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

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Part 4: Minute Three: Freefall


Not long after the airspeed indicator failed, the plane went out of control and stalled. Presumably the airflow over the wings failed to provide lift. Arnoux, from the pilots' union, estimates that the plane fell toward the sea at about 42 meters per second (95 mph) -- almost the same speed as a freefalling parachutist.

Arnoux's version of events is based in part on the timing of a transmitted error message about the equalization of pressure between the cabin and the outside of the plane, which usually happens at 2,000 meters (7,000 feet) above sea level. Had the airplane nosedived, this alarm would have been triggered earlier. "It takes almost exactly four minutes to freefall from cruising altitude to sea level," Arnoux says.

Photo Gallery

4  Photos
Photo Gallery: The Final Minutes of Flight 447

According to this scenario, the pilots would have been forced to watch helplessly as their plane lost its lift. That theory is supported by the fact that the airplane remained intact to the very end. Given all the turbulence, it is therefore possible that the passengers remained oblivious to what was happening. After all, the oxygen masks that have been recovered had not dropped down from the ceiling because of a loss of pressure. What's more, the stewardesses weren't sitting on their emergency seats, and the lifejackets remained untouched. "There is no evidence whatsoever that the passengers in the cabin had been prepared for an emergency landing," says BEA boss Jean-Paul Troadec.

Two seemingly insignificant lines from the warning reports transmitted by the aircraft show how desperately the pilots fought to keep control. They read "F/CTL PRIM 1 FAULT" and "F/CTL SEC 1 FAULT".

This somewhat cryptic shorthand suggest the pilots tried desperately to restart the flight computer. "It's like trying to turn your car engine off and then on again while driving along the motorway at night at 180 kilometers an hour (110mph)," says Arnoux.

The attempt to resuscitate the on-board computer proved unsuccessful. For the last 600 meters (2,000 feet) before impact, the pilots' efforts would have been accompanied by the chilling calls of an automated male voice: "Terrain! Terrain! Pull up! Pull up!"

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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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