January 7, 2009
By JOAN LOWY
WASHINGTON (AP) — It was very windy when a Continental Airlines jet was destroyed while trying to take off in Denver last month, leading aviation safety experts to cite crosswinds as a likely factor in the accident.
But were those winds strong enough to “weather-vane” the Boeing 737-500? In that phenomenon, the wind pushes an airliner’s tail hard enough to swing its nose into the wind, like a weather vane. In Denver, experts suspect weather-vaning caused the plane to skitter off the runway in a bone-jarring ride across open, snowy fields, eventually coming to a halt and catching fire. But some additional factor — either mechanical failure or human error — probably also played a role, safety experts said.
Crosswinds were “definitely a contributing factor,” said John Cox, a former pilot and president of Safety Operating Systems, an aviation consulting firm in Washington. “Whether it’s causal or not, I don’t think you have enough information to go there yet,”
Gusts of up to 37 mph were reported at Denver International Airport on the day of the accident, according to the National Transportation Safety Board. Cox and other experts said those gusts may have been strong enough to push the aircraft’s tail around, but the plane’s pilots should have been able to compensate.
Continental Airlines flight 1404 was taking off for Houston on Dec. 20 when the accident occurred. The main landing gear was sheared off, its nose gear collapsed, and the plane carrying 110 passengers rumbled about 2,000 feet from the runway. Thirty-seven people were injured.
NTSB officials have said the plane’s brakes and engines appeared to have been operating normally. Investigators dug the destroyed nose gear out of the ground last week, and safety board spokesman Peter Knudson said preliminary results of that examination may be available later this week.
“We’re looking at (crosswinds), but it’s just one thing we’re looking at,” Knudson said. “Nothing is off the table.”
Spokesmen for Boeing and Continental declined to reveal their guidelines on safely operating the 737-500 in crosswinds. However, Knudson said the winds at the time of the accident should have been “within the envelope” of what the plane could withstand.
NTSB has not identified the plane’s pilot, and the Air Line Pilots Association declined to comment.
But John Nance, a former pilot and aviation safety consultant, was doubtful that crosswinds will ultimately be shown to be a cause. He said wind created by the plane’s velocity as it gained speed heading north down the runway would have offset the impact of the crosswinds from the west.
“It would have taken a mighty burst of wind way, way above anything anybody has recorded, in my view,” Nance said.
Also, he said, compensating for the type of crosswinds experienced in Denver that day would have been second nature for an experienced pilot, “just like riding a bicycle.”
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