Computers on board aircraft have made flying safer, but when they encounter errors they can create turmoil. Engineers are pressing ahead with the automation of aircraft, but pilots warn that efforts to computerize jets are going too far and that diminished human control could create dangerous situations.

Ben Cave was starting to get bored. The Australian had been sitting in his seat for more than three hours, and he still had two hours left before the Qantas jet was scheduled to touch down in Perth.

The Airbus A330 was flying at a cruising altitude of 11,278 meters (37,000 feet). The calm of modern jet travel, accentuated by the monotonous drone of the engines, prevailed on board the aircraft. The flight attendants were clearing away the last of the lunch trays into their trolleys, some of the 303 passengers were waiting near the toilets, and others were passing the time with stretching exercises.

Ben Cave unfastened his seatbelt, stood up, opened the overhead luggage compartment and fished around for a magazine and a pen, hoping to make the remainder of the flight pass more quickly.

That was when the longest few minutes of his life began.