Communiqués

Investigation Update Swissair Flight 111 - August 1999

(Halifax, Nova Scotia, 27 August 1999) - The Transportation Safety Board of Canada (TSB) investigation into the accident involving Swissair Flight 111 is continuing. Between early May and the end of July, aircraft wreckage was recovered by the research vessel Canadian Forces Auxiliary Vessel (CFAV) "ENDEAVOUR", working together with a remotely operated vehicle (ROV). This operation brought to the surface about 5,100 lbs of wire, portions of the aircraft skin and interior pieces. Some of the recovered pieces were from the forward ceiling area, and showed heat damage. The CFAV "ENDEAVOUR" was also involved in mapping and preparing the bottom area for the next recovery operation.

A final phase of recovery operations, planned for the middle of September, will employ a suction dredge ship for about a week. The recovered material will be transferred to an on-shore containment area to be sifted and sorted. It will likely take up to eight weeks to sift through the dredged materials. Retrieved wreckage items will then be taken to the investigation hangar at Shearwater, Nova Scotia, for identification and processing.

Tests are under way to assess the significance of the arcing found on 14 segments of wire from the accident aircraft. The TSB, in conjunction with a number of engineering laboratories, is working to develop a method to test whether the wires arced as a result of a short circuit in a normal environment or whether, instead, the arcing was a secondary outcome of a fire that damaged the wire insulation, which in turn allowed the wiring to arc. If a suitable test can be developed, the TSB will test some of the wire that has been recovered from the wreckage of Flight 111.

To date, the TSB has promulgated a Safety Advisory and six interim Safety Recommendations resulting from the investigation into this occurrence:

• a Safety Advisory concerning inspection of the wiring in the forward ceiling areas of MD-11 aircraft.
• four Safety Recommendations concerning flight recorders, dealing with independent power supplies and duration of CVR recordings.
• two Safety Recommendations dealing with the mitigation of risks associated with the flammability characteristics of certain types of thermal acoustical blanket materials, and the need to develop more rigorous test criteria for thermal acoustic blankets for use on aircraft.

The investigation into this occurrence is complex and time-consuming. Work is progressing at an appropriate rate for an accident of this complexity. More fact-finding and safety analysis will be undertaken as the investigation progresses over the coming months. This investigation has already led to the identification of safety deficiencies; should other deficiencies be identified, further safety action will be taken. At Hangar "A" in Shearwater, investigation progresses both on the analysis of aircraft components, and with the time-consuming reconstruction of portions of the first nine metres of the forward section of the aircraft. Work continues on the identification, examination, heat-damage analysis, and documentation and matching of aircraft front section pieces and recovered wiring. Aircraft maintenance records continue to be reviewed to seek trends or patterns that might assist in the ongoing investigation. Analysis is also continuing into which of the various electrically driven systems, such as the fuel pumps, were or were not functioning at the time of impact.

-(30)-