1998 Crash Cost 229 Lives; On-Board Fire Blamed

Canada's Transportation Safety Board has released its final report on the September 2, 1998 crash of a Swissair MD-11, nicknamed "The UN Shuttle" because of that flight's popularity among members of that world organization.

There were no surprises in the final determination -- the plane's systems were compromised by an invisible fire, which quickly incapacitated those systems and some controls -- but the relief afforded by the release of the report, and the recommendations contained therein, will have long-lasting effects.

Even as MD-11s are accelerating toward airplane boneyards, lessons learned -- in wiring, in circuitry, in composition and placement of flammable materials -- are being implemented through the airline industry, and other industries, from architecture to automotive design.

Here's a synopsis of the causes:

1. Aircraft certification standards for material flammability were inadequate...
2. Metallized polyethylene terephthalate (MPET)–type cover material on the thermal acoustic insulation blankets used in the aircraft was flammable...
3. Once ignited, other types of thermal acoustic insulation cover materials exhibit flame propagation characteristics similar to MPET-covered insulation blankets and do not meet the proposed revised flammability test criteria...
4. Silicone elastomeric end caps, hook-and-loop fasteners, foams, adhesives, and thermal acoustic insulation splicing tapes contributed to the propagation and intensity of the fire.
5. The type of circuit breakers (CB) used in the aircraft were similar to those in general aircraft use, and were not capable of protecting against all types of wire arcing events...
6. A segment of in-flight entertainment network (IFEN) power supply unit cable (1-3791) exhibited a region of resolidified copper on one wire that was caused by an arcing event...
7. There were no built-in smoke and fire detection and suppression devices in the area where the fire started and propagated, nor were they required by regulation...
8. There was a reliance on sight and smell to detect and differentiate between odour or smoke from different potential sources. This reliance resulted in the misidentification of the initial odour...
9. There was no integrated in-flight firefighting plan in place for the accident aircraft, nor was such a plan required by regulation. Therefore, the aircraft crew did not have procedures or training directing them to aggressively attempt to locate and eliminate the source of the smoke...
10. ...The fire-related failure of silicone elastomeric end caps installed on air conditioning ducts resulted in the addition of a continuous supply of conditioned air that contributed to the propagation and intensity of the fire.
11. The loss of primary flight displays and lack of outside visual references forced the pilots to be reliant on the standby instruments for at least some portion of the last minutes of the flight. In the deteriorating cockpit environment, the positioning and small size of these instruments would have made it difficult for the pilots to transition to their use, and to continue to maintain the proper spatial orientation of the aircraft.

FMI: www.bst.gc.ca/en/reports/air/1998/a98h0003/a98h0003.asp