Thursday, August 12, 1999 Published at 04:52 GMT 05:52 UK
Insulation clue to Swissair crash
All on board the Swissair flight perished in the crash
Canadian investigators believe they have found one of the causes of the Swissair crash which killed 229 people off the coast of Canada last September.
The jet, an MD-11, was en route from New York to Geneva when it plunged into the Atlantic Ocean off the coast of Nova Scotia on 2 September, 1998.
The pilots had reported an unusual smell and smoke in the cockpit just minutes before they issued an emergency distress call to Canadian air-traffic controllers.
The investigators - who spent the last 11 months piecing together the final moments of Flight 111 - said cockpit insulation retrieved from the ocean floor revealed a significant amount of fire damage.
"While the source of the ignition has yet to be determined, there are indications that a significant source of the combustible materials that sustained the fire was thermal acoustical insulation blanket material," the safety board said.
The agency urgently recommended that all insulation blankets be tested for compliance with more rigorous fire standards.
Mylar failed tests
Soon after the Canadian announcement, the Federal Aviation Administration (FAA) in Washington said it would order US airline operators to replace metalised Mylar in 699 aircraft within the next four years.
It found Mylar fell far below fire resistance standards in a new test developed by the FAA.
FAA administrator Jane Garvey said: "We've weighed the benefit of replacing insulation, reviewed the service history of these aircraft and have made the right decision based on scientific data."
The planes involved were all made by McDonnell Douglas, now owned by Boeing. In addition to the MD-11, the aircraft affected are the DC-10, MD-80, MD-88 and MD-90.
McDonnell Douglas had recommended in 1997 that the insulation blankets be replaced on at least 1,000 jets.
More than half of the affected aircraft are operated by US carriers, including American Airlines, Delta Airlines, Continental Airlines and Trans World Airlines.
Another 531 of the affected aircraft are registered in other countries.
The FAA estimated the cost of the insulation replacement to the US operators at about $255m, or between $380,000 and $880,000 per plane. Airlines said the true cost had not been determined.
The BBC's Lee Carter in Toronto says shortcomings in Mylar's fire resistance had been raised by Swissair crash investigators some time ago, but this is the first time it has been officially confirmed.