How Things Work: Evacuation Slides
De-plane in the fast lane.
- By Mark Huber
- Air & Space magazine, November 2007
From the door and emergency exits of a China Eastern Airlines Airbus A330-300, evacuation slides are deployed. The fully inflated slide is 31 feet long. Yusu Ren
THE POST-CRASH FIRE THAT CONSUMED Air France Flight 358, an Airbus A340 that overran a Toronto runway in 2005, could have been a killer, but all 309 aboard escaped with no life-threatening injuries. By the time emergency response teams had arrived, 52 seconds after the airliner burst into flames, most of the passengers had already exited on evacuation slides.
The Airbus met almost to the letter the Federal Aviation Administration requirement that an airliner be capable of being evacuated within 90 seconds in the dark and with half the exits blocked—“almost” to the letter because the crash occurred not in the dark but on an August afternoon. But the evacuation was successful even though several exits were compromised by the fire and jagged metal and one slide was inoperable, apparently jarred loose when the airliner plunged into a ravine.
Designing evacuation slides has grown more complex as the FAA has tightened performance standards. In the early 1960s, slides had to deploy in 25 seconds in non-extreme weather: no wind and medium-range temperatures. Today’s slides must deploy in six seconds in temperatures ranging from –65 to 160 degrees Fahrenheit and unfurl in winds up to 25 knots (28.7 mph). Airlines impose further challenges: Slides must be light and compact enough to fit inside an aircraft door or below the door sill or emergency exit window. So each slide is uniquely developed for its location on an aircraft model.
An escape slide sits inside a carbon fiber pressure cap covered by a casing of material similar to the aircraft interior walls—that big square box at the bottom of an airliner’s interior door. Pushing a lever on the interior door—a large silver bar on early airliner models, smaller handles on later ones—arms the slide mechanism by linking the slide to the door sill. When the lever is in the “armed” position, opening the door pulls the slide out of its pack. The slide then drops to the correct orientation for inflation to begin. (When flight attendants issue the call to “cross-check” after landing, that is a signal for one attendant to check another’s action to disarm the doors to prevent slides from inadvertently deploying.)
Slides inflate with an initial boost from a canister of compressed carbon dioxide and nitrogen. The canister provides only about one-third the volume needed to inflate the slides. The remaining volume is supplied by ambient air, channeled into the slides through aspirators.
When the inflation mechanism is triggered—by a lanyard pulled by the slide as it tumbles from its storage case—gas from the canister accelerates through the aspirators at high speed, creating a vacuum that sucks ambient air into the aspirators through louvers. When the slide is fully inflated, the louvers close.
At its Phoenix, Arizona plant, Goodrich manufactures airliner evacuation slides for a number of airliner models, including the 16 slides aboard each giant Airbus A380. To get the A380 slides fully inflated in six seconds, Goodrich developed an inflator that uses a gas generator about the size of a soda can that contributes more inflation gas volume to the slides without adding too much bulk and weight to the slide package. When a propellant in the generator is ignited, it produces a highly compressed gas almost instantly. This gas mixes with stored gas in the canister to accelerate slide inflation.
Slides are made of urethane-coated nylon that is sprayed with gray aluminized paint, which protects the slide in case of a nearby fire by reflecting heat for at least the 90 seconds of the slide’s use. To save pack weight and decrease inflation time for the A380 and new-generation aircraft to follow, Goodrich adopted a stronger fiber for the inflation tube fabric. Increasing the strength and tear resistance of the fabric enables slide inflation tubes to be designed with a smaller diameter.
Related topics: Aerospace Science Airliners and airfreight carriers Modern Aviation
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Comments (6)
as an aid to project research could you please advise:
* how many injuries have been sustained using emergency aircraft evacuation slides
* what safety devices are required at bottom of slide in simulation exercises
Thankyou for your help
Posted by kath kinder on June 22,2008 | 08:36 AM
Kath in response to your questions....
and for your info I am a flight attendant for a British Airline.
1. The total amount of injuries sustained following an evacuation is difficult to calculate as there are so many factors that will ultimately affect the evacuation itself.
The more common injuries will be friction burns as people instinctively grab onto the sides of the evacuation slide when descending in an attempt to slow down their egress speed. Also friction burns will occur if the individual is wearing man made fibre clothing (always wear cotton underwear when flying!!)and also sprains, strains etc will occur as the impact at the botttom of the slide is quite sudden and deccelaration is also very quick, and if there is a build up of people trying to get off the slide this can also contribute to possible injuries.
2. In a simulated evacuation using real inflatable slides on or off an aircraft the safety devices required are crash mats ie padded mats at the bottom of the slide, similat to what gymnasts use, and isf the slide is a training one ie in a purpose built building there may be extensive "padding" in the area of the slide incase of someone falling over the side of the slide or coming off the bottom with such momentum they might collide with something. Also in a Training facility the event is usually
videotaped/filmed so that a.)Feedback on evacuation techniques can be reviewed and discussed and b.) In case any delegate suffers injury so that the incident can be reviewed to see if the correct procedures were adhered to.
Hope that has given you some information.
Pls contact me if you need any more
Regards Stuart.
Posted by Stu Jamieson on July 7,2008 | 12:36 PM
From I understanding that two manufactures in USA make the evaculation slide for aircafts. They are : Air Cruiser and
Goodrich. Do these manufactures also make the evaculation slide for training equipments of the flight attendents traing center? Is there any other manufactures in North American region can make the same products other than these two companies?
Thanks a lot.
Posted by William Jin on September 1,2008 | 04:50 AM
May i know the size of evacuation slide/fully inflated for aircraft model A320? EDITORS' REPLY: You would need to contact Airbus.
Posted by Avet Palanog on March 15,2010 | 05:23 AM
Airbus 380 Does not meet FAA regulations for safety- No one in the F.A.A. would sign it off, The last (Retired now) Administrator had to do the honors and quietly left for safer places, The puplic is political fodder waiting to find a cannon. Kick the tires and light the fires folks--it's Mr. Toad's wild ride.
Posted by Don Hillberg on October 29,2010 | 12:50 AM
Very easy to inspect and pack the ones we use on the KC-135R. I'd hate to be hit by one inflating out the aft hatch.
Posted by Darin on May 27,2011 | 10:42 PM