July 20, 2012
The Verdict on Air France 447
Over the past couple of weeks I’ve had the chance to talk with other pilots about the tragic Air France accident that occurred on June 1, 2009. These discussions were prompted by the recent release of the final accident report and the transcript of conservations in the cockpit.
In the initial aftermath of the crash, there was a lot of speculation that the plane had broken up in flight after encountering a severe thunderstorm over the Atlantic Ocean. The in-flight break-up, so the conventional wisdom went, resulted from the pitot-static system icing up, thereby giving erroneous information to the pilots who inadvertently over-stressed the airframe.
It was nearly two years later, in April 2011, that the main debris field was located. The pattern of debris suggested that the plane had been intact upon impact with the ocean. Incredibly, the Flight Data Recorder (FDR) was located, followed by the discovery of the Cockpit Voice Recorder (CVR) a week later. With the information provided by these “black boxes,” the story of what happened becomes much clearer.
The Air France 447 Cockpit Voice Recorder, found on the ocean floor (Photo: BEA)
A few things about this accident jump out at me when I read the transcript. There never seems to be any clear understanding between the two First Officers as to who is actually flying the plane. The more junior FO is the designated “flying pilot” at this point, while the Captain is on his rest break, but the other, more senior, FO makes control inputs at some points. Basic crew resource management requires that one pilot be flying at any given time and that the division of duties is always made clear (e.g. “You have the airplane”, “I have the airplane”).
Here’s the part that I believe was a major contributor to the accident. On the Airbus, when one pilot makes a control input (e.g. pulling back on the sidestick), the other pilot has no indication of this control movement. Compare this to more traditional aircraft, which have control yokes in front of both pilots. On these planes, when one pilot moves the yoke, the other pilot’s yoke moves in tandem. If I hold full back stick, this is glaringly obvious to the other pilot. Apparently this is not so on an Airbus. In addition, when both pilots move their respective control sticks, the inputs are averaged. So, when the senior FO made an attempt to lower the nose of the plane, his efforts were stymied by the junior FO who was holding back stick throughout the descent.
Though all of these things were major contributors to this accident, the root problem seems to be a lack of basic airmanship. The initial response by the junior FO to the loss of airspeed information (initiating a climb) was not something an experienced pilot should ever do, particularly when already at a safe altitude. But this initial mistake was still very recoverable. All that was needed was to lower the nose to regain airspeed and fly out of trouble. Instead, he compounded the problem by continuing to hold back pressure throughout the descent, causing a perfectly good plane to stall all the way to impact.
Like every other pilot, I’d like to think that I wouldn’t have made these mistakes. But I wasn’t there, so I don’t know how the confusion of the situation would have affected me, and I hate being the Monday-morning quarterback. I am glad that the black boxes were recovered so we don’t have to wonder about some mysterious gremlin that might pop up unexpectedly on some other flight. Somehow, it’s reassuring to me to know that the cause was more mundane, and eminently avoidable.
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I’m surprised in this age of electronic flight controls that there is not already in wide use by Airbus some sort of alert system be it audible, visual or physical (think stick shaker) or even some combination of these to inform the crew when counter inputs are occurring. Seems like it would be a simple & inexpensive fleet-wide preventative when compared to the cost in lives & lost equipment for a single incident. Considering this development, I can only imagine that this information has added fuel to the legal fires in any lawsuits against Airbus & Air France regarding this crash.
Comment by Mike Burkholder — July 21, 2012 @ 6:03 pm
Ive been thinking about this accident also. Complete pitot static failure, i guess there are no other alerting mechanisms besides those taught in basic ground school? I know during most of my commercial flying my eyes are never far from my gps ground speed reading, id love to think I could deduce I wasn’t stalling just based on that gps speed. Direct linkages allow a pilot to feel control pressure warnings during slow flight and stall/ buffet, I guess airbus might be lacking such a feedback? I hope the conditions leading to the accident are now a regular part of sim training. Lorne
Comment by Lorne — July 22, 2012 @ 8:25 pm
Lorne, please don’t make the mistake of thinking that your ground speed is any indicator of whether or not you are stalling. In a C-152, you could be cruising at 100 kts into a 40 knot headwind and showing 60 kts over the ground. No need for concern; it’s only the airspeed that matters. (Conversely, you could be on the ragged edge of stall with a 40 knot tailwind and think everything is just fine based on your ground speed.)
Comment by Steve Satre — July 22, 2012 @ 11:58 pm
Yes I understand but usually one has already absorbed that info (headwind or tailwind) when flying a prolonged heading, I am more meaning it could be a means of noting dramatic changes in airspeed. If this crew were in a prolonged stall even with a 50kt tail wind the ground speed would have shown an unusually slower speed.
Comment by Lorne — July 23, 2012 @ 5:57 am
I cannot conceive of a dumber design error than permitting the two sets of controls to cancel each other out. Only one pilot should be in control at any given moment. Airbus’ version of “fly-by-wire” goes much too far to relinquish control of the airplane, and simply flying resonsibility and control over to computers which do the actual flying. Fly-by-wire works great in a single-seat fighter; but it’s lousy when there are two pilots competing for control.
Comment by Rick Friedling — July 23, 2012 @ 8:22 pm
Hi Steve, with respect to your comments on both sidesticks being averaged….I understood that sidestick inputs were added not averaged…I stand to be corrected though.
Comment by G Kane — July 26, 2012 @ 7:19 pm
Yes, that makes more sense. If the inputs were averaged, there would be no way to achieve full fore or aft stick under normal circumstances (since the non-flying pilot’s control is neutral, i.e. a “zero” input). Thanks for catching this.
Comment by Steve Satre — July 27, 2012 @ 4:30 am
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.
Comment by Nalliah Thayabharan — August 2, 2012 @ 12:59 am