The US NTSB (National Transportation Safety Board) has said it is investigating a flight that overshot its destination by 150 miles. It was reported, that the pilots got into a "heated discussion" on airline policy.
The NTSB said Wednesday evening the Airbus A320 became a "no radio communications" flight on Wednesday evening as it travelled at 37,000 feet (11,300 meters) from San Diego, California, prompting fears it had been hijacked.
The Minneapolis Star-Tribune reported that four military fighter jets were readied to chase down the plane before contact was reestablished.
The flight was carrying 147 passengers and an unknown number of crew and was supposed to land at Minneapolis-St Paul International/Wold-Chamberlain Airport, AFP reports.
Guardian.co.uk quoted NTSB spokesman as saying, "They were in a heated discussion over airline policy and they lost situational awareness."
When the pilots got their "situational awareness" back they turned the Airbus A320 around and landed it safely on Wednesday evening, apparently without any of the 144 passengers realising they had taken a roundabout route.
Ground controllers lost contact with the pilots just before 7pm and radio contact was not re-established for more than an hour. The Federal Aviation Administration notified the military, which put fighter jets on alert at two locations.
The flight was scheduled to land at 8.01pm local time but eventually arrived at 9.15pm, according to Ed Stewart, a spokesman for Delta Air Lines, which owns Northwest. Delta has suspended the pilots while it carries out an internal investigation, and the cockpit voice recorder and flight data recorder were being sent to Washington for analysis, guardian.co.uk reports.
It was also reported, airport police then boarded the plane to make sure the loss of radio contact wasn't the result of criminal activity, Patrick Hogan, an airport spokesman, told the Pioneer Press.
The military jets that were on alert -- which is routine procedure -- never made it to the air, as the pilots made contact before it came to that. The pilots were interviewed upon landing, and investigators from the NTSB plan to review data from the plane's digital flight-data recorder, "which could offer clues as to what transpired during the period when airport controllers lost contact with the plane," the WSJ writes. "Initially, investigators focused on the possibility that both pilots might have fallen asleep in midflight, but later indications were that the crew may have lost track of where they were and then failed to swiftly notify controllers about their lapse."
This incident takes place as pilot fatigue is a hot topic among the FAA, airlines and pilots unions and is likely to stir up that debate, USA Today reports.