Brann ombord - Curt Lewis

INFLIGHT FIRE

By Captain Shem Malmquist

• June 2, 1983, Air Canada flight 797 experienced an in-flight fire.  The first hint of smoke odor occurred at 1900 CDT.  The crew had thought they had extinguished the fire.  At 1907 CDT the smell of smoke returned, and just two minutes later aircraft electrical systems began to fail.  The flight crew was able to get the aircraft on the ground, landing just 13 minutes later.  90 seconds later the fire flashed over, killing 23 passengers.
• February 7, 2006, a UPS DC-8 crew detected a faint odor that smelled like burning wood as they descended from FL330  enroute to Philadelphia.  25 minutes later they touched down on 27R at PHL.  The crew stopped the aircraft and the cockpit filled with smoke.  The crew evacuated and the aircraft subsequently became engulfed in flames.
• September 5, 1996, a FedEx DC-10 crew responded to  in-flight smoke.  Landing just 18 minutes later inNewburgh, New York, the crew and jumpseaters evacuated the aircraft.  The aircraft was destroyed by fire.
• September 2, 1998, just barely over two years later, a Swissair MD-11 crashed less than 21 minutes after the pilots first noticed an unusual odor in the cockpit.
• September 3, 2010, a UPS 747-400 crashed while attempting to land in Dubai, UAE.   The flight was approximately 120 miles west of Dubai when the crew first declared an emergency.

As with any other emergency, surviving an in-flight fire requires sound procedures and regular training to ensure we, the flight crew, follows those procedures.  Unfortunately, a fire is one emergency that can kill you even if you do everything right, as the resources traditionally available to us have significant limitations.

Pilots are paid to manage risk.  The procedures flying a passenger aircraft are limited by such factors as passenger oxygen.  Cargo aircraft have a different set of concerns. Regardless of whether you fly passenger or cargo aircraft, knowing what tools are out there is worthwhile. Consider, for example, the procedures to depressurize the aircraft to an altitude as determined by the manufacturer, a standard part of the checklist for cargo aircraft.  FAA tested this procedure and found that:

... test results showed a reduced burn rate for all materials tested as the altitude increased (pressure decreased). The decreased burn rate was nearly linear, slightly greater than a reduced rate of 2% per 1000 feet. Testing of lithium metal and lithium ion batteries, a fire safety area of concern for all transportation modes, showed that altitude had little or no effect on the reaction. However, the time needed to heat the batteries to the point of reaction was increased, because of the reduced burn rate of the fuel supplying the heat, as altitude was increased (pressure reduced).

... test results showed that although depressurization reduced the initial burning, the fire intensity on decent was greatly accelerated. The highest depressurization altitude evaluated (25,000 feet) produced the best initial results but the largest fire on decent.[i]

 Absent a better solution, depressurization provides one of the best known methods to buy us time, but that must be balanced against the needs of passengers.  This is a decision only you can make.  Time is what we need to get on the ground.  Knowledge of the research, however, might provide some clues as to how and when you might want to plan your descent in the event of a fire.

Unfortunately, one of the greatest threats today is the carriage of Lithium batteries and current systems provide at best limited protection for Lithium fires.  A study published by the Royal Aeronautical Society found that:

On a typical flight, a single aisle jet carrying 100 passengers could have over 500
lithium batteries on board. These devices are not tested or certified nor are they
necessarily maintained to manufacture's recommendations. Replacement batteries from questionable sources ('grey' market) can be contained within devices. ii

While the fact that a fire might be caused by Lithium batteries does not change most of the recommendations, it can force a situation where the ONLY option is an immediate landing or ditching.  It should also be noted that in certain circumstances the fire is associated with what is known as a "pressure pulse".  Essentially, a rapid combustion in an enclosed compartment or container builds up pressure like a bomb and when the walls of that enclosure breach a pressure wave is generated.  It is also possible to generate a pressure wave inside the aircraft just through a very rapid combustion.  Either way, this pressure pulse can then lead to the failure of the aircraft compartment.  As an example, if the fire is in a lower cargo compartment, the protection from the extinguishing agent is predicated on the walls of the compartment maintaining a relatively high concentration of the agent.  If a pressure pulse is able to compromise the containment of the extinguishing agent then all of the assumptions for keeping the fire under control are no longer valid.  Unfortunately, the cargo compartments were not designed to withstand even a fairly small pressure pulse.  It is not clear whether the flight crew would be aware of such an occurrence, although it is possible.

Each situation is different, and only the flight crew will be able to determine the best course of action.  With that stated, following are offered for your consideration.

Are you prepared should you encounter a fire?

There are things that we, as pilots, can do that will significantly improve our odds of surviving an in-flight fire.  The first thing to remember is that it is essential that you follow our training as closely as possible.  It is particularly vital that you become familiar with and follow the checklists in your aircraft as closely as possible.  A real fire is not the time to be fumbling with the checklist due to unfamiliarity.  Following all the procedures is great, but that does not mean that we cannot learn additional things to make the most of our procedures, such as the lesson above from the FAA studies of the effects of depressurization on fire.  Remember the procedures are based on assumptions that are only valid if the assumptions are true.

Reading through the brief synopsis list above, a common theme is how little time we have to respond to an in-flight fire.  A Canadian Transport Safety Board study found that your chances of surviving an in-flight fire decrease significantly after about 20 minutes, dropping to a very low probability after 35 minutes.

The following chart depicts the time that various crews had from the first indication of the presence of a hidden fire, to the time that fire became catastrophically uncontrollable[iii]:

DATE	LOCATION	AIRCRAFT TYPE	TIME TO BECOME NON-SURVIVABLE (MINUTES)
07-26-1969	BISKRA, ALGERIA	CARAVELLE	26
07-11-1973	PARIS,FRANCE	B-707	7
11-03-1973	BOSTON, USA	B-707	35
11-26-1979	JEDDAH,SAUDIA ARABIA	B-707	17
06-02-1983	CINCINATTI,USA	DC-9	19
11-28-1987	MAURITIUS,INDIAN OCEAN	B-747	19
09-02-1998	NOVA SCOTIA,CANADA	MD-11	16

 

A fire onboard an aircraft creates numerous hazards.  Here are some things to consider:

• At the first indication of a fire, it is vital that we don our full-face mask.   What is the first indication?  Often it is just the smell of smoke or fumes.