Because the aircraft has an old cockpit voice recorder, the world may never know why the pilots of Northwest Flight 188 lost contact with ground control for 78 minutes. The recorder on the Airbus A320 has a maximum memory of 30 minutes, after which it tapes over itself. So investigators can listen only to the last half-hour of the flight—after the pilots has re-established contact with air traffic controllers and gotten back on course.
Delta, owner of Northwest, has suspended the pilots pending multiple investigations, the Wall Street Journal reports. Meanwhile, Air National Guard F-16s in Wisconsin were ready to shoot the plane out of the sky on NORAD's orders. "As a force of last resort, NORAD is always prepared to do whatever is necessary," a rep for the defense agency tells ABC News.