Last minutes of flight AF447
December 7, 2011 6 Comments
A transcript of the cockpit voice recorder in the final minutes of flight Air France 477 was leaked in the book Erreurs de Pilotage, and in turn a good article was created here. I’ve excerpted a few bits of dialogue below, but plenty more in the full version.
02:08:07 (Robert) Tu peux éventuellement prendre un peu à gauche. On est d’accord qu’on est en manuel, hein?
You can eventually pull it a little to the left. We’re agreed that we’re in manual, yeah?
02:10:06 (Bonin) J’ai les commandes.
I have the controls.
02:10:07 (Robert) D’accord.
Okay.
Bonin reacts irrationally. He pulls back on the side stick to put the airplane into a steep climb, despite having recently discussed the fact that the plane could not safely ascend. The stall warning sounds, a synthesized human voice that repeatedly calls out, “Stall!”, followed by a loud and intentionally annoying sound called a “cricket.” For the duration of the flight, none of the pilots will mention it, or acknowledge the possibility that the plane has indeed stalled—even though the word “Stall!” will blare through the cockpit 75 times. Throughout, Bonin will keep pulling back on the stick, the exact opposite of what he must do to recover from the stall.
02:11:21 (Robert) On a pourtant les moteurs! Qu’est-ce qui se passe bordel? Je ne comprends pas ce que se passe.
We still have the engines! What the hell is happening? I don’t understand what’s happening.
“If the person in the right seat is pulling back on the joystick, the person in the left seat doesn’t feel it,” says Dr. David Esser, a professor of aeronautical science at Embry-Riddle Aeronautical University. “Their stick doesn’t move just because the other one does, unlike the old-fashioned mechanical systems like you find in small planes, where if you turn one, the [other] one turns the same way.” Robert has no idea that, despite their conversation about descending, Bonin has continued to pull back on the side stick.
02:13:40 (Robert) Remonte… remonte… remonte… remonte…
Climb… climb… climb… climb…
02:13:40 (Bonin) Mais je suis à fond à cabrer depuis tout à l’heure!
But I’ve had the stick back the whole time!
At last, Bonin tells the others the crucial fact
02:13:42 (Captain) Non, non, non… Ne remonte pas… non, non.
No, no, no… Don’t climb… no, no.
02:13:43 (Robert) Alors descends… Alors, donne-moi les commandes… À moi les commandes!
Descend, then… Give me the controls… Give me the controls!
Bonin yields the controls, and Robert finally puts the nose down. The plane begins to regain speed. But it is still descending at a precipitous angle. As they near 2000 feet, the aircraft’s sensors detect the fast-approaching surface and trigger a new alarm. There is no time left to build up speed by pushing the plane’s nose forward into a dive. At any rate, without warning his colleagues, Bonin once again takes back the controls and pulls his side stick all the way back.
02:14:23 (Robert) Putain, on va taper… C’est pas vrai!
Damn it, we’re going to crash… This can’t be happening!
Why did the pilot ignore the stall warning?
According to the article,
the reason may be that they believe it is impossible for them to stall the airplane. It’s not an entirely unreasonable idea: The Airbus is a fly-by-wire plane; the control inputs are not fed directly to the control surfaces, but to a computer, which then in turn commands actuators that move the ailerons, rudder, elevator, and flaps. The vast majority of the time, the computer operates within what’s known as normal law, which means that the computer will not enact any control movements that would cause the plane to leave its flight envelope.
But once the computer lost its airspeed data, it disconnected the autopilot and switched from normal law to “alternate law,” a regime with far fewer restrictions on what a pilot can do. “Once you’re in alternate law, you can stall the airplane,” Camilleri says.
According to Camilleri, not one of US Airway’s 17 Airbus 330s has ever been in alternate law. Therefore, Bonin may have assumed that the stall warning was spurious because he didn’t realize that the plane could remove its own restrictions against stalling and, indeed, had done so.
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Marc Gawley 
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The BEA report is a whitewash of the fact that the junior co-pilot flying panicked on hearing the stall horn and pulled the joystick fully back until it crashed at terminal velocity (124 mph), thinking he was in a low-altitude take-off and go-around. The crew had never been trained to handle high-altitude stalls; the fatal stall was pilot-induced!
Unlike other flights that night, these Bozos hadn’t re-routed to avoid the storms and the weather radar had been set on the wrong range until it was too late. Captain’s fault. The captain then goes for a nap without designating command or replying to the junior pilot’s question about the inter-tropical convergence zone. Only the co-pilot not flying notices the weather radar discrepancy later and advises junior ‘Go left a bit’.
Stinginess by Air France meant this plane’s pitot air-speed tubes had not been upgraded, so all 3 iced-up in the storm, causing dis-engagement of the autopilot. Junior pulls the plane up to its ceiling of 38,000 feet, then it plummets like a stone with its nose up in the rarified air.
Chaos reigned: turbulence, popping ears, loss of data screens, warning horns. The pitot tubes came back online quite quickly, so they could have re-engaged the autopilot but the junior co-pilot flying was pulling the nose up for all he was worth. If he had only released the joystick the situation would have ameliorated, even stabilised, while they still had altitude.
Captain eventually returns but doesn’t take the controls, or even notice that junior is pulling the joystick back like a maniac as the stall warning horn sounds 75 times. Crew discuss whether they are rising or falling while the fully-functional altimeter in front of them is spinning down at a rate of knots.
Senior co-pilot in left seat fails to press over-ride button to disable junior’s joystick; at times they are both making inputs, and the A330 accepts dual control — oops — serious design fault there!
Under control of The Three Stooges, a crash is inevitable. Lessons have been learned but Boeing’s dual-yoke system would have saved the day. Airbus is unlikely to relinquish its video-game joysticks as blame ricochets between the planemaker and Air France.
The accident was caused by the co-pilot induced stalled glide condition and remained in that condition until impact. To recover from stall is to set engine to idle to reduce nose up side effect and try full nose down input. If no success roll the aircraft to above 60° bank angle and rudder input to lower the nose in a steep engaged turn. Pilots lack of familiarity and training along with system malfunction contributed to this terrible accident. Also the following contributed to the accident
(1)the absence of proper immediate actions to correct the stalled glide
(2) Insufficient and inappropriate situation awareness disabling the co-pilots and the captain to become aware of what was happening regarding the performance and behaviour of the aircraft
(3)lack of effective communication between the co-pilots and the captain which limited the decision making processes, the ability to choose appropriate alternatives and establish priorities in the actions to counter the stalled glide
During most of its long descent into the Atlantic Ocean, Airbus A330-203 was in a stalled glide. Far from a deep stall, this seems to have been a conventional stall in which the Airbus A330-203 displayed exemplary behavior. The aircraft responded to roll inputs, maintained the commanded pitch attitude, and neither departed nor spun. The only thing the Airbus A330-203 failed to do well was to make clear to its cockpit crew what was going on.Its pitch attitude was about 15 degrees nose up and its flight path was around 25 degrees downward, giving an angle of attack of 35 degrees or more. Its vertical speed was about 100 knots, and its true airspeed was about 250 knots. It remained in this unusual attitude not because it could not recover, but because the co-pilots did not comprehend in darkness, the actual attitude of the aircraft. The co-pilots held the nose up. If the co-pilots had pushed the stick forward, held it there, and manually retrimmed the stabilizer, the airplane would have recovered from the stall and flown normally.
Air France complained that the copilots did not have enough time to analyze the situation. Gravitational stalled glide does not allow timeouts, to thoroughly discuss the situation to find out what went wrong. The co-pilots – 37 year old David Robert and 32 year old Pierre-Cédric Bonin missed the cardinal rule that first they must fly the airplane, and after start analyzing the situation, since a falling airplane is not going to wait for them. If they did not understand the instruments, then instead of pondering on it they should have come to the quick conclusion that they did not understand those instruments, and apply the unreliable airspeed procedure clearly prescribed for that situation, which is a blind, given thrust and pitch setting for the given configuration, and let the airplane fly itself, and only after get to analyzing what went wrong, and by the time they finished, the root-cause (pitot icing) would have probably cured itself. It was the safe solution to the problem, but not applied.
The Airbus A330 performed exactly as it was designed and described when the stall warning cut out at the end of valid values, except the co-pilots did not know it. Unfortunately, it happens too often with catastrophic results that pilots are not familiar with the systems of their own airplane, such as in the case of American Airlines 587 over Queens, which was clearly the airline’s fault.
Air France also argued that the stall warning system in the A330 is too “confusing”. Every modern airplane is quite a confusing piece of machinery. It is full of buttons, levers, all kinds of red, yellow, green lights with buzzers, and a host of other indicators and controls inside, which can look very confusing indeed, but it is the pilot’s duty to reign on them, or not to be pilot.
Airbus A330-203 is a new generation, highly automated piece of equipment with drastically simplified controls, displays, and instrumentation compared to older models. Still, pilots with the same human capabilities as the ones on Air France flight 447 could very well stay in full control in those planes, and many times acted heroically saving situations much graver than where the plight of Air France flight 447 started, such as United Airlines flight UA232 at Sioux City, or Air Canada flight AC143, the Gimli Glider. If those pilots could perform well in those older, much more complicated aircraft in tougher situations, then there is no excuse for the co-pilots of AF flight 447 to be confused in a generally much simpler and easier-to-fly aircraft.
The Airbus A320 is a digital fly-by-wire aircraft as the flight control surfaces are moved by electrical and hydraulic actuators controlled by a digital computer. The computer interprets pilot commands via input from a side-stick, making adjustments on its own to keep the plane stable and on course, which is particularly useful after engine failure by allowing the pilots to concentrate on engine restart and landing planning. Some say the Airbus A330 is a “video-game” airplane due to its side-stick control, which does not match up in real hard situations. But who can say that after the successful ditching of US Airways flight 1549 on the Hudson River? It was an Airbus A320 with the same side-stick control, and it matched up with the hardest situation very well with an experienced 57 year old Captain Chesley Sullenberger at the command. The Airbus A330 is not a video-game airplane, it is the airlines that make it a video-game by cutting corners, taking advantage of its superior automated capabilities thinking that it flies by itself, and no training and no knowledge of even the basics of the principles of flying is required in them for their pilots, as was demonstrated by the co-pilots of flight 447, who seemed to be incapable to react even on a basic level to the phenomenon of the aerodynamic stall. The co-pilots had not applied the unreliable airspeed procedure. The co-pilots apparently did not notice that the plane had reached its maximum permissible altitude. The co-pilots did not read out the available data like vertical velocity, altitude, etc. The stall warning sounded continuously for 54 seconds. The absence of any training, at high altitude, in manual airplane handling and in the procedure for ”Vol avec IAS douteuse” (Flight with questionable Indicated Airspeed) caused this terrible accident. Evidently, it might not be what Airbus had on its mind designing the aircraft. They might have meant the best of the both, an airplane with superior controls, matched with seasoned pilots with superior education in the principles of flying and the handling of hard situations, best of the best, as airlines are prone to boast of their flying personnel, to represent quality improvement in flying safety by this pairing. Now, if this piece of equipment falls in the hands of the airlines who use it as a video game to save training costs, telling only their pilots that “if the red light on the right side blinks, just pull the stick back as hard as you can, and let the system do the rest”, they can get away with it as long as everything is normal, the airplane is good enough for that, but in unforeseeable situations, such as the flight 447 en-route to Paris on that night, without any independent knowledge of flying in general, the video-gaming with the aircraft may ultimately come to a fatal end.
However, beyond the reasoning and explanations there is still some eeriness about the crash, taking in consideration that Air France flight 447’s pilots just sat there in daze squeezing the control stick, barely being able to do more than commenting on how the airplane was falling out of the sky until crashing into the Atlantic Ocean, the arrival of the 58-year-old flight captain Marc Dubois in the cockpit not making much a difference either. The question might arise whether weren’t the pilots in a mentally incapacitating state of shock and disbelief? Whether do or can Air France test pilots of how well they can keep their mental stability under the duress of a catastrophic situation? None of it seems to be the fault of the Airbus A330, which needs only good, trained pilots to give superior performance for the good of the flying public. Very similarly 3 decades ago Captain Madan Kukar’s mistaken perception of the Air India Flight 855 situation resulted in causing the Boeing 747-237 to rapidly lose altitude and the airplane hit the Arabian Sea at 35 degree nose-down angle.
Practicing recovery from “Loss of Control” situations and improve flight crew training for high altitude stalls (simulator training usually has low altitude stalls which are significantly different due to energy status of the aircraft) should become the mandatory part of recurrent training.
AF447 crashed because the pilot flying held the side-stick fully back WITHOUT informing the other 2 pilots until it was too late to pull up.
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