TSB # A01/2003
Transportation Safety Board of Canada Releases Final
on Swissair 111, Accident Investigation
Report # A98H0003
Makes Nine Additional Safety Recommendations, Bringing Total to 23
(Halifax, Nova Scotia, 27 March 2003) – The Transportation Safety Board of Canada (TSB) today released its final report on the investigation of Swissair Flight 111 (SR 111), which crashed off the coast of Peggy's Cove, Nova Scotia, on 2 September 1998. All 229 people on board perished.
The report identifies the causes and contributing factors that played a major role in the occurrence, reviews the 14 Aviation Safety Recommendations that have already emerged from the TSB investigation and the impact those recommendations have already had on aviation safety, and makes nine additional Aviation Safety Recommendations.The nine additional Aviation Safety Recommendations in the final report, include:
- Two Aviation Safety Recommendations that deal with testing and flammability standards of in-service thermal acoustical insulation materials and one that deals with the application of existing standards for the certification of other materials.
- Two Aviation Safety Recommendations that focus on aircraft electrical systems, including additional measures for certifying supplementary add-on systems and industry standards for circuit breaker resetting.
- Four Aviation Safety Recommendations that propose improvements to the capture and storage of flight data as it relates to cockpit voice recorders, flight data recorders, and cockpit image recording systems.
"This has been the largest, most complex aviation safety investigation the TSB has ever undertaken, and required a significant investment of people, resources and time," said Camille Thériault, Chairman of the Transportation Safety Board. "The efforts of thousands of hardworking people from various countries, industries and regulatory authorities have culminated in a comprehensive report that has changed the face of aviation safety."
The report explains that, at a point along the flight route of SR 111, a failure event occurred that provided an ignition source to flammable materials in the aircraft. This set off an in-flight fire that spread and increased in intensity until it led to the loss of the aircraft and human life.
The SR 111 investigation involved prolonged wreckage recovery operations before technical issues could be addressed. Through detailed examination, reconstruction and analysis of recovered material, the TSB developed potential fire scenarios and identified how and when flammable materials were ignited and how the fire propagated.
Causes and Contributing Factors
The report notes that the fire most likely started with an electrical arcing event involving one or more wires. The arcing event ignited the metallized polyethylene terephthalate (MPET) covering material on the thermal acoustical insulation blankets above the right rear cockpit ceiling of the McDonnell Douglas MD-11 aircraft.
A segment of the in-flight entertainment network (IFEN) wiring from that area exhibited a region where copper had resolidified, indicating an arcing event. TSB investigators believe that this arcing event on the entertainment system wire was associated with the initial arcing events. However, investigators could not pinpoint this as the lead event, as other wires from that immediate area could not be identified. The circuit breakers in the aircraft were not capable of protecting the wiring against the type of arcing event that occurred.
Aircraft certification standards for material flammability at the time of the SR 111 accident were inadequate, allowing materials to be used in aircraft construction and modification that could ignite, and sustain or propagate a fire. Once ignited, other types of thermal acoustical insulation material with similar flammability characteristics may have contributed to the propagation of the fire.
There were no smoke/fire detection and suppression devices in the area where the fire started, nor did regulations at the time require them. Therefore, the flight crew had very few resources, other than sight and smell, to detect and differentiate between the source of the odours and smoke. The delay in identifying the existence and source of a fire allowed the fire to propagate until it became uncontrollable.
An integrated firefighting plan was not required by regulation. As a result, the flight crew did not have appropriate tools, procedures, or training to locate and eliminate the source of the smoke in a hidden area. For some considerable time, they were not aware of the existence of the fire, or for the need to prepare rapidly for an emergency landing.
In this occurrence, the failure of silicone elastomeric end caps on air conditioning ducts resulted in a continuous supply of conditioned air initially into the space above the forward cabin and then above the cockpit ceiling area. These failures and the flammability of some other materials contributed to the rapid propagation and intensity of the fire.
As conditions deteriorated in the cockpit, the flight crew lost the use of primary flight displays and outside visual references. The heat, smoke and fumes inside the cockpit made it increasingly difficult for pilots to maintain the proper spatial orientation of the aircraft, resulting in a collision with water.
"We have already seen profound results stemming from this investigation. That is because we acted immediately to inform the aviation community about safety deficiencies as soon as they were identified," said Mr. Thériault. "Our focus is—and always has been—to put our key findings to use as soon as they become known to us, to improve aviation safety."
The TSB's comprehensive approach to the investigation enabled it to identify important safety deficiencies related to a wide range of issues. These have been addressed in a series of Aviation Safety Recommendations (ASRs), Aviation Safety Advisories (ASAs), and Aviation Safety Information Letters (ASILs), which have been issued by the Board since the start of the investigation.
- In December 1998, an Aviation Safety Advisory, regarding wiring issues, was sent to the U.S. National Transportation Safety Board (NTSB). The NTSB then made a recommendation to the Federal Aviation Administration (FAA) requiring an inspection of all MD-11 aircraft for wiring discrepancies.
- In March 1999, four Aviation Safety Recommendations were issued regarding flight recorder duration and electrical power supply.
- In August 1999, two Aviation Safety Recommendations were issued regarding thermal acoustical insulation materials and flammability test criteria.
- In March 2000 and December 2000, an Aviation Safety Advisory and an Aviation Safety Information Letter, respectively, were issued regarding concerns about deficiencies in the design and installation of flight crew reading lights.
- In December 2000, five Aviation Safety Recommendations were issued regarding regulatory standards for in-flight firefighting.
- In August 2001, an Aviation Safety Advisory was issued regarding air traffic controller training with respect to emergency procedures.
- In August 2001, three Aviation Safety Recommendations were issued regarding deficiencies in aircraft materials flammability standards, including one dealing with the testing of wire failure characteristics.
- In September 2001, an Aviation Safety Advisory was issued concerning the need to review the regulatory requirements for standby (secondary) instruments.
Action has been taken by various regulatory authorities and others to address the recommendations, advisories and observations made by the TSB during the course of this investigation, significantly improving aviation safety worldwide. Several of these recommendations have already been adopted by regulatory authorities, airlines and aircraft manufacturers. For example, flight crew reading lights have been re-designed; the IFEN system was removed voluntarily from Swissair aircraft, and subsequently that design was de-certified.
New FAA policies are in place for the certification of such entertainment systems. The MPET insulation used on thermal acoustical insulation blankets was ordered removed from aircraft.
Flammability standards for materials used in aircraft are being upgraded. In-flight firefighting procedures have been subjected to intense review. Other safety measures stemming from TSB recommendations are currently being implemented.
The TSB also identified in the final report some safety concerns that require additional follow-up. The TSB will continue to work with regulatory authorities and the aviation industry to help ensure that the recommended safety improvements are carried out as effectively as possible.
The accident victims' families were briefed earlier today about the content of the SR 111 report. In the coming weeks, representatives from the TSB, including investigators and Mr. Thériault, will travel to cities in the United States and Europe for in-person meetings with those families wishing to attend.
On 2 September 1998, SR 111 departed John F. Kennedy Airport, New York, with 215 passengers and 14 crew members on board on a scheduled flight for Geneva, Switzerland. Less than an hour after departure, the flight crew noted an abnormal odour in the cockpit and assessed that smoke was present. They decided to divert, ultimately selecting Halifax International Airport as their destination. About 13 minutes after the flight crew detected an unusual odour in the cockpit, SR 111 experienced a rapid succession of aircraft system failures. The flight crew declared an emergency and indicated the need to land immediately. About one minute later, radio communications and secondary radar contact with the aircraft were lost, and the flight recorders stopped functioning. About five and one-half minutes later, the aircraft crashed into the ocean southwest of Peggy's Cove, Nova Scotia. The aircraft was destroyed and there were no survivors.
The Transportation Safety Board of Canada is an independent agency, operating under its own Act of Parliament. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.
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For additional information, see the following documents:
- Chairman's Speech
- TSB Background and Fact Sheet
- SR111 Investigation Chronology
- SR111 Executive Summary
- Summary of Safety Action Taken
The TSB is an independent agency that investigates marine, pipeline, railway and aviation transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.
For more information, contact:
Transportation Safety Board of Canada
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