Death in the Atlantic The Last Four Minutes of Air France Flight 447

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Part 3: Minute Two: Loss of Control


Did the pilots on flight AF 447 know about the airspeed indicator failures experienced by colleagues on nine other aircraft belonging to their own airline? Air France had indeed distributed a note about this to all its pilots, albeit as part of several hundred pages of information that pilots find in their inbox every week. One thing is certain: The pilots on flight AF 447 had never trained in a flight simulator for a high-altitude breakdown of the airspeed indicator.

The situation in the cockpit was made even more difficult by the fact that the flight computer of the A330 put itself into a kind of emergency program. The plane's digital brain usually supervises all activity by its pilots -- at least, as long as its sensors provide reliable data. Without a speed reading, the computer more or -less throws in the towel, which doesn't make things easier for the pilots.

Photo Gallery

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Photo Gallery: The Final Minutes of Flight 447

"The controls suddenly feel completely different to the pilot," says flight expert Hüttig. The sheer complexity of the Airbus' systems makes it difficult to control in critical phases of the flight. It would be easier for pilots if they could simply switch the computer off in critical situations, as is possible on Boeing planes.

Pitot tubes sometimes also fail on Boeing aircraft. When SPIEGEL contacted the American Federal Aviation Administration, the body which oversees civilian flight in the US, the FAA confirmed that there had been eight such incidents on a Boeing 777, three on a 767, and one each on a 757 and a Jumbo. Boeing is currently conducting a study on the safety effects of "high-altitude pitot icing on all models in its product line," says FAA spokeswoman Alison Duquette. The FAA did not, however, identify "any safety issues arising" during these incidents.

Could it therefore be that the flight computer, which is hard to manage in emergencies, actually contributed to the loss of control by the Airbus pilots? Air-safety experts Hüttig and Arnoux are demanding an immediate investigation into how the Airbus system reacts to a failure of its airspeed sensors.

Unexpected Reaction

In early March, the BFU in Germany is due to publish the findings of its investigation into the near-crash of a Lufthansa A320 two years ago at Fuhlsbüttel Airport in Hamburg, a report that will undoubtedly prove uncomfortable reading for Airbus. In that incident, an unexpected reaction by the flight computer caused the jet's left wing to scrape along the runway while landing. The BFU is due to issue 12 safety recommendations, some of which concern Airbus' computer programs.

So far, it's unclear who was controlling the Air France plane in its final minutes. Was it the experienced flight captain, Dubois, or one of his two first officers? Typically, a captain retreats to his cabin to rest a while after takeoff. Indeed, there's corroborative evidence to suggest that the captain was not sitting in the cockpit at the time of the crash: His body was recovered from the Atlantic, whereas those of his two copilots sank to the bottom of the ocean still attached to their seats. This would suggest that Dubois was not wearing a seatbelt.

In contrast to many other airlines, it is standard practice at Air France for the less experienced of the two copilots to take the captain's seat when the latter is not there. The experienced copilot remains in his seat on the right-hand side of the cockpit. Under normal circumstances, that is not a problem, but in emergencies it can increase the likelihood of a crash.

As a consequence, it was probably the plane's third pilot, Pierre-Cédric Bonin, a dashing amateur yachtsman, who steered the aircraft to its doom. Bonin's wife was also on board, while their two children were at home with their grandfather.

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vluthra1 02/25/2010
1. AF 447 Crash Analysis
Is the European Aviation Safety Agency (EASA) a sitting duck, when it comes to minding or controlling its own kith-kin AB? If faulty equipment can jeopardize hundreds of lives, why are they not being summoned into the European Courts of Justice for negligence in allowing unsafe equipment to be declared safe? And then comes the question of Pilot competence. As we fly, we entrust our lives with the men/women who command these birds. But do they know all, that they need to know, to do their job right? Are they somewhat like the doctors, who can actually test and try in real life situations?
globetrodden 02/26/2010
2. Not True
"...'But pilots are very reluctant to do something like that,' Hüttig adds. After all, it makes the flight more expensive, causes delays and is frowned upon by airline bosses. ... " That's nonsense. The idea that pilots would fly through a dangerous storm to avoid delays or diversions is preposterous and, to an airline pilot like myself, highly offensive. Patrick Smith Boston
nikosathens 02/26/2010
3. air speed measurement
I'm a simple engineer and not an aircraft specialist and I wonder why a whole sophisticated airplane computer system can crash because of malfunction of the pitot tubes that measure the aircraft velocity. Could the pilot not cross-check the speed by a reading from a GPS system?
michaeljohnwright 02/27/2010
4. Michael Wright
I am a private pilot, and on one occasion had a similar incident, though in a small aircraft. It was not caused by the pitot tube getting iced up, but by the static pressure vent. This vent is also required to measure airspeed, but is also vital for altitude and vertical speed indications. When not working, the outside air pressure and altitude readings freeze, vertical speed is shown as zero, and the altimeter shows continuing increases in airspeed when descending. It would naturally lead to reducing air speed as the pilot tried to stop the increase in indicated air speed. This could lead to a stall in a few tens of seconds. It is perfectly possible to fly an aircraft without an air speed indicator, using a combination of vertical speed indication or altitude indication together with power setting.
oppen2 02/27/2010
5. Two points
An interesting and relatively thorough update on this crash, given the space available. An editor should have, though, caught two journalistic missteps: 1. "As a consequence, it was probably the plane's third pilot, Pierre-Cédric Bonin, a dashing amateur yachtsman, who steered the aircraft to its doom." Terribly unfair, with its implication that the senior pilot left the flight deck in the hands of an unqualified amateur. In his personal life, Bonin may have been dashing and enjoyed sailing. But he didn't arrive in the cockpit of a large jet with a major carrier without thousands of hours of experience and more stringent checks and rechecks of his ability than most of us will ever face in our professional lives. There is no evidence presented in the article that another pilot could have more successful in trying to recover control of the airplane. 2. "For several years now, Airbus has offered its customers a special safety program - called "Buss" -- at a cost of €300,000 per aircraft. If the airspeed indicator fails, this software shows pilots the angle at which they must point the plane. "Up to now, Air France has chosen not to invest in this optional extra for its fleet." Placement makes all the difference. Had these two paragraphs been in the main body of the story, they're relevant pieces of information. Placing them as the penultimate and then final paragraph is a journalistic trick to leave the reader with the somber conclusion that if only Air France had purchased this relatively inexpensive software, the accident would never have happened. Had the equipment been installed, many questions remain. The most obvious: Would it have functioned properly with the shutdown of the flight computer? The writer could have indicated how many other airlines purchase the optional software. And the obvious question not posed or answered: If the software is that important to the safe operation of the plane, why is it optional?
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