How human error turned Air France's minor technical problem into tragedy

How human error turned Air France's minor technical problem into tragedy

PAUL KORING
WASHINGTON — The Globe and Mail
Jul. 05 2012
The grim reality emerging from the Air France Flight 447 disaster is that the Airbus A330 jetting from Rio to Paris slammed into the dark sea – killing all 228 passengers and crew – after pilot-induced loss of control when there was nothing significantly wrong with the plane.

The disaster was unprecedented. Never before has a modern airliner been wrenched by its pilots into such position that it – literally – stopped flying, leaving its doomed passengers in a freefall to their deaths while the confounded flight crew debated what they had done and needed to do.
There was no terrorist bomb, nor a lightning strike that destroyed the plane’s electronics, although wild media speculation suggested the latter two in the early days after Air France 447 mysteriously
disappeared without a trace.

The flight controls all worked, the engines were delivering full power and the instruments were accurately telling the pilots that the aircraft was pointed nose-high at an angle three times what is normal at takeoff and falling at nearly 200 kilometres an hour straight down, wings level.

When everything else is stripped away, three highly paid, supposedly highly trained pilots, flying a modern, well-maintained aircraft for a major Western carrier on a routine transatlantic night flight completely overreacted to a minor instrument failure, and then for a nightmarishly long three minutes thirty seconds failed to cope with the upset they had created.

“The crew never grasped that they had stalled,” Alain Bouillard, the lead investigator for France’s Bureau d’Enquêtes et d’Analyses, said at Thursday’s briefing before the long-awaited release of the probe’s final report. “They failed to understand the stall and they failed to recover from it.”

To be sure, it was a dark and stormy night. Heavy turbulence and a line of massive thunderstorms lay across the plane’s path. Ice crystals coated the thin Pitot tubes protruding from the Airbus that measure air speed. When they iced up, the speed data to the flight computers became unreliable. That triggered the autopilot to disconnect, putting the plane back into the hands of the pilots to fly manually.

It wasn’t a new or especially tough problem. Investigators uncovered at least 36 other similar instances that triggered the autopilot to disconnect, although the Air France crew probably hadn’t heard of them on the fateful flight. In none of the other cases had pilots lost control and crashed.

But on June 1, 2009, the Air France pilots turned the aviation equivalent of an automobile driver losing cruise control and then steering the car over a cliff. Flight 447 is the worst disaster ever for Air France and the first loss ever of a modern airliner from oceanic cruise that wasn’t caused by terrorist bomb or suicidal pilots.

There’s an old, grim flying truism, dating back nearly to the Wright brothers: “Pull back to go up, pull further back to go down.”

What is means is that gently pulling back on the stick (either a game-controller-like sidestick that Airbus uses or the bigger between-the-legs control yoke favoured by Boeing) lifts the nose and the plane, as long as the engines’ thrust is sufficient to keep climbing, goes up. But pull back too far, get the nose too high and the aircraft ceases to fly.

Seconds before the final impact, one of the pilots, still befuddled, says: “Damn, we’re going to crash, this can’t be happening.”

A debate rages among pilots – and has apparently been played out on airline simulators – as to how late into the Flight 447 accident sequence the pilots could have engineered a recovery. In the final official report, French investigators make clear that early corrective actions – pushing the nose down, building back flying speed in a dive and then resuming normal flight – would have worked.

But the window to save the aircraft was small. “Only an extremely purposeful crew with good comprehension of the situation could have carried out a manoeuvre that would have made it possible to perhaps recover control of the airplane,” they concluded. Instead, “the crew had almost completely lost control of the airplane.”

For the last 10,000 metres of freefall, the last two minutes, only test pilots might have pulled off the sort of dramatic, aggressive effort needed to save the plane. That might have involved throttling back one engine to force a wing drop, to drag the nose out of its 40-degree up angle into a dive.

Unprecedented as the Air France Flight 447 disaster may be, the investigation made scores of recommendations to avoid a repeat.

No one can mandate whether pilots will do the right – or wrong – things in a crisis, even a self-inflicting one. But better training, a better understanding of the different and more difficult flight handling in the thin air of high altitude, clearer warnings and better crew communication all might have broken the accident chain and averted disaster.

In hindsight, plenty went wrong. The senior captain, who was on mandated rest break, failed to properly brief the more junior pilots. The most junior of the three was flying, but his colleague, who had more experience, seemed more aware of the crisis yet never really took over. Nor did the captain on his return to an alarm-filled cockpit.

Air France defends its pilots and training, praising their doggedness. “The captain and two co-pilots remained fully engaged in flying the plane until the last moments,” the airline said.

For the passengers, an awareness of what was happening from the pilots at the front, would have been more useful.

A judicial inquiry into whether manslaughter charges can be laid and a myriad of civil suits filed is still pending.