A flight that overshot Hilo International Airport by 15 miles this month had no mechanical problems, according to a preliminary report by the National Transportation Safety Board.
The report makes no conclusion about why the Go airlines flight overshot the airport. Both the board and the Federal Aviation Administration are investigating whether the pilots fell asleep on the Feb. 13 flight from Honolulu to Hilo.
Mechanics checked the plane's pressurization system after it landed; a lack of cabin pressure at high altitudes has been known to cause pilots to blackout. Mechanics found nothing wrong, the Honolulu Star-Bulletin and KGMB-TV reported over the weekend.
They also checked for carbon monoxide poisoning, but the results were negative.
Flight 1002 left Honolulu at 9:16 a.m. but drifted off course during the 214-mile trip and had to turn back to get to the Hilo airport. The flight landed safely.
Air traffic controllers were unable to contact the cockpit for 25 minutes. There were 40 passengers on board, plus two pilots and one flight attendant.
Go's parent company, Mesa Airlines, has grounded both pilots during the investigation. The final NTSB report could take months.
The NTSB and the FAA are conducting separate investigations into whether the captain and first officer fell asleep, said FAA spokesman Ian Gregor.
If the pilots did fall asleep while the plane was on autopilot, FAA rules carry penalties ranging from a warning letter to license suspension or revocation.
Mesa launched Go airlines in June 2006. It is the state's fourth largest carrier, flying 50-seat Bombardier CRJ-200 aircraft.