(February 2012) Increasingly, flight is automatic. Navigation no longer requires an ounce of brains. Auto-pilots climb and descend, hold altitude, track waypoints and execute entire flight plans while idled crews ponder football scores. Autoland systems bring airplanes safely to earth, and even to the decks of aircraft carriers, in zero-zero weather. Only one phase of flight remains uninvaded by automation: the takeoff.
Too difficult? You wouldn’t think so. Certainly the basic act of taking off — throttles forward, hold centerline, rotate — could easily be automated. If there’s any complication, it’s in the element of judgment that arises — very seldom — when an engine fails, a tire blows, a deer strolls onto a darkened runway or some odd and inexplicable thing happens to befuddle and paralyze the pilot. It’s not that a computer could not deal with these eventualities as well as a human can — not always very well, to tell the truth — but rather that the possible vicissitudes of takeoff are so various, and the proper reactions to them so dependent on circumstances, that no program could foresee them all.
Here are two takeoffs that went bad. The conditions and the equipment involved were completely different; the outcomes were the same.
The density altitude was over 6,400 feet when a Beech A36 with three aboard, including an instrument student and his instructor, began its takeoff roll. There was an 11-knot quartering headwind, gusting to 24. The runway length, 5,100 feet, should have been ample: Handbook performance, which the flight school required that pilots record in writing prior to each takeoff, predicted a ground roll of 1,900 feet.
The engine sound drew the attention of several witnesses. One, his memory perhaps retrospectively influenced by what was soon to happen, described the engine as “clanking and banging ... like a thresher machine,” but several others said it was steady and smooth. One of those, a CFI and mechanic with 30 years’ experience in general aviation, first saw the airplane when it was a third of the way down the runway. He immediately felt that something was wrong. The engine sounded “like it was turning about 2,300 rpm.” He kept saying to himself, “Shut down. Shut down.” But the airplane continued, not accelerating appreciably, and rotated when three-quarters or more of the runway was behind it. The nose came up, but the airplane rolled another 200 yards on its mains before breaking ground.
It climbed only a few feet, snagged a seven-foot-high boundary fence with its left main gear, crossed a canyon and struck a wooded slope a thousand feet from the airport boundary, killing all three occupants.
Examination of the engine and what was left of the airframe — the cabin area was consumed by fire — yielded no evidence of a mechanical malfunction. The only noteworthy fact was that the light gray color of the spark plugs suggested lean operation, which became “excessively lean” in the summary version of the accident report.
