Washington  - Two airline pilots have had their licenses withdrawn after they overflew their destination and were lost for more than an hour while they were toying with their personal laptops, US federal aviation officials announced in Washington late Tuesday.

The pilots' behaviour had been negligent and careless, the officials said, adding the pilots had violated a series of aviation regulations, including failing to respond to instructions by traffic controllers.

The Northwest Airlines incident on October 21 had triggered a security alert in the White House situation room. Two military jets were scrambled in case of a possible security threat.

According to its initial investigation and interviews with the pilots, ages 53 and 54, the National Transportation Safety Board (NTSB) said it appeared the two pilots, aged 53 and 54, "lost track of time" as they used their personal laptop computers.

The pilots said they had been absorbed in a new programme for "airline crew flight scheduling procedures" that had become complicated after last year's merger between Delta and Northwest Airlines.

They had been discussing the schedules so intensely that they even failed to respond to radio and cell phone calls for more than an hour, they said.

The Airbus A320 had departed from San Diego with 147 passengers plus crew, and landed safely after flying 160 kilometres past Minneapolis on autopilot at an altitude of 12,000 metres. (dpa)