Moral of this story: If your plane is flying out of control, don't try and recover, you'll upset things: <img src="rolleyes.gif" border="0">
From the New York Times
[quote]Investigators looking into the crash of an American Airlines flight in Queens in November have so far found no pre-existing flaw in the jet's tail section and are now focusing on the performance of the pilots, who they believe triggered the airplane's wild rolling and yawing in the seconds before it went down.
The data recovered from American Airlines Flight 587 showed that the plane hit turbulence from a plane in front of it and seconds later, began to swing violently and break up before it fell 2,900 feet to the ground, killing 265 people. The vertical tail of the plane, and the rudder attached to it, were the first parts to break off, and investigators began to look early on at whether that caused the crash, possibly because of some undetected flaw.
But now, after extensive testing of the tail, they have found no pre-existing problem. And so they are intensely exploring whether the pilots, in trying to correct and control the plane after the turbulence, might have put more stress on the tail than it was designed to handle.
"A brand-new tail would have broken," said one investigator, underlining his belief that the effort by the pilots to control the plane set in motion the fatal series of events. Another investigator involved in the National Transportation Safety Board's inquiry pointed out that it is possible to take an airplane in perfect condition and maneuver it into a breakup, just as a driver could take a sport-utility vehicle in perfect condition and make a radical maneuver at high speed that results in a rollover or other accident.
The plane that crashed, an Airbus A300, is a long airplane — 177.5 feet — and with the fuselage acting like a long lever, sudden movements from side to side produce powerful pressures at the end, where the vertical tail sits. By international regulation, the tail is supposed to be able to withstand a force 50 percent stronger than the largest it is likely to ever encounter, and Airbus officials said that the A300 tail exceeded even that standard. But investigators now believe that the tail was overstressed.
The latest developments in the investigation come eight weeks after the American Airlines plane bound for the Dominican Republic went down in Belle Harbor, on the Rockaway Peninsula in Queens, shortly after takeoff from Kennedy International Airport on Nov. 12.
And although investigators are interested in the latest theory, they emphasize that they are far from declaring a definitive cause. Indeed, some are still trying to determine if the rudder moved differently from the way the pilots intended. The investigation is being led by the N.T.S.B., with the participation of the F.A.A., Airbus, American Airlines, the union that represents American Airlines' pilots and other aviation experts.
Investigators had focused originally on the rudder and the vertical portion of the tail to which it attaches, both of which fell off the plane. The tail is made of carbon-reinforced plastic, a composite material that has come into common use in airplane structures only in the last 15 years and investigators have relatively little experience with it.
The Safety Board had the tail trucked to a NASA laboratory in Hampton, Va., for analysis. But the lab has turned up no sign of fabrication error or damage to the tail before the accident, according to people involved in the investigation. Now, investigators think it tore off because of the increased strain placed on it by the pilots' maneuverings — rolling and skidding the plane in the air.
The Airbus had hit the wake of a Boeing 747 that was about five miles ahead of it, which is considered a safe distance. That preceding plane created what investigators say was a minor bump, but the encounter may have prompted the Airbus crew to try to compensate.
"They thought they had something from which they thought they needed to recover quickly," said one investigator, reflecting the current hypothesis. At the controls of the jet was the first officer, Sten Molin, 34. Mr. Molin was an experienced pilot, with 4,400 hours of flying time, 1,835 of them as co-pilot of an A300.
After using the flight controls to steady the airplane, the objective normally would have been to bring it back to its previous orientation — in this case climbing and banking slightly to the left in its first turn out of Kennedy.
"Before they could do that, something else happened," the investigator said.
Several investigators said the training of pilots would be carefully examined. Crews at American were trained in the mid-1990's to use the rudder to recover from "flight upsets," but Airbus, Boeing and the F.A.A. later warned against this practice, saying it could produce dangerous stresses. American said it changed its training in 1999 to de- emphasize use of the rudder. Evidence recovered from the plane's data recorder indicates that the pilots were using the rudder to try and stabilize the plane.
The investigators are finding their work slowed by limitations on their tools. One tool is a computer-driven simulator owned by Airbus, which can predict what happens to the plane with each change in rudder or other control surfaces.
But the computer does not make good predictions at dangerous angles, because it is difficult to conduct test flights to gather such data. "You don't do extremely weird things to airplanes" to gather such data, one investigator said. As a result, he said, "When you get in a situation way outside the envelope of the airplane, you don't know."<hr></blockquote>
I would expect more from the New York Times, to be quite honest. It is somewhat infuriating the way they can twist one of the various theories (without displaying objectivity and comparing it to others) to make a lay-public believe this nonsense.
Any comments?
SFly <img src="eek.gif" border="0">
[ 05 January 2002: Message edited by: SFly ]</p>