A recording of the last minutes before the 1998 crash of a Swissair plane into the sea near Halifax in Canada, in which 229 people died, has been released.
The tapes of the Swissair flight 111 accident – the worst in Canadian and Swiss aviation history - had been kept sealed since the crash.
The recording was released to the Canadian Press news agency following a court battle that went all the way to the Supreme Court of Canada. It was made public on Tuesday.
It includes the 12 last critical minutes, starting as the plane's crew reports smoke in the cockpit and ending with a last desperate transmission as the aircraft makes a high-speed nose dives into St Margaret's Bay, Nova Scotia, near Halifax. The aircraft was on its way from New York to Geneva.
The official transcripts do not indicate which of the two pilots are speaking.
"We are declaring an emergency now," one of the men says.
Their voices later become muffled as they don their oxygen masks.
Ten minutes later, smoke billows through the cockpit and a massive electrical failure disables all flight controls, including the lights. The transmission states: "We are starting to dump [fuel] and have to land immediately."
The MD-11 aircraft flew for about six more minutes before it slammed into the dark, choppy sea off Nova Scotia at 10.31pm local time.
Hitting the water at about 563km per hour everyone aboard died instantly and the fuselage shattered, due to the tremendous impact.
Audio first refused
Within days of the tragedy, the safety board released transcripts of the air traffic control recordings but refused to release the audio itself, saying it contained personal information.
An investigation by Canada's Transportation Safety Board blamed flammable insulation that allowed a small electrical fire to spread uncontrolled, melting the cockpit ceiling, shorting out all power and leaving the crew helpless to avert the disaster.
In October 1998, a month after the crash, Swissair paid 156 victims' families a total of SFr4.7 million. The following March, the airline paid each of the families SFr195,000. It also upgraded its safety measures.
Swissair never really recovered from the accident. The downturn in the aviation market after the terrorist attacks of September 11, 2001, proved the last straw for the heavily indebted national carrier, which folded the following year.
It had also over-extended itself by buying stakes in numerous loss-making airlines.
The remains of Swissair and the regional carrier Crossair were brought together in 2002 to form the new national carrier Swiss, which was in turn taken over by Germany's Lufthansa in 2005.
The release of the recording comes as eight employees of Swiss air traffic control agency Skyguide stand trial over a collision in 2002 over Lake Constance in which 71 people died.
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Swiss aviation accidents
The worst accident in Swiss civil aviation history occurred when a Swissair MD-11 jet went down off the coast of Canada in 1998. All 229 passengers and crew on board were killed.
In November 2001 a Crossair plane crashed on its final approach to Zurich with the loss of 24 lives.
Another disaster occurred in July 2002, when a Russian passenger jet collided with a DHL cargo plane in Swiss-controlled airspace, killing 71 people. Switzerland's air traffic control agency, Skyguide, was partially blamed for failing to prevent the collision.