The Most Complex of Aviation Safety Investigations
1.1 The Flying Coffin
The crash of Swissair 111 was not the result of a single failure. Immediately after the crash there was mounting speculation that a catastrophic electric failure aboard the seven-year old MD-11 was a likely culprit, however, as the investigation progressed it emerged that this was one of a number of factors that contributed to the crash. It should be noted that the ‘catastrophic electric failure’ encompasses five issues:
1. The specific wiring used aboard the aircraft.
2. The impact of maintenance practices on the aircraft’s wiring.
3. The aging characteristics of the aircraft’s wiring.
4. The configuration of the aircraft’s wiring.
5. The installation and certification of the aircraft’s In Flight Entertainment System (IFEN).
The catastrophic electric failure exacerbated other underlying shortcomings in the construction of the aircraft including the characteristics of the thermal acoustic insulation blankets (M-Pet) that lined the aircraft. After extensive flammability testing, the TSB determined that such blankets are ‘susceptible to being ignited by small ignition sources, such as electrical arcing or sparking and will propagate a fire’.
The crash also highlighted the inherent dangers in Swissair’s checklist procedures in the event of a smoke in the cockpit scenario and the widespread practice of resetting circuit breakers. Whilst the TSB was not able to ascertain the exact single cause of the crash, it did identify a number of safety deficiencies that contributed to it.
Although the TSB singled out insulation blankets as a major contributing factor, they also referred to arced wiring but could not state conclusively whether or not that wiring was associated with the in-flight entertainment system or other aircraft wiring. Given Kapton’s susceptibility to arcing, the question remains if the Kapton wiring arced independent of the in-flight entertainment system or vice versa.
Indeed, their findings identified safety deficiencies that have directly affected hundreds of other aircraft from around the world. In all the TSB issued four Aviation Safety Advisories, an Aviation Safety Information Letter and twenty-three Safety Recommendations. We have also detailed the failure of the FAA to act expeditiously with respect to Audio, Data and Video Recorders by way of example of the FAA’s apparent reluctance to implement recommendations in a timely manner or at all.
Early on Lyn referred to the MD-11 aircraft in question as a “Flying Coffin”. Although her comments were initially attributed to a widow’s anger, in time many others realized that her use of this term was anything but ill conceived. The term has become synonymous with the crash of Swissair Flight 111 and accurately reflects the host of issues that downed the aircraft.
1.2 Humanitarian Issues
From a non-technical perspective, IASA also confronted a number of humanitarian issues. These included the proposed recovery by Lloyds of London of cargo from the crash site, the extent of DNA identification of human remains recovered from the crash site, the practice of erecting monuments in the vicinity of aircraft crashes, the procedures associated with the identification and return of the victims personal belongings to family members and finally the provision of information to family members on the part of regulators and investigators.
 TSB Final Report. Section 18.104.22.168 Other Thermal Acoustic Insulation Materials at Risk.