Federal investigators intensified their efforts on Friday to figure out why a commercial jet plane carrying 144 passengers and five crew members over the northern plains of the United States on Wednesday night overshot its destination by 150 miles.

Combing through the plane’s cockpit voice recorder and the data recorder of Northwest Airways Flight 188, investigators from the National Transportation Safety Board were looking for evidence to explain why the pilots did not respond to radio calls from air traffic controllers.

After the plane had landed safely in Minneapolis, the crew had told the Federal Bureau and airport police that “they were in a heated discussion over airline policy and they lost situational awareness”, the board said, citing information from the Federal Aviation Administration.

The plane’s cockpit voice recorder could capture any conversation between the two crew members on the flight deck, and the flight data recorder would record any manipulation of the controls. An airline spokesman said he did not know the length of the recording period.

The plane, an Airbus A320, was cruising at 37,000 feet when the crew stopped responding, about an hour and five minutes before its scheduled arrival of 8.01 pm.

The plane arrived at 9.15 pm, according to Ed Stewart, a spokesman for Delta Air Lines, which owns Northwest.

The two pilots were suspended from flying pending the outcome of the investigation, Stewart.