WASHINGTON -- The National Transportation Safety Board said Tuesday it could not determine the origin of a fire that killed 23 passengers on an Air Canada flight last year, but said the severity of the accident was increased by the flight crew's delayed decision to descend.
The accident occurred June 2, 1983, as Air Canada Flight 797 - bound from Dallas to Toronto -- flew over Kentucky. Twenty-three of the 46 passengers died after the plane landed,unable to escape the toxic smoke from burning plastic in the cabin.
The safety board said the delayed descent ate up precious minutes and prevented the plane from landing at Louisville instead of Cincinnati. Investigators said a Louisville landing would have put the plane on the ground three to five minutes earlier, presumably enough time to save some lives.
The three-member panel also said the flight crew's failure to realize the severity of the fire and to give the airplane captain correct information about the fire's progress contributed to the accident.
The board said there was not enough evidence to determine the cause of the fire, which began in a rear bathroom, although some investigators strongly suspected the blaze was electrical in nature.
'The National Transportation Safety Board determines that the probable causes of the accident were a fire of undetermined origin, an underestimate of fire severity, and conflicting fire progress information provided to the captain,' NTSB Chairman Jim Burnett said.
'Contributing to the severity of the accident was the flight crew's delayed decision to institute an emergency descent.'
Instead of immediately descending, investigators said the flight crew mistakenly tried to determine the extent of the fire and extinguish it, even though smoke and heat made it difficult to do so.
They also said members of the flight crew at one point told the captain the fire was under control, only to realize later they were in error.
'They perhaps should have realized they had no reason to be optimistic about the propogation of the fire or their efforts to control it,' said William Laynor, director of the NTSB's Bureau of Technology.
Air Canada spokesman Esther Szynkarsky defended the plane's crew as did the Air Line Pilots Association, which accused the NTSB of second-guessing the harried crew.
'The flight deck crew had just scant minutes to troubleshoot a condition that had never before occurred and for which they had no training,' said ALPA President Henry Duffy.
'Even so, the pilots performed superbly in bringing the crippled airliner to a safe landing despite the loss of most of their flight instruments.'
The Air Canada captain and co-pilot were honored by their peers last year when the received the ALPA superior airmanship award for bringing their stricken aircraft to a landing.
Some board members and NTSB investigators also criticized Captain Don Cameron for turning off the plane's air conditioning and pressurization units in an effort to cut the flow of oxygen to the fire.
They said the two systems were the best way to ventiliate the plane, which quickly filled with smoke during the accident.
'We lost two whole circulations of air,' said William Hendricks, chief of the NTSB's Air Accident Division.