the Associated Press

LEXINGTON, Ky.— A commuter jet crashed during takeoff early Sunday and burst into flames, killing 49 people and leaving the lone survivor – a co-pilot – in critical condition. Investigators were trying to determine if the plane was on the wrong runway and ran out of pavement. Atlanta-bound Comair Flight 5191 crashed at 6:07 a.m. in a field less than a mile from the shorter of Blue Grass Airport’s two runways.

The main runway is 7,000 feet long, but the shorter one is just 3,500 feet and unlit, designed mostly for small private planes. Aviation experts said the twin-engine CRJ-200 regional jet would have needed 4,500 feet to fully get off the ground.

Neither the Federal Aviation Administration nor Comair, a subsidiary of Delta Air Lines Inc., would speculate on the cause of the crash or say which runway the plane was on. But aerial images of the crash showed trees damaged at the end of the shorter runway and the nose of the crashed plane almost parallel to the smaller strip.

The plane was largely intact but in flames when rescuers reached it. A police officer burned his arms dragging the only survivor from the cracked cockpit, but the fire kept rescuers from reaching anyone else.

The crash was the country’s worst domestic airplane accident in nearly five years.

FAA spokeswoman Laura Brown said the agency had no indication that terrorism was involved in any way. Both flight recorders, which should help investigators determine what went wrong, were sent to Washington, D.C., for analysis.

The location of the wreckage makes it almost inconceivable that the airplane could have taken off on the longer runway, said Saint Louis University aerospace professor emeritus Paul Czysz.

“Sometimes with the intersecting runways, pilots go down the wrong one,” Czysz said. “It doesn’t happen very often.”

The three-member flight crew aboard the Comair plane that crashed in Lexington was experienced and had been flying that airplane for some time, said Comair President Don Bornhorst.

“We are absolutely, totally committed to doing everything humanly possible to determine the cause of this accident,” Bornhorst said. “One of the most damaging things that can happen to an investigation of this magnitude is for speculation or for us to guess at what may be happening.”

The only survivor of the crash was identified as first officer James M. Polehinke, hired in 2002, who was in critical condition after surgery at the University of Kentucky hospital.

The other crew members were Capt. Jeffrey Clay, who was hired by Erlanger, Ky.-based Comair in 1999, and flight attendant Kelly Heyer, hired in 2004.

The plane had undergone routine maintenance as recently as Saturday and had 14,500 flight hours, “consistent with aircraft of that age,” Bornhorst said.

The FAA and the National Transportation Safety Board were investigating, and Bornhorst said the airline was trying to reach passengers’ relatives.

The crash marks the end of what has been called the “safest period in aviation history” in the United States. There has not been a major crash since Nov. 12, 2001, when American Airlines Flight 587 plunged into a residential neighborhood in Queens, N.Y., killing 265 people, including five on the ground.