Just as unexpectedly as it had taken control of the aircraft, the computer relinquished that control and the nose of the A330 suddenly returned to normal. The passengers were thrown back into their seats or onto the floor at one-and-a-half times the force of gravity.
"There was utter chaos around me," says Cave. Only three minutes later, the plane went into another eerie, uncontrollable nosedive. At 12:49 p.m., the aircraft transmitted an emergency "Mayday" message, followed by a second one five minutes later.
"The pilots are real heroes," Cave said ecstatically after an emergency landing at a tiny military base on the west coast of Australia.
But if the pilots are heroes, they are tragic heroes at best.
Instead of being able to pilot the plane, they were briefly transformed into helpless spectators. And it wouldn't have been long before they too became the victims of a plane gone amok, no longer stoppable by human intervention. If the nosedive had lasted a little longer, the plane might have reached a speed at which the pilots could no longer stop it without it breaking apart. The difference between life and death was a matter of seconds.
The incident on board Flight QF 72 resulted in 115 injuries, 12 of them serious, as well as two spinal injuries. The cabin ceiling was severely damaged in many places. "The oxygen mask was hanging down from the spot where I hit the ceiling," says Cave.
His wounds have long since healed, but the incident has left its mark on the pilots. There are 621 A330s in operation today, and one of them suddenly embarked on a bizarre life of its own.
What exactly happened on the circuit boards of aircraft computer system remains unclear. Defective readings apparently confused the flight computers, leading them to believe that the passenger jet was climbing steeply instead of cruising along a stable, horizontal path. This prompted the computers to push the nose down, without any pilot input, to protect the aircraft from the perceived danger of sideslipping. "We want to know, as quickly as possible, how exactly this could have happened," says a Lufthansa pilot who flies the same Airbus long-haul aircraft.
Julian Walsh, of the Australian Transport Safety Bureau (ATSB), openly articulates what the manufacturer and the airline would prefer to keep quiet about Qantas Flight 72: "Certainly there was a period of time where the aircraft performed on its own accord."
This arouses our primal fear of technology acting independently and assuming power. Just as HAL, the on-board computer in Stanley Kubrick's sci-fi classic "2001: A Space Odyssey," assumes control of the spaceship, the Qantas computers made arbitrary decisions.
The crash of another Airbus A330 on June 1, 2009, raises similar concerns. Air France flight AF 447 was at cruising altitude en route from Rio de Janeiro to Paris when it suddenly plunged into the Atlantic Ocean and killed all 228 people on board. It is possible that the real cause of the crash will never be known.
In that accident, the final signals that were transmitted by the doomed aircraft's computers via satellite also provide evidence of digital problems on board. Twenty-four matter-of-fact maintenance messages to headquarters in Paris indicate that the speed sensors reported defective data, and that the flight computers switched themselves off because they were incapable of processing the contradictory data.