The NTSB has launched an investigation into an incident yesterday in which a Northwest Airlines Airbus A320 overflew its destination–Minneapolis-St. Paul International/Wold-Chamberlain Airport (MSP)–apparently as the crew engaged in a “heated discussion” over airline policy.

ATC lost radio contact with the flight at 5:56 p.m. Mountain Daylight Time, as Northwest Airlines Flight 188 cruised at 37,000 feet. The flight carried 147 passengers and an unknown number of crew from its departure airport, San Diego International. At 7:58 p.m. Central Daylight Time, the airplane flew over the destination airport and continued northeast for some 150 miles.

The MSP center controller re-established communications with the crew at 8:14 p.m. and reportedly stated that the crew had become distracted. At that time they requested a return to MSP.

According to the FAA, the FBI and airport police interviewed the crew upon their return to MSP. The Safety Board plans to schedule its own interview with the crew. Investigators have secured the airplane’s CVR and FDR, which they have sent to the NTSB’s Washington, D.C. headquarters for analysis.