Saturday, May 17, 2008
Those who fly planes want to know why the autopilot was disconnected, the engines were shut down and nobody contacted air-traffic controllers.
Nov 16, 1999 | The mystery deepens. The latest data from the EgyptAir Flight 990 voice recorder show that someone sitting in the co-pilot's seat uttered a prayer as something went terribly wrong with the flight. As alarms sounded in the background, someone struggled to save the plane, but inexplicably failed.
Pilots and investigators held high hopes for that voice recorder, expecting it to explain the many problems of this crash. Early flight data hinted at some sort of pilot-induced cause, a possible intentional crash. While news yesterday focused on the seemingly normal banter between the pilots as something went wrong with the flight, today's news about the utterance of a prayer before the autopilot disengaged remuddles the waters.
Were the pilots acting together, brilliant saboteurs who played the game all the way to the ground? It's doubtful, when they simply could have disabled the voice recorder, as an apparently suicidal pilot on Indonesian carrier Silkair did before pointing the nose of his 737 straight down in 1997, killing all aboard.
As a pilot myself, I was convinced that the voice recorder would reveal a frantic cockpit battle as one pilot struggled to save his craft while the other fought to nose in. I believed it not because of erroneous newspaper reports about how the recovered control surfaces pointed in opposite directions, which led "experts" to conclude that the pilots must have been wrestling over the yoke.
The reason I believed the battling-pilot theory was because of the disconnection of the autopilot -- the first of many mysteries about this crash. The plane was cruising, set up for a long overseas flight, the autopilot calmly tracking the radio beacons and holding altitude. It's common airline procedure to hand the flight over to autopilot shortly after taking off, and very unusual that someone would turn it off until landing. One reason would be if the plane decompressed, as Payne Stewart's Learjet apparently did. Procedure is for pilots, who have seconds to live at that altitude, to put on oxygen masks, disconnect the autopilot and quickly descend to 10,000 feet.
The early readings of the voice recorder bear the sabotage theory out. If both pilots were in cahoots, or one of them disabled, that would explain both the autopilot disconnect and lack of radio contact, the second of the mysteries surrounding the investigation. If they were working together to solve some sort of mechanical problem, the pilots certainly would have called air controllers.
A commercial pilot on an overseas flight plan can talk to a radar controller at any time by simply pushing a small button on the airplane's control yoke, then speaking into his headset's microphone. It's a one-finger operation, easily performed while flying.
Surely one of the two or three people in that cockpit had a second to push the button and say, "Uh, New York, we've got a little problem here." The plane dived for 40 seconds, each of them surely seeming like minutes.
Admittedly, pilots are trained to fly first, talk second. Yakking to air traffic control isn't going to save a falling plane, which would demand a pilot's full attention. But in 40 seconds of diving and a few of climbing, didn't at least one crew member have a moment to radio in an emergency call? Yes, unless they were somehow prevented from calling.
The third mystery is how and why the engines were shut down. Airplane engines aren't turned off by keys but by cutting off the fuel supply -- which may have happened just before this airplane climbed. Recovering from a steep dive puts tremendous pressure on the airframe, which can actually yank off the wings and tail.
Pilots familiar with the plane say there is no operating handbook procedure for a Boeing 767 recovery from a descent as steep as this one made.
But the first step in any dive recovery is to reduce air speed, which means reducing power. Is it possible that one of the pilots, in a frantic attempt to slow the machine down before pulling the nose up, instead cut the engines completely? The two procedures are difficult to confuse, so it's almost certain that the pilot to turn the power plants off. And then climb? It is possible, unlikely, pilots say, that a Boeing 767 could gain 8,000 feet without power.
Pilots, like everyone else, are bewildered by this crash. Like the non-flying public, we want answers. But pilots want answers that we can learn from. The early clues from Flight 990 pointed toward a hijacker, bomb, insane copilot -- these causes are not as interesting to pilots, because the chances of them happening again are rare, and the chances of a pilot being able to save his or her plane from them even rarer.
Explanations grounded in "pilot error" -- the No. 1 factor in small plane and commuter crashes, No. 2 in commercial (bumping into each other while taxiing is No. 1) -- are instructive. We study them to learn how to avoid re-creating the ill-fated pilot's mistake, living to fly again another day.
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