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Doomed plane on 'ghost flight'
15/08/2005 21:11 - (SA)
London - A sudden loss of cabin pressure could have caused temperatures aboard the Helios Airways flight to drop low enough to freeze passengers and crew, experts said on Monday.
But they said the decompression and a subsequent loss of breathable air are likely the main reasons why the pilots on board the Cypriot airliner were incapacitated, as reports suggest happened.
The Greek government has said the crews of two F-16 fighter jets that flew beside the Cypriot airliner before it went down saw its co-pilot slumped over the controls and its pilot missing from the cockpit.
Authorities said the cause of Sunday's crash appeared to be technical failure - resulting in high-altitude decompression. A transport official said the 115 passengers and six crew may have been dead when the plane went down in a mountainous region north of Athens. Temperatures down to -40°C
Some media have reported that the victims froze in their seats before the crash, but Greek officials said the bodies were not cold when they were found.
Chris Yates, an aviation analyst at Jane's Transport, said he was not surprised by suggestions that those on board the Helios flight may have frozen.
"At that sort of altitude, temperatures can be down to
-40°C to -50°C. At those temperatures, it doesn't take long to start freezing," he said.
Yates said it was likely that the aircraft "was flying essentially on a ghost flight for a chunk of its journey".
"The aircraft could have been flying itself for an hour, an hour-and-a-half while people were freezing to death."
David Kaminski Morrow, deputy news editor of the British-based air transport intelligence magazine, said any dramatic drop in temperature would likely have been caused by depressurisation.
The system that maintains cabin pressure and the system that keeps the cabin heated both rely on hot air passing through the engines. Any loss of pressurised air would also cause a drop in temperature, he said. Lack of oxygen
"If the cabin depressurised, you would be left with very thin oxygen inside the cabin, and thin oxygen at that altitude is very cold," Kaminski Morrow said.
He said a sudden decompression could have resulted from a window being blown out, or a fuselage rupture, resulting in pressurised, warm air rushing out of the aircraft.
But Kaminski Morrow said the loss of oxygen was likely the main reason that the pilots appeared to have been unable to control the aircraft, rather than the freezing temperatures.
"If you tried to breathe the outside air at cruising altitude, you would pass out through lack of oxygen very quickly, much faster than you would freeze," he said. "The cabin temperature is probably just a side effect of whatever has gone wrong."
In Greece, one official rejected media reports that bodies from the crash had been found frozen.
"The bodies that I saw were flexible. They were not frozen," said deputy fire chief Andreas Kois at the crash site.
Cypriot health minister Andreas Gavrielides, standing outside a morgue in Athens, said the black box from the flight and post-mortems on the victims would be needed to determine if the victims froze to death.
- AP
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