Southwest Airlines Flight 345 touched down first on its front landing gear, sending the jet with 150 people aboard skidding to a stop at LaGuardia Airport on its nose, federal investigators said Thursday.
The Boeing 737-700 was pitched 2 degrees nose up when it was 32 feet above the runway and 4 seconds from landing, but at touchdown, the aircraft pointed down about 3 degrees, the National Transportation Safety Board said.
The latest findings about the Monday landing are based on an initial exam of flight data and cockpit voice recorders, the NTSB said.
Video and other sources show the nose gear hitting Runway 4 at 5:40 p.m., then collapsing immediately, the agency said.
Planes typically touch down on the main landing gear beneath the wings, with the nose pointed upward.
Southwest spokesman Brad Hawkins said a nose-first landing, if done intentionally, would violate its procedures.
"The landing scenario the NTSB describes from video and other sources is not in accordance with our operating procedures," he said.
John Goglia, an air safety consultant and former NTSB member, said the data indicate something happening so late in the landing sequence that the crew was "overtaken by the event."
"Something unexplained happened at the last second," he said. "Being that close to the ground, there was nothing the crew could do. They were along for the ride."
Transcribers plan to meet Friday to work on the cockpit voice recorder, which contains a two-hour recording of "excellent" quality that captures the entire Nashville-to-New-York flight, NTSB said.
The flight data recorder contains about 27 hours of data, it said.
The months-long investigation will focus first on collecting all the "perishable" evidence, such as plane debris, before moving on to other data, including weather reports, that can explain factors in the accident, said NTSB spokesman Eric M. Weiss.
"Our investigation is broken down into three broad categories: people, the machines and the environment," he said.
Ten passengers were injured and six were taken to hospitals, authorities said, while four crew members went to a separate hospital for observation.
The jet slid 2,175 feet and stopped after about 19 seconds, the NTSB said.
The front landing gear penetrated the fuselage, damaging the bay that houses the plane's electronics, the agency said the day after the crash.
Only the right axle was attached to the landing gear, investigators said, and a photo taken by the agency shows damaged gear jammed up against rows of electronics.
With Zachary R. Dowdy