From cnn.com:
Washington (CNN) -- The Southwest Airlines jet that crash landed at New York's LaGuardia airport on Monday met the runway with its nose gear first, according to federal accident investigators.
The unusual landing, in which investigators said the plane's nose pitched down seconds before touchdown, is the surest clue yet as to why the Boeing 737s front landing gear collapsed and the plane skidded down the runway.
The National Transportation Safety Board said on Thursday that video and other sources provide evidence that the nose gear contacted the tarmac before the main wheels.
Under a normal landing in a big jet, the main landing gear under each wing would touch the runway first and simultaneously -- absorbing the main stress of landing -- and the nose gear then lowered gradually as the plane decelerates down the runway.
The safety board did not speculate as to why the plane landed the way it did. That model jet is expected to cross the runway threshold at about 140 knots or 161 mph, according to Boeing figures.
Investigators said the pilot evidently adjusted the wing flaps less than a minute before landing, suggesting to veteran pilots who spoke with CNN that the plane may not have been on a stabilized approach as it neared the runway.
Landing the way it did "would potentially have overstressed the nose gear to the point where it would have failed," said Capt. Mark Weiss, a former 737 pilot and civil aviation leader at The Spectrum Group in Washington.
The NTSB said the plane's wing flaps were set from 30 to 40 degrees about 56 seconds prior to touchdown.
"What this brings into question is whether they were on a stabilized approach to make a normal landing," Weiss said.
The safety board, coincidentally, is looking at whether Asiana Flight 124, which crashed-landed in San Francisco earlier this month, was also on a stabilized approach.
Details released late Thursday about the New York accident show the plane changing its pitch suddenly in the final seconds of flight -- and in a direction opposite than desired.
When the plane was just 32 feet in altitude, four seconds before landing, the plane was pitched 2 degrees nose up. At touchdown, the plane was pitched approximately 3 degrees nose down, the safety board said.
Video shows the plane careening down the runway, the nose to the pavement, sending up showers of sparks. After touchdown, the aircraft came to a stop within approximately 19 seconds, the NTSB reported.
Word that the landing was unusual could remove suspicion of a mechanical failure. Such a conclusion could have major implications for commercial aviation worldwide, given the 737's status as the most widely used commercial jet.