The bumping and rattling sound was first heard 41 seconds after the plane started down the runway, said Robert Sumwalt, a spokesman for the National Transportation Safety Board. Four seconds later, one of the crew members called for the takeoff to be aborted. The recording ends six seconds later, probably because the plane slammed down on the ground after hurtling off an embankment, Sumwalt said.
Thirty-eight people were injured, including the plane's captain. Sumwalt said investigators have found no problems with the plane's engines, tires or brakes, but are not yet ruling anything out. He said investigators will be looking for other evidence that could be linked to the bumping and rattling sound.
The plane traveled about 2,000 feet after leaving the runway, crossing a grassy strip and a taxiway before going off the embankment, hitting the ground at its base. It then went up a slight hill, over an access road and then down another small hill on the other side of the road before landing on its belly, its landing gear shorn off.
Lead NTSB investigator Bill English said the plane's data recorder shows the thrusters on both of the plane's engines were switched to reverse. He said that normally happens when crew members try to stop a takeoff.
Sumwalt said investigators are still gathering information about the exact wind conditions on the runway at the time of the accident. However, he said the cockpit recording contained no comments about wind.
Investigators have not yet interviewed the plane's captain, who was flying the plane, because Sumwalt said he is physically unable. He didn't elaborate. They have talked to the first officer, who said the plane began moving off the center of the runway as it reached about 103 mph while speeding down the runway for takeoff.
The plane continued to accelerate, reaching a maximum speed of about 137 mph, Sumwalt said.
Off-duty crew members who had flown the plane earlier in the day also were on board at the time of the accident, and Sumwalt said the first officer from that crew returned to the plane three times to help rescue passengers. Sumwalt also reported that those crew members said they had no problems with the plane during their flight.
A fire charred and ripped open much of the right side of the plane, with the worst damage around a crack around the fuselage. Sumwalt said all the passenger seats remained intact during the plane's wild ride off the runway, although seats in row 18, near the crack, had loose fittings.
Sumwalt said the runway was bare and dry at the time of the crash and no debris was found there.