Transcript Recent Transport Canada safety research at Cranfield University & Helen C. Muir

Recent Transport Canada safety
research at Cranfield University
Rebecca L. Wilson, Lauren J. Thomas
& Helen C. Muir
Human Factors Group
School of Engineering
Cranfield University, UK
Recent Research
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Considerable research has been conducted into the operation of
the Type III exit, however much of this work has been conducted
in a 3x3 configuration.
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Relatively little is known about whether the research findings
generalise to a 2x2 configuration.
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Transport Canada have commissioned three preliminary studies
into the operation of the Type III exit in a 2x2 configuration.
Study 1:- 2x2 and 3x3 cabin configuration
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Test facility was a Boeing 737 cabin simulator configured in
either:
3x3 or 2x2 configuration
10” or 13” VP in Type III exit row
Participants:
24 independent groups of up to 20 participants, six groups per
condition.
Dependent variable:
Egress time
Exit availability time
Boeing 737 cabin simulator 3x3
Boeing 737 cabin simulator 2x2
Procedure

Participants were greeted by a researcher trained and dressed
as cabin crew. After check-in, participants boarded the cabin
simulator.
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Seats for each group were pre-allocated according to a random
seating plan.
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Each group of participants were given a typical pre-flight safety
briefing.
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A minimal briefing was also provided to the passenger seated at
the Type III exit (Cobbett, Liston & Muir, 2001).
2x2 and 3x3
Evacuations
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On completion of the safety briefing, passengers heard a
recording of engine noise, followed by an announcement from
the Captain to “Undo your seatbelts and get out!”
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The cabin crew member then instructed passengers to open and
move towards the Type III exit.
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Throughout the evacuation, the cabin crew used assertive,
positive and concise commands to encourage passengers to
move as quickly as possible (Muir & Cobbett, 1996).
2x2 and 3x3
Results
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Data on evacuation times was extracted from video footage
recorded outside the Type III exit. Each participant was deemed
to have evacuated when both feet were on the wing.
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Data were available from a total of 24 evacuations – six trials
within each condition.
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Since the group size varied due to non attendance, all
evacuation time analyses used only the times for the first 15
people to evacuate through the exit.
2x2 and 3x3
Mean evacuation times 1st 15 (in secs)
Seating configuration
Total
Vertical
projection
3x3
2x2
10”
19.0
(sd 5.8)
18.1
(sd 5.3)
18.6
(sd 5.6)
13”
18.8
(sd 5.7)
17.3
(sd 4.9)
18.1
(sd 5.3)
Total
18.9
(sd 5.7)
17.7
(sd 5.1)
2x2 and 3x3
Evacuation results
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Inferential statistical analysis showed that there were statistically
significant differences due to the seating configuration.
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Participants evacuated quicker in the 2x2 configuration than the
3x3 configuration. This effect may be due to passageway length.
The result was unlikely to have arisen by chance.
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There were no statistically significant differences in evacuation
times due to vertical projection, nor an interaction between
seating configuration and vertical projection.
2x2 and 3x3
Mean exit availability times (in secs)
Seating configuration
Total
Vertical
projection
3x3
2x2
10”
10.2
(sd 3.0)
8.1
(sd 1.6)
9.1
(sd 2.5)
13”
9.4
(sd 2.1)
8.6
(sd 0.8)
9.0
(sd 1.6)
Total
9.8
(sd 2.5)
8.4
(sd 1.2)
2x2 and 3x3
Exit availability results
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Inferential statistical analysis indicated no significant differences
in the time taken to make the exit available due to seating
configuration or vertical projection.
2x2 and 3x3
Study 2:- Modification to operating handle
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Test facility was a Boeing 737 cabin simulator configured in either:
3x3 configuration or 2x2 configuration
Exit operating handle configured in either:
Retracted (conventional) mechanism or fixed (modified) mechanism
40 participants:
Tested individually.
Repeated and counterbalanced on handle type
This paper reports data from naïve participants only
Dependent variables;
Egress time and exit availability time
Handle mods
Exit handle modifications
Handle mods
Procedure
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Participants were greeted by a researcher trained and dressed
as cabin crew. After check-in, participants boarded the cabin
simulator.
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Each participant sat in the seat adjacent to the Type III exit.
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Participant was given a typical pre-flight safety briefing.
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In addition, participants received an in-depth individual briefing
on their emergency duties (i.e. checking outside, heavy hatch,
mode of operation).
Handle mods
Evacuations
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On completion of the safety briefing, passengers heard a
recording of engine noise, followed by an announcement from
the Captain to “Undo your seatbelts and get out!”

The cabin crew member then instructed the passenger to open
and move towards the Type III exit.

Throughout the evacuation, cabin crew used assertive, positive
and concise commands to encourage the passenger to move as
quickly as possible (Muir & Cobbett, 1996).
Handle mods
Results
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Data on evacuation times was extracted from video footage
recorded outside the Type III exit. A participant was deemed to
have evacuated when both feet were on the wing.
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Only the results from the first trial – with naïve participants - are
reported here.
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Data were available from a total of 40 evacuations – 10
evacuations within each condition.
Handle mods
Mean evacuation times ppn (in secs)
Handle modification
Total
Seating
configuration
Retracted
Modified
3x3
12.8
(sd 3.8)
12.3
(sd 3.1)
12.5
(sd 3.4)
2x2
15.4
(sd 4.2)
17.9
(sd 6.1)
16.7
(sd 5.2)
Total
14.1
(sd 4.1)
15.1
(sd 5.5)
Handle mods
Evacuation results
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Inferential statistical analysis showed that there were statistically
significant differences due to the seating configuration.
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Individual participants evacuated quicker in the 3x3 configuration
than the 2x2 configuration. This effect was unlikely to have
arisen by chance.
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There were no statistically significant differences in evacuation
times due to handle modification, and no interaction between
handle modification and seating configuration.
Handle mods
Mean exit availability times (in secs)
Handle modification
Total
Seating
configuration
Retracted
Modified
3x3
11.0
(sd 3.6)
10.3
(sd 2.9)
10.6
(sd 3.2)
2x2
13.3
(sd 2.8)
15.7
(sd 5.8)
14.5
(sd 4.6)
Total
12.1
(sd 3.4)
13.0
(sd 5.2)
Handle mods
Exit availability results
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Inferential statistical analysis showed that there were statistically
significant differences due to the seating configuration.
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Participants made the exit available more quickly in the 3x3
configuration than the 2x2 configuration. This effect was unlikely
to have arisen by chance.
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There were no statistically significant differences in exit
availability times due to handle modification, nor an interaction
between handle modification and seating configuration.
Handle mods
Study 3: - Type III hatch disposal
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Test facility - Boeing 737 cabin simulator in a 2x2 configuration.
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Type III exit hatch configured as either:
Conventional “plug” style hatch or “up and over” ADH
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80 participants, tested individually.
Three ‘stooge’ passengers around the exit row to add a degree
of pressure on participants to evacuate quickly.
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Dependent variable: egress times and exit availability times
Hatch disp
Type III exit hatch with ‘plug’ design
Hatch disp
Type III exit hatch with ADH mechanism
Hatch disp
Procedure
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Participants were greeted by a researcher trained and dressed
as cabin crew. After check-in, participants boarded the cabin
simulator.

Each participant sat in the seat adjacent to the Type III exit.

Participants were given a typical pre-flight safety briefing.

A minimal briefing was also provided to the passenger seated at
the Type III exit (Cobbett, Liston & Muir, 2001).
Hatch disp
Evacuations

On completion of the safety briefing, passengers heard a
recording of engine noise, followed by an announcement from
the Captain to “Undo your seatbelts and get out!”

The cabin crew member then instructed passengers to open and
move towards the Type III exit.

Throughout the evacuation, cabin crew used assertive, positive
and concise commands to encourage the passenger to move as
quickly as possible (Cobbett & Muir, 1996).
Hatch disp
Results

Data on evacuation times was extracted from video footage
recorded outside the Type III exit. The participant was deemed to
have evacuated when both feet were on the wing.
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Data were available from a total of 40 evacuations – 10
evacuations within each condition.
Hatch disp
Mean evacuation times ppn (in secs)
Exit design
Conventional ‘plug’ hatch
Modified ‘up and over’ ADH
13.5
(sd 4.0)
8.6
(sd 2.6)
Hatch disp
Evacuation results
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Inferential statistical analysis showed that there were statistically
significant differences between hatch designs.
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Participants evacuated significantly faster when the hatch had an
ADH mechanism than when it was a conventional ‘plug’ design.
This effect was unlikely to have arisen by chance.
Hatch disp
Mean exit availability times (in secs)
Exit design
Conventional ‘plug’ hatch
Modified ‘up and over’ ADH
12.2
(sd 4.3)
5.8
(sd 2.1)
Hatch disp
Exit availability results
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Inferential statistical analysis showed that there were statistically
significant differences between hatch designs.
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Participants made the exit available more quickly when the hatch
had an ADH mechanism than when it was a conventional ‘plug’
design. This effect was unlikely to have arisen by chance.
Hatch disp
Conclusions
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All results relate to preliminary experimental work, but raise
interesting issues regarding Type III exits in smaller airframes.
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Findings from the second study directly contradict results in first
study. With small groups, overall evac time in 2x2 configurations
were quicker. With individuals, 3x3 was quicker.
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It may be that for small groups, the shortened passageway
length in 2x2 configuration offset the lack of headroom.
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With individual tests, pax were already in exit row, therefore
headroom a more important factor.
Hatch des
Conclusions
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The modification to the operating handle had no effect on the
time taken to operate the exit, although this may be a function of
the in-depth exit briefing that was provided to passengers.
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However, there was an effect for configuration, such that
participants were able to make the exit available more quickly in
a 3x3 configuration. This again may be due to the additional
headroom available for the exit operator.
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ADH results replicate previous research on the up and over
mechanism in 3x3 configurations.