The pilots of Northwest Flight 188 assert they lost track of time and location--but never went to sleep--when they failed last week to respond to air-traffic controllers for more than an hour, according to people familiar with what the crew intended to tell federal safety investigators Sunday.
During a session with a team from National Transportation Safety Board, these people said, the cockpit crew intended to recount the same sequence of events it previously sketched out for airline superiors: They became distracted in conversation while cruising at 37,000 feet Wednesday night, didn't realize how long the plane had lost radio contract and flew well past their airport destination. Such a scenario is consistent with the brief statements first officer Richard Cole of Salem, Ore., made to reporters earlier in the weekend.
During the 78-minute radio silence, controllers became so concerned about the fate of the 149 people aboard that they asked pilots of other aircraft in the vicinity to see if they could rouse the Northwest crew, according to industry and government officials. When that failed, the Federal Aviation Administration began to consider having military jets scrambled to intercept the twin-jet Airbus A320, these officials said.
The incident--which pilots and safety experts consider a bizarre break from routine procedure--had the plane crossing various air-traffic control zones and being passed to different groups of controllers without any verbal response. It comes as federal regulators, lawmakers and airlines are focusing on the issue of pilot fatigue and debating possible changes to rules that spell out how long pilots can fly or be on duty in a 24-hour period.
Safety officials at Northwest and its parent, Delta Air Lines Inc., appear to support the pilots' statements, according to one person involved in the deliberations. Even so, government investigators are pressing to see whether fatigue may have played a role in the bizarre flight of the Airbus A320 with 149 people aboard.
With the probe picking up steam, some pilots and safety experts who initially strongly suspected snoozing pilots are tempering their position in light of additional data. One new factor, for example, is that Delta has confirmed that the crew's schedule that day wasn't especially demanding. And fatigue experts have weighed in to note that the evening hours when the incident occurred typically don't pose particular challenges for the internal body clocks of pilots.
But without clear-cut data from the plane's cockpit-voice or flight-data recorders, it may be hard for investigators to conclusively back up pilot assertions or precisely determine what happened. Spokesmen for Delta and the safety board declined to comment.