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

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.

Relatively little is known about whether the research findings generalise to a 2x2 configuration.

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

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.

Seats for each group were pre-allocated according to a random seating plan.

Each group of 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).

2x2 and 3x3

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, 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

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.

Data were available from a total of 24 evacuations – six trials within each condition.

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

Inferential statistical analysis showed that there were statistically significant differences due to the seating configuration.

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.

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

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 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

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.

Participant was given a typical pre-flight safety briefing.

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

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

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.

Only the results from the first trial – with naïve participants - are reported here.

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

Inferential statistical analysis showed that there were statistically significant differences due to the seating configuration.

Individual participants evacuated quicker in the 3x3 configuration than the 2x2 configuration. This effect was unlikely to have arisen by chance.

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

Inferential statistical analysis showed that there were statistically significant differences due to the seating configuration.

Participants made the exit available more quickly in the 3x3 configuration than the 2x2 configuration. This effect was unlikely to have arisen by chance.

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

Test facility - Boeing 737 cabin simulator in a 2x2 configuration.

Type III exit hatch configured as either: Conventional “plug” style hatch or “up and over” ADH

80 participants, tested individually. Three ‘stooge’ passengers around the exit row to add a degree

of pressure on participants to evacuate quickly.

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

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.

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

Inferential statistical analysis showed that there were statistically significant differences between hatch designs.

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

Inferential statistical analysis showed that there were statistically significant differences between hatch designs.

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

All results relate to preliminary experimental work, but raise interesting issues regarding Type III exits in smaller airframes.

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.

It may be that for small groups, the shortened passageway length in 2x2 configuration offset the lack of headroom.

With individual tests, pax were already in exit row, therefore headroom a more important factor.

Hatch des

Conclusions

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.

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.

ADH results replicate previous research on the up and over mechanism in 3x3 configurations.