Two Northwest Airlines pilots who flew 150 miles past their destination because they were focused on laptop computers instead of cockpit displays may have opened a new avenue of concern for safety regulators — distracting personal electronic devices on the flight deck.

The pilots of Northwest flight 188 told the National Transportation Safety Board that they were so engrossed in a complicated new crew-scheduling program on their laptops — a cockpit violation of airline policy that could cost them their licenses — that they lost track of time and place for more than an hour until they were brought back to alertness by a flight attendant on an intercom.

By then, the Airbus A320 with its 144 passengers and five crew members had cruised past its Minneapolis destination and was over Wisconsin, at 37,000 feet.

The pilots — Richard Cole of Salem, Ore., the first officer, and Timothy Cheney of Gig Harbor, Wash., the captain — denied they had fallen asleep as aviation experts have suggested, the safety board said in recounting investigators' interviews with the men over the weekend.

SLIDESHOW: Northwest Airlines Plane Mystery

Instead, Cole and Cheney said they both had their laptops out while the first officer, who had more experience with scheduling, instructed the captain on monthly flight crew scheduling.

The incident last Wednesday night comes only a month after Transportation Secretary Ray LaHood held a meeting in Washington on distracted driving, bringing together researchers, regulators and safety advocates in response to vehicle and train accidents involving texting and cell phone use.

While the Northwest pilots were able to turn their plane around and land safely in Minneapolis, pilots and aviation safety experts said the episode is likely to cause NTSB and the Federal Aviation Administration to take a hard look at the use of laptops and other personal electronic devices in the cockpit.

There are no federal rules that specifically ban pilots' use of laptops or other personal electronic devices as long as the plane is flying above 10,000 feet, said Diane Spitaliere, a Federal Aviation Administration spokeswoman.

"I think it depends upon how it's being used," Spitaliere said.

Delta Air Lines Inc., which acquired Northwest last year, said in a statement that using laptops or engaging in activity unrelated to the pilots' command of the aircraft during flight is strictly against the airline's flight deck policies. The airline said violations of that policy will result in termination.

Several other airlines said they have similar policies. At Southwest Airlines, for example, "our pilots are not allowed to use any electronic device unless it's approved by the FAA and supplied by Southwest," said Brandy King, a spokeswoman for the airline. "That means no laptops, no cell phones, no PDAs."

The reality, said pilots, is that it goes on quite a bit during the sometimes boring cruise phase of a flight, as happened with the Northwest pilots.

"It's commonly done," said Jack Casey, a former commercial airline pilot for 34 years and now a safety consultant. Although, he said, it is unusual for both pilots to use their laptops at the same time. Typically, while one pilot flies the plane, the other pilot might use a laptop or some other device, he said.

That doesn't make it safe, Casey said, and it probably violates FAA regulations that broadly prohibit activities in the cockpit that don't relate to flying the plane.

"I would be very surprised if the FAA doesn't decide to review what's going on in the cockpit in terms of the new electronic world that we live in," Casey said. "The conversations have only just begun on this thing."

Indeed, the NTSB's release wasn't even cold when Sen. Al Franken, D-Minn., called for a ban on the use of personal laptops in the cockpit.

"We don't tolerate texting while driving and we're certainly not standing for it while flying," Franken said in a statement.

A number of aviation experts have suggested it was more plausible that the pilots had fallen asleep during the San Diego-to-Minneapolis flight.

Air traffic controllers in Denver and Minneapolis repeatedly tried without success to raise the pilots by radio. Other pilots nearby tried reaching the plane on other radio frequencies. Their airline tried contacting them using a radio text message that chimes.

Authorities became so alarmed that National Guard jets were readied for takeoff at two locations and the White House Situation Room alerted senior officials, who monitored the airliner as the Airbus A320 flew across a broad swath of the mid-continent out of contact with anyone on the ground.

"It's inexcusable," former NTSB Chairman Jim Hall said. "I feel sorry for the individuals involved, but this was certainly not an innocuous event — this was a significant breach of aviation safety and aviation security."

The Delta pilots union pointed out that at no time were the passengers, crew or aircraft in danger, and cautioned against a "rush to judgment."

"I strongly encourage all parties not to reach a hasty conclusion, " Capt. Lee Moak, chairman of Delta's pilots' union, said in the statement issued late Monday. "We stand firmly behind the crew's right to due process."

Delta has suspended the two pilots pending an investigation into the incident. The FAA is also investigating and has warned Cheney and Cole their pilot licenses could be suspended or revoked.

Cheney and Cole are both experienced pilots, according to the NTSB. Cheney, 53, was hired by Northwest in 1985 and has about 20,000 hours of flying time, about half of which was in the A320. Cole, 54, had about 11,000 hours of flight time, including 5,000 hours in the A320.

Both pilots told the board they had never had an accident, incident or violation, the board said.

The pilots acknowledged that while they were engaged in working on their laptops they weren't paying attention to radio traffic, messages from their airline or their cockpit instruments, the board said. That's contrary to one of the fundamentals of commercial piloting, which is to keep attention focused on monitoring messages from controllers and watching flight displays in the cockpit.

"It is unsettling when you see experienced pilots who were not professional in flying this flight," said Kitty Higgins, a former NTSB board member. "This is clearly a wakeup call for everybody."

The Northwest Pilots who overshot a Minnesota runway by 150 miles last week told investigators they were using their personal laptops in the cockpit, a violation of company policy, according to a National Transportation Safety Board advisory.

The two pilots, interviewed separately on Sunday, told investigators they lost track of time when they used their laptops while in a “concentrated period of discussion” about the new monthly crew flight scheduling system.

The system reportedly changed after the Northwest-Delta merger.

The pilots told NTSB officials that they had not been monitoring the airplane or calls from Air Traffic Control at that time, according to the report.

Both pilots said they heard conversation on the radio, but failed to notice messages that were sent by dispatchers. It wasn’t until a flight attendant called the pilots about five minutes before the flight was scheduled to land that they realized they had passed the airport, according to the report.

Fighters from two North American Aerospace Defense Command sites were put on alert for the plane when it was not responding to radio calls from the Federal Aviation Administration, NORAD reported.

The alert was called off once the FAA re-established communications with the pilots, according to NORAD.

Both pilots told investigators that they did not fall asleep nor have a heated argument, according to the advisory.

The Wall Street Journal reported that additional factors also may have contributed to protracted radio silence.

NTSB spokesman Keith Holloway said investigators interviewed the pilot and co-pilot in person in Minneapolis.

The agency also interviewed the three flight attendants on Monday, Fox News has learned.

Northwest Airlines is cooperating and conducting its own internal investigation, said Chris Kelly, a spokesman for Northwest Airlines' parent company, Delta Air Lines Inc.

Air traffic controllers tried for more than an hour Wednesday night to contact the Airbus A320 Minneapolis-bound flight, which later turned around and landed safely. There were 144 passengers on the flight.

The NTSB said it will continue its investigation.