The pilots, Capt. Timothy Cheney, 54, of Gig Harbor, Wash., and First Officer Richard Cole, 54, of Salem, Ore., , saying in documents filed late last month with the National Transportation Safety Board that controllers didn't follow air traffic rules and practices.
Cheney and Cole are appealing the revocation of their licenses. They admit they were using laptops in the cockpit to discuss company policies as they failed to answer radio calls.
American air traffic controllers tried in vain to reach the Northwest flight for 77 minutes, Sallinger notes.
The final communication before the radio blackout was from the Denver air traffic control center.
FAA's Tapes and Transcripts for Northwest Flight 188
But when contact was finally resumed, the pilots turned up on a different frequency, speaking with controllers in Winnipeg, Canada.
"You reach down, you dial in, and perhaps you didn't turn the knob one more click and suddenly, you find yourself on a completely different frequency than the one you were assigned," aviation safety consultant Steve Cowell told CBS News.
But a spokesperson for the FAA told Sallinger, "We found this out afterwards, about Winnipeg. There was no way the controllers would know, and did know, how the pilots happened to come back up on that frequency."
CBS News Correspondent Nancy Cordes, who covers aviation, observes that, "Pilots have to switch frequencies all the time, so it's not that unusual that, from time-to-time, a pilot might switch to the wrong frequency. Still, after these pilots hadn't heard from anyone for about half-an-hour, they should have grown suspicious because, ordinarily, pilots flying over the continental U.S. don't go, say, ten-to-fifteen minutes without hearing from a controller."
Controllers in the U.S. were, says Cordes, "making educated guesses" when the pilots were unresponsive. "They tried to reach the pilots on their last known frequency, they tried to reach the pilots on the frequency they should have been on. There are dozens and dozens of frequencies. There's no way they would have known the pilots happened to be on this random Canadian frequency.
"But, at the same time, if the pilots had been monitoring their instruments, they would have known that they were approaching Minneapolis and that it was time to land. They don't need an air traffic controller to tell them that. And the fact that they overshot their destination without ever trying to descend indicates that, not only were they not monitoring their radios, but they weren't monitoring their instruments, as well."