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.