Aug. 28 (Bloomberg) -- A Delta Air Lines Inc. Comair commuter jet didn't use the runway assigned by air traffic controllers just before taking off from a Kentucky airport and crashing, killing 49 people.

Conversations between the pilots and the Blue Grass Airport control tower gave no indication the plane would fly from another, shorter runway, Debbie Hersman, a National Transportation Safety Board investigator, said today.

Flight 5191 departed in predawn darkness yesterday from the unlighted 3,500-foot Runway 26 at the Lexington, Kentucky, airport. The strip is half the length of Runway 22, which is normally used by commercial jets such as the Comair 50-seat CRJ- 100.

``Air traffic controllers and the flight crew planned for takeoff from Runway 22,'' Hersman said. ``Evidence on the scene indicates the crew took off from Runway 26.''

There were no references to the shorter runway on tapes from the control tower or the cockpit, she said. The cockpit voice recorder, which was recovered along with the flight data recorder, contains 32 minutes of conversation, Hersman said.

A fully loaded CRJ-200, a 50-seat replacement for the CRJ- 100, requires at least a 5,800-foot runway for takeoff, according to the Web site of manufacturer Bombardier Inc. The Comair plane crashed into a horse farm off the end of Runway 26.

One Controller

Hersman declined to say how the pilots of Atlanta-bound Flight 5191 might have ended up on Runway 26. One air traffic controller was on duty, which was normal for the airport at the time of the 6:19 a.m. crash. The first officer was critically injured and was the only survivor among 47 passengers and three crew members.

Pilots flying into the airport had been notified as recently as Aug. 25 about construction on the runways that could result in changes such as lighting, Hersman said.

``It's my understanding all the lights on Runway 26 were out of service,'' Hersman said. ``I don't know about the lights on Runway 22. There were aircraft that took off before'' Flight 5191.

In a 1993 incident, another airliner taxied into takeoff position on Runway 26 amid poor visibility after being told to use Runway 22, the pilot of that plane said in a report. The crew and controllers realized the error moments later, and the plane was redirected to a safe takeoff from Runway 22.

The report was made in the Aviation Safety Reporting System, a database set up by the Federal Aviation Administration and National Aeronautics and Space Administration. It didn't identify the pilot or the airline involved.

Takeoff Procedures

Pilots typically confirm their takeoff runway with flight controllers more than once in pre-flight checklists, and the Comair jet's computer software would have displayed the correct runway, said Bruce ``Buck'' Rodger, chief technical officer for the consulting firm Aviation Experts in San Clemente, California, and a United Airlines pilot.

``One of the most difficult parts of flying for a pilot is taxiing to the runway'' because of confusing signage and the presence of other aircraft, Rodger said in an interview.

Tricky Runways

The Lexington airport's configuration could be tricky for pilots, he said. Runways 22 and 26 are close together, and both require a left turn to enter from the taxiway, Rodger said.

There was no discussion of equipment problems before takeoff, and early evidence shows the regional jet's General Electric Co. engines were in ``good working order,'' Hersman said.

Investigators also found no indications of terrorism, said David Beyer, a special agent for the Federal Bureau of Investigation in Lexington. The FBI, NTSB and Federal Aviation Administration are all part of the crash inquiry, which may run a year or longer before the safety board rules on the cause.

The survivor was First Officer James Polehinke, 44, who was pulled from the cockpit by rescuers after the jet struck trees near the runway and caught fire. He remained in critical condition today at the University of Kentucky Chandler Medical Center in Lexington, said Matt Cantor, a hospital spokesman.

Comair, which is based in Cincinnati, identified the other crew members as Captain Jeffrey Clay, 35, and flight attendant Kelly Heyer, 27. Clay joined Comair in November 1999, Polehinke in March 2002 and Heyer in July 2004.

Crew Rest

The Comair crew began the flight after a rest period ``well beyond what is required by the FAA and what is standard for our own airline,'' President Don Bornhorst said. The crew spent the night in Lexington, Comair said, declining to be more specific.

The crew's rest time and their activities for at least 72 hours before the crash are part of the NTSB investigation, Hersman said. The FAA requires pilots have a minimum eight hours of rest in any 24-hour period that includes flight time. Scheduling and rest periods also are set in contracts negotiated between pilot unions and airlines.

``Fatigue is a huge factor in almost every crash,'' said Jon Kettles, a Dallas-based attorney who specializes in air crashes.

Comair followed Atlanta-based Delta in filing for bankruptcy reorganization last year and is working to trim $42 million from annual operating expenses. The carrier began flying for Delta in 1984 and became a subsidiary in 2000.

The accident probably won't affect Comair's reorganization under court supervision, said Julius Maldutis, president of Aviation Dynamics Inc. of New York.

No `Technical Failure'

``It was a human failure rather than a technical failure,'' Maldutis said of the crash. ``If it was a maintenance problem, if it was any kind of a technical problem, that could impact the whole bankruptcy process'' because potential financial backers might be scared away.

Delta last week said it would seek bids to fly as many as 143 regional jets, or 21 percent of its fleet, to reduce costs. Among the flights for which Delta seeks proposals are some provided by Comair, which said delays in its own restructuring could result in the loss of some of its current flying.

Comair operates 920 flights a day in about 110 cities in the U.S., Canada and the Bahamas, according to the company's Web site. It served a record 13.1 million customers in 2005. The carrier's fleet consists of 168 CRJ regional jets, in 40-, 50- and 70-seat configurations.

To contact the reporter on this story: Mary Schlangenstein in Dallas at maryc.s@bloomberg.net

Last Updated: August 28, 2006 16:25 EDT