LEXINGTON, KY. ? Pilots of a Comair jet that crashed on takeoff noticed there were no lights as they prepared to take off, but they didn’t recognize they were headed down the wrong runway, investigators said Monday.

The only survivor in the crash that killed 49 people, first officer James M. Polehinke, was piloting the plane, said Debbie Hersman, a National Transportation Safety Board member. He remained in critical condition Monday at the University of Kentucky Hospital.

The cockpit voice recorder showed that the pilots were talking about the absence of lights on the runway but that they didn’t report it to the lone air traffic controller in the control tower, Hersman said.

Investigators were looking into whether the runway lights or changes made to a taxiway during a repaving project a week ago confused the commuter jet’s pilot and caused him to turn onto the wrong runway.

Both the old and new taxiway routes cross over the short runway where Flight 5191 tried to take off before crashing into a grassy field and bursting into flame, Airport Executive Director Michael Gobb told The Associated Press.

“It’s slightly different than it used to be,” said Charlie Monette, president of Aero-Tech flight school at the airport. “Could there have been some confusion associated with that? That’s certainly a possibility.”

It was unclear whether the Comair pilots had been to the airport since the changes to the taxi route.

Lowell Wiley, a flight instructor who flies almost every day out of Lexington, said in an interview that he was confused by the redirected taxi route when he was with a student Friday taking off from the main runway. “When we taxied out, we did not expect to see a barrier strung across the old taxiway,” Wiley said. “It was a total surprise.”

Investigators planned to use a high truck to simulate the pilots’ view of the runways and taxiways in their efforts to determine why the jet turned onto a shorter runway before dawn Sunday.

Authorities also planned to prepare a full report on the pilots, including what they did on and off duty for several days before the crash, the worst U.S. plane disaster since 2001.

All discussions between the plane and the control tower were about a takeoff from the main strip, Runway 22, which is 7,000 feet long, Hersman said.

Two other flights departed without problems, but somehow the commuter jet ended up on Runway 26 instead – a cracked surface about 3,500 feet long that forms an X with the main runway and is meant only for small planes. Aviation experts say the CRJ-100 would have needed 5,000 feet to get airborne.

Although both runways at Blue Grass Airport have lights along the edges, although the shorter runway is for daylight operation only, and its lights haven’t worked since October 2001. The long runway also has lights in the center. In the days leading up to the crash, those runway center lights were not working, according to a notice the Federal Aviation Administration sent to airlines.

An employee for another airline saw the accident and told investigators the main runway lights were lit, Hersman said.