, escape slides with odd
geometry’s, and/or other means of egress different
from current escape slides could all be expected to
generate differential effects on egress. This implies
that evacuation results obtained with one type of
egress means should not be casually generalized to
any other.

In addition to these considerations, several other
variables are likely to be important to evacuation
results, even when the evacuations are conducted
through floor-level exits onto escape slides. Extremely
tall doorsills, very long escape slides, extreme descent
angles, emergency lighting system differences (when
appropriate), and variances in crew procedures are
also likely to be important considerations. Thus,
results obtained with one type of escape slide should
not necessarily be generalized to another escape slide.

Together, these findings confirm that specific as-
pects of the egress route utilized in any aircraft
evacuation study are important contributors to the
results evidenced. The physical and psychological
demands attendant to any particular egress means
appear to impact the results substantially, rendering
interpretation of the results difficult without appre-
ciation of those associated demands.

When combined with the results found by McLean
et al. (1996), it becomes clear that evaluations of
future aircraft designs and evacuation systems, espe-
cially those that differ significantly from the systems
in use today, will require careful attention to the
apparatus and procedures used, in order to assure that
the results are valid and reliable.

Studies designed to model evacuations of a spe-
cific aircraft should use that aircraft’s actual evacua-
tion means to obtain the highest fidelity possible.
Similarly, studies intended to answer general ques-
tions about the consequences of specific factors on
egress must be carefully controlled to assure that the
results can be interpreted adequately and generalized
appropriately. As a corollary, the use of special appa-
ratus or procedures to demonstrate compliance with
regulatory requirements should be carefully weighed.

REFERENCES

1. Code of Federal Regulations, Title 14, Aeronau-
tics and Space, Vol. 1, U.S. Government Printing
Office, Washington D.C., January 1, 1997.

2. McLean, G.A., M. H. George, G. E. Funkhouser
and C. B. Chittum, Aircraft Evacuations Onto
Escape Slides and Platforms I: Effects of Passen-
ger Motivation, Office of Aviation Medicine Re-
port, DOT/FAA/AM-96/18, June 1996, National
Technical Information Service, Springfield, VA
22161.

3. Muir, H., D. Bottomley, J. Hall, Aircraft Evacu-
ations: Competitive Evacuations in Conditions
of Non-Toxic Smoke, Civil Aviation Authority
UK, Paper 92005, March 1992.

4. Muir, H., C. Marrison, & A. Evans, Aircraft
Evacuations: The Effect of Passenger Motiva-
tion and Cabin Configuration Adjacent to the
Exit, Civil Aviation Authority UK, Paper 89019,
November 1989.