WASHINGTON – Investigators will be taking a meticulous look at why a regional jet apparently took off on the wrong runway and whether passengers could have been evacuated before it erupted in flames, killing 49 people.

Authorities determined early on from flight data yesterday that the pilots rolled out on Runway 26, which is too short for the regional jet they were flying – a CRJ100 – to take off.

“Our investigations are very thorough,” National Transportation Safety Board member Debbie Hersman said at a news conference in Lexington, Ky. “We have ground scars at the end of Runway 26 as well as some preliminary information from the flight data recorder that shows the aircraft was lined up on a heading of 26 on takeoff.”

She said investigators also have found that although the fuselage apparently was intact in a grassy area beyond the runway at Lexington’s Blue Grass airport, portions of the wing and the tail were in another area.

The airplane was engulfed in a devastating fire, and the only survivor, the first officer, was taken from the scene in critical condition.

The other passengers and crew appeared to still be on the plane and their deaths were caused either by the impact or the fire on board, said Fayette County Coroner Gary Ginn.

Peter Goelz, former managing director of the NTSB, said a survival factors group will try to determine how the passengers perished: by blunt force trauma, smoke inhalation or burn.

“They’ll try and figure out from the position of the victims whether an evacuation was possible,” Goelz said. “From the location of the bodies, they may be able to tell whether an evacuation was attempted.”

The emergency response also will be examined, Goelz said. “How quickly did they get there? Did they have the appropriate firefighting materials? Did they put the right stuff on in a timely manner.”

Investigators will try to reconstruct what led the pilots to attempt to take off on a short, narrow, runway made of old concrete that was supposed to be unlit, rather than a long, wide runway that was recently resurfaced and had border markers, said Paul Czysz, professor emeritus of aerospace engineering at Saint Louis University.

The airplane needs to roll at least 5,000 feet before it gains enough speed to become airborne, said John Goglia, former NTSB board member.

The shorter runway is 3,500 feet, according to the FAA, the longer runway 7,003 feet.

Pilots should have noticed the difference between the two runways, the blue taxi lights and the lit runway markers, he said.

Controllers in the tower should have also noticed what runway the pilots were on when they asked permission to take off, Czysz said.

Goglia said there could be an explanation for how the crash happened.

“They’re taxiing out from the terminal, no one’s in front of them, so they’re going quickly,” Goglia said. “One pilot’s got his head down,” he said, entering data into the flight data computer.

Goglia said he understood the shorter runway was lit in some way, though the FAA’s formal notice to pilots said there were supposed to be no lights on the runway.

“He’s looking for runway lights, he sees them, he’s given clearance,” Goglia said. “There’s one guy in the tower and he’s moved on to other duties.”

Terry McVenes, executive air safety chairman for the Air Line Pilots Association, International, said the effects of recent construction on the runway will be an important factor in the investigation. Construction lights, for example, may have confused the pilots.

The airport’s main runway had also been resurfaced just a week before the crash.

“The role of the construction and the lighting – that’s one of the factors that’s going to be important,” McVenes said.