Brent Bjorlin and his fellow airline passengers didn't have a clue something had gone wrong at 37,000 feet until federal officials with badges and guns boarded the Northwest plane after it landed in the Twin Cities on Wednesday night.

As passengers prepared to leave, flight attendants told them to sit back down, Bjorlin said. Eventually, he and the others filed out, walking past security officials standing outside the closed cockpit door and still others on the jetway and at the gate.

"It looked like it was a big deal," said Bjorlin of St. Michael, Minn.

It wasn't until the next day that he and the others found out that Northwest Flight 188 from San Diego had overshot Minneapolis-St. Paul International Airport by 150 miles, winding up in Wisconsin before turning around to land safely at MSP. Federal officials say the pilots apparently became distracted. Military jets had been on standby to track down the jet after it dropped out of radio communication for about 75 minutes.

"When you hear that fighter jets were ready to scramble, that just gets you really mad," said passenger Scott Kennedy.

In hindsight, passengers say, the wayward flight to Wisconsin may explain why the flight seemed to "drag on," the usual pilot updates were nonexistent and why a flight attendant's "unusual comment" now makes perfect sense.

Some passengers worried about making their connecting flights, Bjorlin said. When a passenger asked when the plane was expected to land, the attendant returned 10 minutes later and said, "'I have no idea when we're going to get to the terminal,'" he said.

Eventually, the pilot announced that the crew was waiting for clearance and would be landing soon, said Anne Kroshus of Woodbury. But the expected arrival time came and went. "It was bizarre," she said. "It certainly didn't feel like we were circling."

"I hate flying," Kroshus said. So to find out that the plane lost radio contact and missed its mark "really freaks me out," she said. "Planes are scary enough as it is, and [now I find out] that my safety was completely on the line by their negligence."

The National Transportation Safety Board (NTSB) is investigating, and Delta Air Lines, which operates Northwest Airlines, has suspended the pilot and co-pilot of the Airbus A320. Delta said Flight 188 had 144 passengers and five crew members.

The pilots didn't respond to controllers' repeated efforts to contact them from about 7 p.m., when the plane was over western Kansas, until 8:14 p.m. when the plane was in Wisconsin, about 150 miles northeast of MSP. The plane flew over the Twin Cities at 7:58 p.m.

The situation grew increasingly alarming from a safety and security standpoint because the pilots could have been in distress or the plane hijacked, said FAA spokesman Tony Molinari.

"When you aren't speaking to a commercial airliner, that's a big issue for us," he said. "We see them on the radar, but not being able to talk to them is a problem."

Control towers in Denver and Minneapolis tried to contact them, as did Northwest, via its dispatch network.

Jets on the verge of taking off

The military had four fighter jets ready to chase down the plane, said Michael Kucharek, a North American Aerospace Defense Command spokesman.

The jets were on the "edge" of taking off but did not have to because communication with Flight 188 was reestablished. "You never know what the situation is, why they're not in contact," he said.

The fighter pilots would have flown by the plane to see whether someone was in control or tried "other methods" to get the attention of the pilots. "Usually when you see fighters off your wing, it gets your attention," he said, noting that the jets get called into action with commercial planes a handful of times each year.

The FAA said the FBI and airport police interviewed the crew, who said they "were in a heated discussion over airline policy, and they lost situational awareness." The crew requested that the plane be allowed to return to MSP. The NTSB is scheduling an interview with the crew.

The Wall Street Journal reported Thursday that the NTSB is investigating whether the pilots fell asleep.

NTSB spokesman Keith Holloway said it would be "speculative" to say whether that's what happened. "We don't know. We are looking into everything," he said, adding that nothing has been ruled out. Molinari said he could neither confirm nor deny the report, saying the investigation is in the hands of the NTSB.

The cockpit voice recorder and flight data recorder are being sent to the NTSB laboratory in Washington, D.C.

"The safety of our passengers and crew is our top priority," Delta said in a statement. "We are cooperating with the FAA and NTSB in their investigation as well as conducting our own internal investigation. The pilots have been relieved from active flying pending the completion of these investigations."

The Air Line Pilots Association declined to comment due to the NTSB investigation.

Flight seemed to drag on

Passengers said they received no word in flight that the plane was off course. Bjorlin said the flight was delayed 45 minutes in San Diego, and then once they were in the air, the trip seemed to "drag on," he said.

When the plane experienced a bit of turbulence early in the trip, the pilot announced he would fly higher, said passenger Kennedy. But after that, there was no banter from the cabin.

"The day before, I took the same direct flight, and the guy kept coming on and saying, 'If you look out to your left, you'll see the Rockies.' The guy was, like, talkative. I've had that many, many times," Kennedy said. "It was very quiet. ... I just figured that they're professionals, and we're covered. No problem."

Bjorlin said it's disconcerting that the plane could be that far off course and lose radio contact, and it makes him wonder what the pilots were doing and whether the plane was in any danger.

"Either way, every one of us on that flight want the extra miles put on our perks card," he said.

Staff writer Paul Walsh contributed to this report. • 612-673-1707 • 612-673-4595