Air traffic controllers, other pilots and even a flight attendant on an intercom tried desperately to talk to two errant pilots as their passenger plane flew 150 miles (240 kilometers) past its destination before turning back.
Unable to raise Northwest Airlines Flight 188, police and FBI agents on the ground were preparing for the worst and the Air National Guard put fighter jets on alert at two locations as the drama unfolded Wednesday night.
Pilots from two other planes in the vicinity were finally able to reach the plane using a different radio frequency, a controllers' union spokesman said. A flight attendant in the cabin also was able to contact them by intercom, said a source close to the investigation who was not authorized to talk publicly and spoke on condition of anonymity. By that time, the Airbus A320 was over Eau Claire, Wisconsin, past their Minnesota destination, and the pilots had been out of communication with air traffic controllers for more than an hour.
The crew told authorities they were distracted during a heated discussion over airline policy, said the National Transportation Safety Board, which is investigating the incident that unfolded over two upper Midwest states.
Investigators do not know yet whether the pilots may have fallen asleep, but fatigue and cockpit distraction will be looked into, NTSB spokesman Keith Holloway said Friday.
The plane's cockpit voice and flight data recorders were expected to be delivered to the board's Washington office Friday, Holloway said.
"Hopefully we'll know more after that," Holloway said.
But investigators may have a hard time determining what happened. They say the plane had an older model voice recorder that records only 30 minutes at a time. It is likely the recorder captured only the last 30 minutes of the flight — much of that time after the pilots had realized their error and turned the plane back. Newer models record for two hours.
Investigators probably will not interview the pilots until next week, Holloway said. The pilots have been suspended from flying by Delta Air Lines, which acquired Northwest last year, while the airline also investigates.
The plane, en route from San Diego, California, with 144 passengers and a crew of five, passed over its destination of Minneapolis at 37,000 feet just before 8 p.m. local time. Contact was not established with controllers until 14 minutes later, NTSB said.
Air traffic controllers in Denver, Colorado, had been in contact with the pilots as they flew over the Rocky Mountains, FAA spokeswoman Laura Brown said. But as the plane got closer to Minneapolis, she said, "the Denver center tried to contact the flight but couldn't get anyone." That was just before 8 p.m.
Denver controllers notified their counterparts in Minneapolis, who also tried to reach the crew without success, Brown said.
Controllers suspected that Flight 188's radio may still have been tuned to a frequency used by Denver controllers even though the plane had flown beyond the reach of that region's controllers, said Doug Church, a spokesman for the National Air Traffic Controllers Union. Controllers worked throughout the incident with the pilots of other planes, asking them to try to raise Flight 188 using the Denver frequency, he said
That was unsuccessful until two pilots working with Minneapolis controllers finally got through just before the plane turned around, Church said. Minneapolis controllers do not have the capability of using the Denver frequency, but pilots do, he said.
After reestablishing contact with the plane, controllers asked the pilot in charge to execute a series of turns to show he was in control of the aircraft, Church said.
"Controllers have a heightened sense of vigilance when we're not able to talk to an aircraft. That's the reality post- 9/11," he said. He was speaking about the Sept. 11, 2001, attacks on the United States when terrorists captured four airliners and crashed them into buildings or the ground.
Passenger Lonnie Heidtke said he did not notice anything unusual before the landing except that the plane was late.
The flight attendants "did say there was a delay and we'd have to orbit or something to that effect before we got back. They really didn't say we overflew Minneapolis. ... They implied it was just a business-as-usual delay," said Heidtke, a consultant with a supercomputer consulting company based.
Once they were on the ground, the plane was met by police and FBI agents. Passengers retrieving their luggage from overhead bins were asked by flight attendants sit down, Heidtke said. An airport police officer and a couple of other people came on board and stood at the cockpit door, talking to the pilots, he said.
"I did jokingly call my wife and say, 'This is the first time I've seen the police meet the plane. Maybe they're going to arrest the pilots for being so late.' Maybe I was right," Heidtke said.
The pilots' explanation that they were distracted by shop talk "just doesn't make any sense," said Bill Voss, president of the Flight Safety Foundation in Alexandria, Virginia. "The pilots are saying they were involved in a heated conversation. Well, that was a very long conversation."
The FAA is updating rules governing how many hours commercial pilots may fly and remain on duty. The NTSB also cautioned government agencies this week about the risks of sleep apnea contributing to transportation accidents.
Associated Press Airlines Writer Joshua Freed and AP writers Steve Karnowski in Minneapolis and Dave Koenig in Dallas, Texas, contributed to this report.
On the Net:
FlightAware.com tracking of Northwest Flight 188: http://bit.ly/2QV9hX
National Transportation Safety Board www.ntsb.govCopyright © 2014, Los Angeles Times