Updated

Two pilots whose plane crashed on takeoff after they turned onto the wrong runway had no trace of alcohol or illegal drugs in their systems, federal safety investigators said Monday.

In updating its investigation of the fiery Aug. 27 crash, which killed 49 people, the National Transportation Safety Board also said no evidence was found of engine failure on Comair Flight 5191.

The Atlanta-bound commuter jet plowed through a perimeter fence and crashed in a field about 1,800 feet from the end of the runway at Lexington's Blue Grass Airport. In the pre-dawn darkness, the crew mistakenly had tried to take off on a runway that was too short.

The sole survivor was James Polehinke, the flight's co-pilot. Polehinke was critically injured but has since shown improvement, and his doctors have said he is expected to survive.

The NTSB said Monday that toxicology testing did not detect any illicit substances or alcohol in Polehinke or the flight's captain, Jeffrey Clay. An over-the-counter decongestant was detected at a low level in Polehinke's blood, it said.

Flight recorders recovered at the scene "have provided valuable information," it said. The NTSB statement gave no detail, but said that investigators "are continuing to extract data from the flight recorders, the air traffic control tape recordings and airport video surveillance cameras."

According to federal investigators, Clay taxied the jet onto the wrong runway before Polehinke took it over and attempted to get it airborne.

During takeoff, the plane accelerated to a maximum of about 137 knots, or roughly 158 mph, the NTSB said.

"The entire sequence took about 36 seconds," the NTSB report said. "The airplane was destroyed by impact forces and a post-crash fire."

Information from the flight data recorder indicates the plane stopped near the end of the shorter runway for about 45 seconds before the flight was cleared for takeoff, the NTSB said.

The lone air traffic controller on duty had cleared the plane to take off from the longer runway, then turned away to perform an administrative task and did not see the crash.

Flight 5191 was the third of three planes scheduled to take off in the early morning of Aug. 27, the NTSB said. The other two planes took off without incident from the longer runway, which is 7,003 feet long. The other runway is half that length.