Re: Emergency exits capacity

From:         D.P.Rhodes@lut.ac.uk (Darren Rhodes)
Organization: Loughborough University
Date:         12 Sep 95 20:18:54 
References:   1
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In article <airliners.1995.1437@ohare.Chicago.COM>
Jean-Francois Mezei <mezei_jf@eisner.decus.org> wrote:
> I have a few question on emergency exits for airplanes :
>
> Is the "must be able to empty plane in 90 seconds" a real requirement or just
> urban legend ?

All planes must meet this requirement. There are strict regulations on people
used for such activities:

>From JAR 25.801

At least 30 percent female

At least 5 percent over 60 years old

At least 5 percent but not more than 10 percent must be children, prorated
through that age group.

Three life-size dolls, not included in the passenger total, must be carried by
passeners to simulate live infants 2 years old or younger.

No person can used that has taken part in one less than 6 moths previous. Also
no airport/airline related staff may be used as passengers. The test must be
carried out at night or in a darkened room to simulate night. Seat belts must
be fastened. Approx. one-half of the typical hand baggage load must be
scattered around the cabin. Not more than 50 percent of the emergency exits
must be used. Etc...

> Are there specific and widely accepted ways to measure each exit's capacity in
> an emergency ? If so, what are the criteria used ? (door size, chute length,
> cabin/aisle design ?) Or do aircraft manufacturers actually load up a plane
> with people and make the test ?

Doors are categorized according to size. Briefly:

Type A: not less than 42 inches by 72 inches.
Type I: Not less than 24 inches by 48 inches.
Type II: Not less than 20 inches by 44 inches.
Type III: Not less than 20 inches by 36 inches.
Type IV: Not less than 19 inches by 26 inches.
Ventral: Must be type I size.

Chutes must long enough so that they touch the ground should undercarriage
collapse occur. They must inflate in 10 seconds and withstand a 25kt cross
wind. All exits over 6ft from the ground must have chutes.

Yes the manufactures load the planes up to make the test. I believe the exact
rules have changed recently, after a person was paralysed after slipping at
the top of the slide and breaking their neck. They now simply evacuate into a
room and extra time is added.

> Does anyone have specific numbers on how many passengers a full fledged door
> (with chute) can process (per minute ?) and how over-wing exits fair in that
> regard ?

A pair of type A doors allows 110 people to be evcuated in 90 seconds.

> If the "90 seconds" requirement is true, does it apply to a plane with all of
> its doors usable, or does it assume that a certain percentage of its doors will
> be unusable ?

See above!

Number of exits is:

                Type 1  Type II Type III  Type IV

1  to 9                                       1
10 to 19                            1
20 to 39                    1       1
40 to 79           1                1
80 to 109          1                2
110 to 139         2                1
140 to 179         2                2

Over 179 people the follwing one pair of the following type gives extra pax:

Type A          110
Type I          45
Type II         40
Type IV         35

Over 299 only Type A and Type I doors can used.

Hope that answers all your questions!!!
--
Mr. Darren P. Rhodes        | Dept. of Aeronautical & Automotive Engineering
tel: [+44] 01509 223454     | & Transport Studies
fax: [+44] 01509 267613     | Loughborough University of Technology
email: D.P.Rhodes@lut.ac.uk | Loughborough, Leics., England, LE11 3TU