Jan 6, 2009 9:01 pm US/Mountain
Safety Experts Cite Crosswinds In Denver Air Crash
By Joan Lowy, AP Writer
WASHINGTON (AP) ―
Aviation safety experts said Tuesday strong crosswinds likely were a factor in an accident last month that sent a Continental Airlines jet into a bone-jarring veer off a Denver runway and across open, snowy fields before it came to a halt and caught fire.
Several safety experts raised the possibility that the Boeing 737-500 airliner, carrying 110 passengers, may have experienced "weather vaning," where a strong crosswind pushes a plane's tail and turns the aircraft's nose into the wind, much like it turns a weather vane.
While gusts of up to 37 mph were reported at Denver International Airport on the day of the accident, the experts said, winds were probably not strong enough to explain the accident entirely, and some additional factor -- either mechanical failure or human error -- also could have played a role.
"My suspicion is that the crosswind was definitely a factor," said Eric Doten, an aviation safety consultant and adjutant faculty member at Embry-Riddle Aeronautical University in Daytona Beach, Fla.
"If there's nothing wrong with the engines and nothing wrong with the gear and nothing wrong with that airplane that they can find, then I would suspect that wind is going to end up being the culprit, and that what happened to the airplane is the result of some reaction to the wind, either by the airplane or by the pilot," Doten said in an interview.
Continental Airlines flight 1404 was taking off for Houston on Dec. 20 when the accident happened, injuring 37 people. The main landing gear was sheared off, its nose gear collapsed, and the plane came down on its belly about 2,000 feet from the runway.
National Transportation Safety Board 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."
One of the puzzles confronting federal investigators is why the jet suddenly turned left off the runway and headed roughly west into gusting crosswinds. Sensors on the runway at the time of the takeoff measured the wind at 31 mph, according to the NTSB, and weather reporting stations on the airport field measured gusts of up to 37 mph.
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.
Safety experts said the flight's pilots should have been able to compensate for crosswinds.
Doten cautioned that it's still possible there was a mechanical failure involving the nose wheel or some other part, "so you can't say it's definitely a failure on part of the crew to react properly."
NTSB has not identified the plane's pilot, and the Air Line Pilots Association declined to comment.
Former NTSB chairman James Burnett said there's no guarantee that the crosswind safety guidelines are correct for all circumstances.
"It could be that the parameters for crosswinds should be tighter," Burnett said. He noted that the issue seems to be how quickly the pilots reacted "when they first detected some sign of something being amiss," and whether the takeoff should have been aborted as a precaution.
"I don't want to suggest I know the answer to that question, but that's something that's going to be examined," Burnett said.
But John Nance, a former pilot and aviation safety consultant, was skeptical 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 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."
(© 2009 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)
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