The crash of a jetliner in Newfoundland three years ago that killed 256 U.S. soldiers and crew members resulted in part from the exhaustion of the flight crew, who ignored ice on the plane's wings, according to a preliminary Canadian report.
A still-unreleased draft report by the Canadian Aviation Safety Board noted that the crew had flown a grueling schedule in the two weeks before the accident. Had they finished the trip, the captain would have been awake 24 hours.
"I think these people were tired," Dr. Stanley Mohler said. "They had been on a series of flights prior to that, which were fatiguing. I just think they needed a good night of sleep."
Mohler, head of aerospace medicine at Wright State University in Dayton, Ohio, advised the Canadian board on fatigue factors in the crash.
The plane, an Arrow Air charter, crashed Dec. 12, 1985, while taking off from a refueling stop at Gander International Airport, killing everyone aboard. The plane was ferrying U.S. troops from peace-keeping duties in the Sinai peninsula to Ft. Campbell in Kentucky.
The preliminary report lists ice on the wings of the plane as the principal cause of the crash. But it says that a too-slow takeoff speed and flight-crew fatigue were contributing factors.
Spokesman James Harris said the board hopes to release a final version of the report in early December.
"It may bear no similarity to the draft report," he said. "In fact, it won't. It will be quite different."
He said he did not know whether fatigue would still be listed as a contributing cause.
The draft report said that twice in the two weeks before the crash, the crew had flown longer than allowed by U.S. regulations. According to federal rules, no crew member may be on duty aloft for more than 12 hours in any 24-hour period.
If the flight had made it to Oakland, Calif., its final planned stop, the crew would have flown about 15 hours and been on duty for 20. However, because the plane would have carried no passengers on its final leg, this trip would not have violated federal limits.
The board could not determine with certainty whether the pilot, co-pilot or flight engineer were truly fatigued. However, it cited Mohler's testimony that "in the 12 days leading up to the accident, the flight crew had been consistently exposed to work patterns and fatigue-producing factors which were highly conducive to the development of chronic fatigue."
These included short layovers, night departures, multiple time-zone crossings and almost 57 hours in the air in the previous 10 days.
In one 48-hour period that month, the crew flew for more than 22 hours, then were back in the cockpit seven hours later.
The report said that at Gander the crew members failed to notice ice on the wings, which prevented the plane from gaining altitude after it lifted off, and they set the wrong takeoff speed.
"Each of those would be consistent with tired pilots," Mohler said. "Tired pilots do things like that. They omit things. They make mistakes."