In a harshly worded rebuke of the two pilots of the wayward Northwest Airlines Flight 188, the Federal Aviation Administration on Tuesday revoked their licenses, saying they "carelessly and recklessly" put their passengers and crew in jeopardy.

"NW188 was without communication with any air traffic control facility for a period of 91 minutes while you were on a frolic of your own," the FAA said in a letter to the pilots. "You were disengaged and impervious to the serious threat to your own safety, as well as the safety of the people for whom you are responsible."

Previously, federal investigators had laid out a timeline that indicated the plane was out of radio contact for only about 75 minutes.

Asked why the licenses were revoked while the investigation is still underway, FAA spokeswoman Laura Brown said, "Whenever we think there is reason to take immediate action, we would do so."

The pilots, Capt. Timothy B. Cheney, 53, of Gig Harbor, Wash., and First Officer Richard I. Cole, 54, of Salem, Ore., dropped out of radio communications on the 1,530-mile San Diego-to-Minneapolis flight last Wednesday evening because they were engrossed in their personal laptop computers, the National Transportation Safety Board said Monday. They have 10 days to appeal the emergency revocations to the NTSB. If that fails, they can apply for new certificates after one year.

Neither man returned phone calls seeking comment.

Asked to comment on the revocations, Delta Air Lines, parent of Twin Cities-based Northwest, would say only that the pilots remain suspended. Company policy prohibits use of laptops on the flight deck.

The pilots overshot the Minneapolis-St. Paul International Airport (MSP) by about 100 miles before turning around and landing safely. The flight had 144 passengers and five crew members.

The pilots said they lost track of time while using their laptops to confer about airline scheduling procedures, the NTSB said in its report of initial findings. The pilots said they removed their headsets but were able to hear radio chatter.

Air traffic controllers and airline officials repeatedly tried to reach them through radio and data contact. The situation grew so alarming that four fighter jets were on standby to track down the plane to see if it had been hijacked or if the pilots were incapacitated.

"Not only did you not comply with clearances on instructions, you did not even monitor the aircraft's air-ground radios," the FAA said in its letter.

'We got distracted'

About 8:14 p.m. last Wednesday, the pilots contacted MSP, saying: "We got distracted and we've overflown MSP, we are overhead EAU [Eau Claire] and would like to make a 180" and plan an arrival.

The revocation letter also indicated the plane's fuel supply could have become an issue. The flight's "planned fuel summary" was based on the flight beginning its descent into MSP about 2 hours and 50 minutes into the flight, which would have been about 7:50 p.m.

In fact, the plane flew over the Twin Cities airport at 37,000 feet at 8 p.m., still out of contact with anyone on the ground. After its trek over Wisconsin, the plane turned around and landed at 9:05 p.m.

The revocations come less than a day after the union that represents the pilots scolded federal investigators for releasing "information to be sensationalized in the press" from the two aviators within days of the inquiry beginning.

In a statement released late Monday, Delta Master Executive Council Chairman Lee Moak said, "We do not condone the abandonment of due process that will result from a rush to judgment; instead we implore all interested parties to move with deliberate and unemotional professionalism as the events surrounding this incident are investigated."

Staff writer Paul Walsh contributed to this report. Suzanne Ziegler • 612-673-1707