There was plenty of backlash when I wrote about the causes of the 2009 crash of Air France flight 447 into the Atlantic Ocean back in May. Many of you wanted to wait until the final report came out, but I was confident that the story had become quite clear. With the latest interim report (which I can only find in French – summary in English is here), it looks like I was right on track.
Here’s what I said at the end of my last post:
Remember, the pilots were already working to pick their way through the worst of the storms. Add to that the loss of the autopilot, dozens of failure messages, and inconsistent speed readings and it seems like the answer might be simple. The pilots may have been so distracted that they forgot to do the one thing they needed to do to survive: fly the airplane. Once the final report is issued, look for training changes to come out of this and possibly even some changes in the way Airbus puts its airplane logic together.
Sure enough, the focus of the latest report is on training and puts a lot of the blame on Air France, but there is some discussion about aircraft logic as well. This has been enough for the investigators to push out safety recommendations, though not without controversy.
Throughout this 3rd interim report, a picture of normalcy is painted throughout the beginning of the flight. It was noted that when the Captain left to take his rest, he didn’t leave “clear operational instructions” and there was “no explicit task-sharing” between the two remaining pilots, but the crew composition was fine and the aircraft weight and balance was within the proper limits.
As mentioned in the last report, the crew was well aware of the weather ahead and had made course corrections to avoid the worst of it. That’s when things got ugly.
According to the report, the aircraft was flying at the “upper limit of a slightly turbulent cloud layer” when the autopilot disconnected. It’s believed that this happened because the pitot tubes froze over and that gave the aircraft incorrect speed information. When the system can’t make sense of the information it’s being fed, it shuts off autopilot and the pilots have to fly the airplane. Turbulence, however, was not a problem. The plane was perfectly flyable, but poor decision-making fed by weak training brought the airplane down.
Proper procedures were not followed for dealing with unreliable airspeed indication. To make things worse, neither of the two copilots had been trained to properly handle manual flying at high altitude. Despite the stall warning, the pilots continued to apply nose-up pressure, the opposite of what they should have done. In less than a minute, the plane went from being correctable to operating outside the design limits because of the improper recovery efforts by the pilots.
About 1 minute and 30 seconds after the autopilot disconnected, the Captain came back into the cockpit. At this point, stall warnings were going on and off and the airplane was still at 35,000 feet. Unfortunately, it was also losing 10,000 feet per minute as forward speed just disappeared. At times, the aircraft rolled from side to side as the pilots struggled to get the airplane under control. Those in the back must have felt sheer terror. The pilots never made an announcement to the passengers, and soon after, they all plunged into the Atlantic. I get goose bumps just thinking about how awful that must have been.
So after all that, what have we learned? We know the aircraft functioned properly. Were it not for the pitot tubes freezing over, this would have been a routine flight. Even when the pitot tubes failed, had the pilots been able to properly fly the aircraft manually, the passengers probably wouldn’t have even known there was an issue. Out of this, the French accident investigators have released safety recommendations that will need to be implemented by regulators in order to go into effect.
The main recommendation is around training. The idea is to make sure that all pilots have the proper training for manual flight at high altitudes, a skill which is rarely used in commercial aviation today. There is also additional training suggested around stall avoidance and recovery. Additionally, it’s suggested that the role of relief captain should be better-defined when the Captain is on rest. This way, there will be less confusion and more defined task-sharing if something goes wrong.
But the blame wasn’t solely on the training and pilots. One recommendation for aircraft manufacturers is to look at including an angle of attack indicator that pilots can see on the flight deck. There is an indicator showing the angle of the aircraft to the ground, but there isn’t one that shows the angle of the wing as compared to the direction of the air (angle of attack). That could have helped the pilots in their recovery efforts.
One recommendation not made was to revisit the way stall warnings are handled on the A330 aircraft. In fact, the pilots union at Air France is so angry about this being left out that it has decided to stop cooperating with the investigation. The on-and-off nature of the stall warning may have simply added to the confusion, and made it more difficult for the pilots to make the right moves. The investigators say that there wasn’t enough evidence to include this just yet, but it will be discussed in some form in the final report.
Regardless of what comes out in the final report, the picture is already very clear. It seems that current pilot training standards were not enough to help these pilots get out of an entirely recoverable situation. Were the Brazilians running this investigation, they probably would have already filed criminal charges against anyone they could, but the French handle this properly. Find the problem, fix the holes, and make sure that something like this never happens again.
[Photo of Sister Ship to Crashed Airplane via Flickr user Tab59|CC 2.0]
