WASHINGTON — Two go! airline pilots fell asleep while flying from Honolulu to Hilo in February, cruising past their destination for 18 minutes before waking up and returning for a safe landing, federal investigators confirmed yesterday.

That incident and an accident in Traverse City, Mich., last year highlight the need for new rules to prevent crashes attributed to the long hours that pilots routinely work, the National Transportation Safety Board said.

Crashes linked to fatigue have killed 249 people since 1997, according to NTSB records.

"It's an insidious issue," said NTSB Chairman Mark Rosenker. "Many times the pilots themselves don't recognize that they are fatigued when they get into that cockpit."

The NTSB voted to recommend that federal aviation regulators and airlines use fatigue studies to rewrite the rules for how long pilots can legally fly. Currently, federal law allows pilots to work up to 16 hours a day, including up to eight hours behind the controls, and loopholes allow longer days in some situations.

Air-traffic controllers frantically radioed go! Flight 1002 from Honolulu to Hilo for 18 minutes on Feb. 13, but got no response from the pilots, said NTSB investigator Jana Price.

In the safety board's first disclosure of details from the investigation, Price said both pilots "unintentionally fell asleep" as the Bombardier CRJ-200 jet flew at 21,000 feet. The jet carried 40 passengers.

The two pilots had been flying together for three arduous days "that involved early start times" and a "demanding" sequence of short flights, Price said.

Since the incident, the captain had been diagnosed with severe obstructive sleep apnea, she said. Apnea causes people to repeatedly wake at night and has been linked to poor work performance and accidents.

The pilots, whose names have not been released, were fired.

The parent company of go!, Mesa Air Group Inc., did not return a phone call seeking comment yesterday.

FATIGUE IN MICHIGAN

In a separate investigation, the NTSB concluded that a regional airline crash last year in Traverse City was probably triggered by fatigue. Pinnacle Airlines Flight 4712 skidded off the end of a snowy runway early on the morning of April 12, 2007. No one was injured.

The NTSB found that the pilots of the Bombardier CRJ-200 should never have attempted the landing.

The runway was too slick to land under the airline's rules, but the pilots failed to perform a basic landing calculation and missed other warning signs that the weather was deteriorating.

The accident happened after the pilots had worked 14 hours. The cockpit recorder overheard the pilots yawning and the captain made repeated references to being tired, the NTSB found.

The NTSB has been calling for reform of pilot work rules for decades. Several attempts to rewrite pilot work rules have failed in the face of opposition from airlines and pilot groups.

The Pinnacle overrun "was the result of a series of actions and events involving multiple parties and rapidly changing weather conditions in an extremely short time," said Joe Williams, a spokesman for the Memphis, Tenn.-based airline. "We apologize for any impact on our customers."

The NTSB's recommendations now go to the Federal Aviation Administration, which would develop specific steps to guard against pilot fatigue, including rules on scheduling work shifts.

"We've got to do something about it, otherwise we get catastrophic results," Rosenker said.

SAFETY SYMPOSIUM

The FAA is scheduled to hold a symposium next week on managing aviation fatigue with representatives from air carriers, labor unions, aviation associations and scientists. The NTSB, Defense Department, NASA and other agencies will participate.

FAA spokeswoman Laura Brown said it will respond to the NTSB about its recommendations within three months.

But Brown said many airlines already have training for their pilots on fatigue.

"We will take a look at the (NTSB) recommendations and move forward based on the information we get as a result of that conference," Brown said.

FAA investigators have completed their investigation of the go! incident but the report has not been released, the FAA said last week. If there are FAA sanctions, they could range from a warning letter to suspension to revocation of the pilots' licenses.

Ian Gregor, an FAA spokesman, pointed out that the Go! Pilots had 15 hours of rest before their Hilo flight.

A Shuttle America Corp. flight overran a snowy runway in Cleveland on Feb. 18, 2007. The NTSB later found the captain had insomnia, and he reported he had been awake 31 of the previous 32 hours, Price said. The 74 passengers and crew members weren't hurt.

The board also cited a Corporate Airlines flight that crashed on Oct. 19, 2004, killing 13 people, after the pilots didn't follow procedures and flew the plane too low into trees. Fatigue probably contributed to the accident in Kirksville, Mo., the NTSB found.

The Air Line Pilots Association said the current regulations do not effectively deal with the issue of fatigued pilots.

"There is only so much you can ask a human body to do," said Rory Kay, head of the group's air safety program.

USA Today, Bloomberg News Service and Advertiser staff writers Dennis Camire and Mike Leidemann contributed to this report.