ATSB concludes investigation into unreliable airspeed indication incident involving an Airbus A330

Location of pitot and TAT probes on an A330 (Photo: ATSB)

The Australian Transport Safety Bureau (ATSB) concluded their investigation into an unreliable airspeed indication incident involving an Airbus A330.

On 28 October 2009, an Airbus A330-202 aircraft, registered VH-EBA, was being operated as Jetstar flight 12 on a scheduled passenger service from Narita, Japan to Coolangatta, Australia. Soon after entering cloud at 39,000 ft, there was a brief period of disagreement between the aircraft’s three sources of airspeed information. The autopilot, autothrust and flight directors disconnected, a NAV ADR DISAGREE caution message occurred, and the flight control system reverted to alternate law, which meant that some flight envelope protections were no longer available. There was no effect on the aircraft’s flight path, and the flight crew followed the operator’s documented procedures. The airspeed disagreement was due to a temporary obstruction of the captain’s and standby pitot probes, probably due to ice crystals. A similar event occurred on the same aircraft on 15 March 2009.

The rate of unreliable airspeed events involving the make of pitot probes fitted to VH-EBA (Goodrich 0851HL) was substantially lower than for other probes previously approved for fitment to A330/A340 aircraft.

In it’s investigation into the June 1, 2009 accident involving an Air France A330 (flight AF447),  the French Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile (BEA) found 36 occurrences between the period 12 November 2003 and 7 August 2009 that the aircraft manufacturer concluded were attributable to the blocking of at least two pitot probes by ice.  27 events involved aircraft fitted with Thales model C16195AA pitot probes, the same model fitted on the AF447. Two events involved aircraft fitted with Goodrich 0851HL probes.

Both of the events involving VH-EBA occurred in environmental conditions outside those specified in the certification requirements for the pitot probes. The French Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile (BEA) has recommended the European Aviation Safety Agency (EASA) to review the certification criteria for pitot probes in icing environments.

At the time of the occurrence, most of the operator’s A330 pilots had not received unreliable airspeed training. Most of these pilots had transferred from the operator’s A320 fleet, and the third-party training provider had not included the topic in its A320 endorsement training program, even though it was included in the aircraft manufacturer’s recommended program since 2004.

The operator identified the problem and included unreliable airspeed in its recurrent training program for the A320 from May 2009 and the A330 from October 2009. The training provider included the topic in its endorsement program from July 2010. The operator, training provider and the Civil Aviation Safety Authority all initiated safety action to minimise the likelihood of similar problems in the future.

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2 Responses to ATSB concludes investigation into unreliable airspeed indication incident involving an Airbus A330

  1. The problem could be deeper. It is not a matter of reliability of speed information (as serious as it could be). It is a matter of the behaviour of automatic systems acting over the wrong information.

  2. Nandor Vestroci says:

    Air France vs. Airbus; the video-game aircraft.

    Air France (not unexpectedly) partially shifting the blame on Airbus for the crash of flight 447. They complain that the pilots did not have enough time to analyze the situation. But whose fault is it that gravity does not allow timeouts, so a round table could be called together to thoroughly discuss the situation to find out what went wrong, Airbus’s? Air France acts as if they would think so. They cannot deny that the pilots missed the cardinal rule in this situation, 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.
    Air France and its pilots are blaming the stall warning system, which shuts off when the readings become invalid. First, somebody should challenge Air France’s chief pilot, who is absolutely defending the actions of their pilots as being “professional”, exactly what he would do in the same situation, the same as they did? Safe to assume, he would not dare say so. Since then Air France changed the Thales pitots (which were already slated for change), its training, including cockpit resource management, as a tacit acknowledgement of its own fault. Further, the aircraft performed exactly as it was designed and described when the stall warning cut out at the end of valid values (extreme stall), except the 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 Qeens, which is clearly the airline’s fault. Of course, afterwards it is easy to make various arguments of how the situation could have been saved by others, but in case pilots do not or cannot fly by the book, the blame is solely theirs. Air France also argues that the stall warning system in the A330 is too “confusing”. Well, it must be realized, that an 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 miracles inside, which can look very confusing indeed, but it is the pilot’s duty to reign on them, or not to be pilot. You simply cannot be a pilot if you are only familiar with the fun part.
    With respect to the big confusion, the question is, was this stall warning device the straw that broke the back of the camel? In other words, if the pilots would not have had to remember just this one thing that the stall warning stops in extreme situations, then confusion would not have set in, and they could have perfectly saved the situation? Well, the A330 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 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 447 started, such as UA flight 232 at Sioux City, or Air Canada 143, the Gimli Glider. If those pilots could perform well in those older, much more complicated aircraft in thougher situations, then there is no excuse for the pilots of 447 to be confused in a generally much simpler and easier-to-fly aircraft.
    Some say the A330 is a “video-game” aircraft because of its side-stick control, which does not match up in real hard situations. But who can say that after the brilliant ditching of US Airways 1549 on the Hudson River? It was an A320 with the same side-stick control, and it matched up with the hardest situation very well, of course, with a seasoned pilot at the controls. The A330 is not a video-game aircraft, 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 pilots of flight 447, who seemed to be incapable to react even on a basic level to the phenomenon of the aerodynamic stall. Evidently, it might not be what Airbus had on its mind designing the aircraft. They might have meant the best of the two, 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 one 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 reasonings and explanations there is still some eeriness about the crash, taking in consideration that Air France is certainly no third-world airline, and still three of their 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, the arrival of the captain in the cockpit not making much a difference either. The question might arise whether weren’t they in a mentally incapacitating state of shock and disbelief? Whether do (or can) airlines test their pilots of how well they can keep their mental stability under the duress of a catastrophic situation? Wasn’t it a twist of fate unknown to anyone that three pilots prone to loose their cool and judgement in life-threatening situations got together in one cockpit and got into this situation, as stipulated by Murphy’ law, a true scourge of aviation?
    None of it seems to be the fault of the airplane, which seems to need only matchingly good, trained pilots to give superior performance for the good of the flying public.

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