Lexington, KY ? There was one air traffic controller on duty the morning Comair Flight 5181 crashed, and federal investigators said Tuesday that he cleared the jet for takeoff, then turned his back to do “administrative duties” as the aircraft went down the wrong runway.

The crash Sunday killed 49 people – everyone on board except first officer James Polehinke. The air traffic controller had an unobstructed view of the runways and had cleared the aircraft for takeoff from the longer runway, said National Transportation Safety Board member Debbie Hersman.

The commuter jet struggled to get airborne after taking off from a 3,500-foot runway instead of an adjoining one that was twice as long. Experts said the plane needed at least 5,000 feet for takeoff.

Also Tuesday, Hersman said the crew checked in at 5:15 a.m. but boarded the wrong plane at first. They started preparations before a ramp worker alerted them to the error.

The Federal Aviation Administration on Tuesday acknowledged violating its own policies when it assigned only one controller to the airport tower that morning. The policy is outlined in a 2005 directive requiring that control tower observations and radar approach operations be handled separately.

FAA spokeswoman Laura Brown said the controller had to do his own job – keep track of airplanes on the ground and in the air – as well as radar duties.

The controller had been working at the Lexington airport for 17 years and was fully qualified, Hersman said.

The only survivor, Polehinke, was piloting the plane at the time, Hersman said, but it was the flight’s captain, Jeffrey Clay, who taxied the aircraft onto the wrong runway, Hersman said. Clay then turned over the controls to Polehinke for takeoff, the investigator said.

Dr. Andrew Bernard, a surgeon at the University of Kentucky Hospital, said it was a miracle that Polehinke was still alive. He suffered facial fractures; two spinal fractures; a complex pelvis fracture; a broken leg, foot and hand; three broken ribs; a broken breastbone; and a punctured lung.

Polehinke had a clean record as a pilot, with no accidents or mistakes, authorities said.