Oct. 22 (Bloomberg) -- U.S. safety investigators are reviewing a flight by Delta Air Lines Inc.’s Northwest unit that overshot its destination at the Minneapolis airport yesterday after losing contact with air traffic controllers.

The pilots said they were “in a heated discussion over airline policy” and “lost situational awareness,” flying northeast about 150 miles past the airport, the National Transportation Safety Board, which is investigating the incident, said today in a statement.

Pilot distraction has drawn attention from government safety officials who worry the phenomenon can have deadly results. The NTSB has examined the possibility that distraction contributed to a Pinnacle Airlines Corp. crash in February near Buffalo that killed 50 people.

Overshooting an airport is “extremely worrisome” because the pilots must have missed repeated calls from air traffic controllers on their headsets, said John Nance, a retired Air Force and commercial airline pilot with 40 years of flying, who runs a Seattle aviation consulting firm under his name.

“For this to happen, they would have had to turn down their radios so low, or even worse, took them off, and nobody was listening for an extended period of time,” Nance said. “I’ve been in many heated arguments in the cockpit, and the professional thing to do is wait until you’re on the ground. There’s no excuse for this.”

The Wall Street Journal reported the pilots may have fallen asleep. The safety board doesn’t “have any evidence of that yet at this point,” Keith Holloway, an NTSB spokesman, said in an interview.

Flying Over Wisconsin

The flight from San Diego on an Airbus A320 overshot the Minneapolis airport and flew over Wisconsin before turning around and heading back to its destination, according to Houston-based flight-tracking service FlightAware.com. The flight, Northwest 188, landed at 8:54 p.m. local time, according to FlightAware.com.

The plane passed the Minneapolis airport at 7:58 p.m. local time and didn’t reestablish communications with air traffic controllers until 8:14 p.m., 16 minutes later, the NTSB said.

Minneapolis-St. Paul airport officials dispatched police to meet the plane when it landed and “make sure there was no one on board that caused the problem,” said Patrick Hogan, a spokesman for the airport.

The plane was carrying 144 passengers and five crew members, Kent Landers, a spokesman for Delta, said in an interview, declining to comment on the pilots’ ages, flight hours or years of experience.

“The safety of our passengers and crew is our top priority,” he said.

Relieved From Flying

The pilots have been relieved from flying until the NTSB and Delta complete investigations, Landers said in an e-mailed statement. Delta won’t comment further on what happened in the cockpit until it and the agencies complete their investigations, Landers said.

“We’ll be working with the NTSB to figure out what happened,” Federal Aviation Administration spokeswoman Laura Brown said in an interview.

Kelly Regus, a spokeswoman for the Delta chapter of the Air Line Pilots Association, declined to comment.

Pilots are constantly trained in awareness and the risks of distraction, Embry-Riddle Aeronautical University Director of Aviation Safety David Zwegers said in an interview.

“We make every effort to assure our students and instructors dedicate 100 percent in the cockpit to safety in the flight” at Embry-Riddle, based in Daytona Beach, Florida, Zwegers said. “That includes minimizing distractions. That includes situational awareness and good habits and training.”

At 37,000 Feet

Because the pilots were flying at 37,000 feet, according to the NTSB, they were not bound by federal restrictions on non- flight-related conversation below 10,000 feet, Zwegers said.

At a hearing in May, a cockpit-distraction researcher from the National Aeronautics and Space Administration told the NTSB that the pilots’ conversations about icing during the flight by Pinnacle’s Colgan unit diverted the crew’s attention from understanding what they needed to do as the plane approached the Buffalo airport in February.

Pilot distraction played a role in a 2005 Southwest Airlines Co. accident in which a plane slid off the runway during a Chicago snowstorm and onto a roadway, killing a 6-year- old boy riding in his family’s car.

The NTSB concluded that the pilots didn’t deploy thrust reversers more quickly to slow the plane because they were distracted by a new company landing procedure they were using for the first time. The board partly blamed Southwest management for failing to give pilots adequate time to become familiar with the procedure.

To contact the reporters on this story: Angela Greiling Keane in Washington at Mary Jane Credeur in Atlanta at mcredeur@bloomberg.net.

Last Updated: October 22, 2009 17:23 EDT