AC-120-80: In-flight cockpit and cabin fires

Staying Legal

AC-120-80

In-flight cockpit and cabin fires

By Stephen P. Prentice

Stephen P. Prentice

Many of you may have received or seen a copy of this Advisory Circular dated Jan. 8, 2004. I am wondering if your impressions after reading it were the same as mine? In-flight fires are not common but they do occur with some regularity and usually with disastrous results. Although the AC was directed toward transport category passenger aircraft, the techniques described for detecting, locating, and extinguishing on-board fires are equally applicable to freighters, charter, and private aircraft as well.

Primary rule
The primary rule, however, when any in-flight fire is suspected, is to get the aircraft on the ground as soon as possible. The AC, in this writer’s opinion, spends an inordinate amount of time discussing such things as locating the source of the fire or smoke, gaining access to it, and effectively applying extinguishing agents to put out the fire. Not a bad program for trained fire-fighters but a heavy responsibility for flight attendants. Nonetheless, this step must be taken in many circumstances.

Accidents cited
A series of accidents were cited in the AC all dealing with McDonnell Douglas passenger transports from 1983 through 2000. Interestingly, all those cited were DC9 type models. It was noted that an Air Canada DC9 made an emergency landing at Cincinnati in 1983. The aircraft landed intact but 23 passengers were unable to evacuate and died in the fire. Smoke inhalation was the probable cause of death of these passengers. Smoke inhalation is usually what gets you in an otherwise survivable landing. Let me mention another accident where smoke inhalation was a significant factor.

DC3 in-flight fire
I have frequently mentioned the infamous Ricky Nelson DC3 accident as an example of an in-flight fire accident that should not have taken so many lives.

The aircraft was cruising at 6,000 feet on New Year’s Eve Dec. 31, 1985. It was headed to Dallas for a nightclub engagement with Nelson and his band of some 10 people. The passengers requested more heat in the cabin. The captain turned on the gas combustion heater in the rear storage area of the aircraft. It had been somewhat erratic and had been worked on recently. The fact that it would not light off was not surprising to the crew. The accident investigation later revealed that fuel was leaking from the heater into the lower fuselage.

Some wisps of smoke were first noticed by the passengers in the back near the aft baggage area where the heater was located. The captain was called back and he discharged a fire extinguisher into the general area where the smoke was located. He said later that he saw no flames. He returned to his seat and asked ATC for a vector to the nearest airport. This was Texarkana some 40 miles behind the aircraft. Seconds later the captain reported smoke in the cockpit and immediately started a decent to look for a place to make an emergency landing. He had no smoke goggles or O2 mask. He landed in a farmer’s field, gear down, and came to rest near a clump of trees after taking down a pole and some wires. He did a superb job. The aircraft landed intact, but soon burned.

The crew crawled out their respective side windows and fell to the ground. The co-pilot was barely conscious and the captain was in shock. One engine was still running! They both had breathed large amounts of smoke mixed with the fresh air they got from their open windows. The captain opened the rear passenger door, saw flames and no sign of life from the passengers.

The total elapsed time from the initial wisps of smoke to ground impact was estimated at 12 to 14 minutes. The crew survived. The passengers did not. Autopsies showed that they all died before the ship landed from toxic gases combined with the smoke from the fire. Simple smoke hoods may have saved lives.

This aircraft had many plastic and polyurethane products in the interior plush furnishings and appointments. When these burn they produce extremely toxic gases.

Air carrier aircraft today are permitted to have such plastic appointments installed in the interior notwithstanding their toxicity when burning. So you may survive the landing and be taken down by the toxic smoke while trying to get out, as was the case with the Air Canada aircraft mentioned previously. Fireblocking of polyurethane materials should be mandatory, keeping in mind the speed with which it reaches maximum toxicity when burning. Many newer products have superior fire-resistant and nontoxic qualities, though they are more expensive.

Technicians’ responsibility
Technicians have a duty to pay attention to the aircraft they inspect with regard to educating owners and operators on dangers involving fire-related accidents in both general aviation and air carrier aircraft. Particular attention should be directed at the materials used for seat covers, rugs, headliners, and wall panels. They all have to meet minimum FAR requirements and higher air carrier standards. Many private and some air carrier aircraft have substandard and or nonapproved interior components.

Any technician who approves aircraft for return to service should pay more than casual attention to new aircraft interior installations to see that they conform to requirements. The aircraft must be airworthy and the technician should review all the details of any interior installation.
Time is of the essence

We have to recognize of course that air carrier jets today will be flying at much higher altitudes than the DC3. It will take considerably longer to get down to a suitable landing surface. Needless to say, if over water, larger problems are present.

The AC also has an interesting chart that describes the time it takes for an in-flight fire emergency to become nonsurvivable. They cite seven examples from 1969 through 1998. These times range from seven to 35 minutes. Aircraft included are a Caravelle, B-707, DC9, B-747, and MD11. The report goes on to say that “. . . if the fire is a hidden fire, an approximate assessment is that only one-third will reach an airfield before the fire becomes uncontrollable.” Not a very comforting statistic. We all remember the ValuJet crash in Florida and cite it as another example where the crew lost control of the aircraft shortly after smoke entered the flight deck. This was a DC9, another Douglas aircraft. This accident is not mentioned in the AC however.

Since ETOPS requirements are 120 minutes to any landing from an over water emergency, the conclusion is obvious. Long overwater flights require well-trained fire response crews that can at least attempt to contain a fire.

Needless to say, the ability to locate and fight an in-flight fire is an important training issue. The AC highlights the important areas of concern. All crew members need to be clear on how to go about trying to locate the source without danger of expanding the problem.

The AC reviews briefly four accidents that the NTSB focused on. Again, it is interesting to note that the cited examples are all McDonnell Douglas aircraft.

Recent Canadian accident
A more interesting recent example is the Swissair MD11 that went down near Nova Scotia, Canada in 1998. The AC did not detail this accident but it is a recent example that was examined by Canadian authorities. You may have seen the recent TV report on public TV highlighting the Canadian report on the accident. The investigation by the Canadian Transport authority was most thorough, costly, and meticulous and finally found the reason for the fire. Wiring above the flight deck smoldered and caught fire. It was concluded that the crew was disabled by the smoke and lost control of an otherwise intact, flying aircraft. The consensus was that they had delayed too long in trying to troubleshoot the problem and lost the opportunity to put the aircraft down safely in the first few minutes of the emergency. Troubleshooting should be done on the ground not in the air. A similar scene was present for a different reason when an Alaska Airlines crew tried with the aid of ground maintenance to fix a stab trim problem in the air. The result was disaster.

Personal breathing units
For passengers, many observers have urged the placement of simple smoke hoods at each seat in passenger aircraft. They would take up no more room than the many telephone or TV installations and would be infinitely more useful. These relatively low-priced devices could save countless lives in many instances where it takes time to get out of a smoke-filled aircraft. They routinely provide protection for 15 to 20 minutes which could be life saving in many cases. Unfortunately, the AC does not mention these devices. Personally, I carry my own. Pick up a copy of the AC or read it on the web at: http://www.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/MainFrame?OpenFrameSet.
Send your comments to aerolaw@att.net.

Stephen P. Prentice is an attorney whose practice involves FAA-NTSB issues. He has an Airframe and Powerplant certificate and is an ATP rated pilot. E-mail: aerolaw@att.net

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