Passengers on Go! Airlines flight 1002 took off on time last Wednesday morning expecting a short flight.
But they got more than they paid for, reports CBS News correspondent Ben Tracy.
"When I noticed we weren't descending I told my wife - she was sitting to my left - I mentioned to her, 'I think something's kind of weird in this flight pattern,'" said passenger Derrick Lining.
Weird, because the pilots on the flight from Honolulu, which normally takes 30 minutes to reach Hilo, overshot their landing by 15 miles before finally turning around. Air traffic controllers had tried to reach them for 25 minutes, but heard nothing back.
"We're investigating whether the pilot and co-pilot of Go! Airlines inter-island flight fell asleep while the plane was in the air between Honolulu and Hilo," said Ian Gregor of the Federal Aviation Administration.
Barry Schiff is an airline-safety expert who says pilot fatigue is a bigger problem than the flying public knows.
"I don't think the public has any idea how tired these pilots are," Schiff said. "But of course they get a cheap ticket, don't they?"
A passenger on a Go! flight said: "Any time you hear of a pilot going to sleep on a flight - especially the flight you're on - yeah, it makes you real nervous."
A statement from Mesa Airlines read: "We are cooperating fully. We have no further comment."
Mesa Airlines, which runs Go! Airlines, said in a statement today that it is cooperating with the FAA.
Pilots for Mesa Airlines have complained in the past about tight schedules and staffing shortages.
The FAA plans to interview the pilots of this flight to find out exactly what went wrong.
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