This week, the U.S. National Transportation Safety Board (NTSB) released a final report on their investigation of an incident in which both pilots fell asleep during the cruise phase of a go! Airlines flight between Honolulu and Hilo, Hawaii, passing their intended destination before waking up. In their report, the NTSB attributed the incident to "the captain and first officer inadvertently falling asleep during the cruise phase of flight. Contributing to the incident were the captain's undiagnosed obstructive sleep apnea and the flight crew’s recent work schedules, which included several consecutive days of early-morning start times."
The incident occurred on the morning of February 13, 2008. The aircraft, a CRJ-200 (registration N651BR) was operating as go! Flight 1002, a scheduled inter-island passenger service between Honolulu and Hilo. It had completed its climb from Honolulu and was in cruise at FL210 with the autopilot engaged when both pilots "inadvertently fell asleep in the cockpit".
The pilots apparently slept for a period of approximately 15 minutes while the aircraft cruised on autopilot. During that time air traffic controllers and two separate airline crews in the area tried unsuccessfully to reach the incident crew by radio. The aircraft, still cruising at FL210, overflew its destination by about 26 nautical miles before the two pilots awakened, contacted air traffic control, and returned to Hilo for an uneventful landing.
The pilots flew the aircraft on the return leg to Honolulu, after which they reported the incident to the company. About two months later, both pilots were fired by Mesa Air Group, the parent company of go! Airlines.
Here is the link to the synopsis of the NTSB's report about this incident. Here is the link to the detailed full narrative report.