The Federal Aviation Administration on Tuesday revoked the licenses of the two Northwest Airlines pilots who overshot their Minneapolis destination by 150 miles.

The pilots — Timothy Cheney of Gig Harbor, Wash., the captain, and Richard Cole of Salem, Ore., the first officer — told safety investigators they were working on their personal laptop computers and lost track of time and place.

The pilots, who were out of communications withair traffic controllers for 91 minutes, violated numerous federal safety regulations in the incident last Wednesday night, the FAA said in a statement. The violations included failing to comply with air traffic control instructions and clearances and operating carelessly and recklessly, the agency said.

"You engaged in conduct that put your passengers and your crew in serious jeopardy," FAA regional counsel Eddie Thomas said in a letter to Cheney. Northwest Flight 188 was not in communications with controllers or the airline dispatchers "while you were on a frolic of your own. ... This is a total dereliction and disregard for your duties."

A similar letter was sent to Cole.

Phoenix Arizona Aviation Law Expert Charlie Brewer says it's likely their laptops blocked the navigation instruments.