While investigators haven't determined what happened on that Honolulu to Hilo flight, it has ruled out several possibilities.

The NTSB said controllers tried several times to contact the crew unsuccessfully as Flight 1002 overflew Hilo by about 15 miles.

At about 10 a.m., the pilots finally responded and turned back towards Hilo.

KGMB9 has also learned mechanics did check the plane's pressurization system after it landed, as a lack of cabin pressure at high altitudes has been known to cause pilots to blackout. Mechancs found nothing wrong.

They also checked for carbon monoxide poisoning, but the results were negative.

KGMB9 now know that there were 40 passengers on board, plus the two pilots and one flight attendant.

Go!'s parent company, Mesa Airlines, has grounded both pilots while the investigation is underway. The final report could take months.

KGMB9 first broke this story and will have updates on the investigation as we get them.

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