"The cockpit voice recorder went on for two hours, but the last 18 minutes were most pertinent, because those words proved that it was a tire blowout that [may have] caused the crash killing four people," Debbie Hersman, board member of the National Transportation Safety Board in Washington, D.C., tells PEOPLE.
"After getting their clearance from Air Traffic Control, the plane only got 80 knots on the 8,600-foot runway before the incident," she said.
Pilot Sarah Lemmon, 3l, co-pilot James Bland, 52, security guard Charles Still, 25, and Barker's assistant Chris Baker, 29, were killed instantly.
Barker, 32, and DJ AM (real name: Adam Goldstein), 35, are in critical but stable condition in the intensive care unit of a burn center in nearby Augusta, Ga.
Attempt to Abort TakeoffThe crew tried to abort takeoff, the recording stated, and there were many background and impact sounds on the tape. The voice tapes from the control tower were equally revealing.
"The Air Traffic Control tapes stated that they gave the crew clearance to depart, as well as the wind speeds," said Hersman, who is in Columbia with 11 other investigators from the NTSB.
"The tapes went on to say they saw sparks and heard the crew on the plane explaining that they were going off of the runway," she said.
At 100 feet past the end of the runway, the 2-year-old plane came to its final rest.
"We are doing a lot more investigating because, while it is not uncommon to blow a tire, it is rare for something like that to end in a fatal accident," says Hersman.
"Reasons could be anything from inflation levels, materials, punctures, design, etc. So we are doing everything in our power to learn what transpired and make recommendations so nothing like this ever happens again."