Tag Archives: Stall Training

New Ideas on AF 447 Stall Recognition & Stall Recovery Procedures

AF-447 Stall Recognition:

Were the Air France 447 Airbus 300-200 flight crew members trained in stall recognition by:

A) Angle of Attack (AoA) based stall warning alarm system or

B) Loss in altitude, as displayed on the altimeter, due to loss of lift?

C) Both A and B

D) Neither A nor B?


1. A stall of relative wind flow over the Airbus 330 wing occurred at Stall AoA, setting off the flight crew cockpit stall alarm system. The stall warning signaled that the AoA had increased above the Relative Wind Flow Stall AoA, and by aerodynamics, the wing was no longer producing enough lift for flight, and so the altimeter was unwinding rapidly, telling the flight crew that the aircraft was descending. But did the flight crew see the loss of altitude as a symptom of trouble, or the exacting cause of the trouble and their cue to enact stall recovery procedures? If they understood the loss of altitude as their cue that they were in a stall, why did they not immediately begin stall recovery procedures, such as lowering their nose attitude? I do not think that the other multiple alarms and warnings confounded the flight crew. I think that they did not see the unwinding altimeter as the stall recognition cue. If they did, they would have lowered the nose at 37,000 feet and resumed level flight. What was the confusion therefore, that confounded the AF 447 flight crew?

2. Is not the altimeter a very good and reliable indicator of a stall? Along with the AoA Stall Warning system, didn’t the flight crew have this very reliable and verifiable stall indicator, all the indication that they needed to solve their problem? Without a doubt, a rapidly decreasing altimeter is a very good stall indication, especially when the crew has nose up control inputs. Acting on that information alone, the crew would have been able to carry out published stall recovery procedures of lowing the nose to lower the AoA.

Altimeter in Stall Recognition


3. I would argue that, as the Air France Airbus descended from above 37,000 feet to the surface of the sea, loosing its altitude due to loss in lift,  the flight crew never recognized that the loss of altitude was their stall recognition cue. As a result, the crew never attempted standard operating procedure stall recovery by lowering the nose. Was the reason that the flight crew never realized that they were in a stall, due to the fact that they did not understand that the decreasing altitude as displayed on their altimeter, was the stall indication? Why was that the case for AF447? Is that still the case today at many commercial airlines around the globe?

4. From their stall recognition and stall recovery training at Air France Airbus training program, were the flight crew trained to recognize and recover from stall based only on the installed AoA-based stall warning system? Did AB and AF not require the altimeter as the next instrument to be checked for decreasing altitude, in the stall recognition and recovery procedure? How many other commercial pilots are their out flying the line, that do not understand stall recognition and stall recovery procedures?

5. Once a stall is recognized by observing the decreasing altitude on the altimeter, wouldn’t the next procedure in stall recovery be the same procedure of decreasing the nose attitude, just as in the case for stall recovery for AoA based stall warning? In the altimeter case, doesn’t the altimeter substitute for the AoA-based stall system for the stall recognition? Since the AF 447 flight crew never attempted stall recovery procedures, is it correct to conclude, that they never recognized that they were in a stall at all?

6. Should Air France, all airlines flying Airbus, and Airbus Training, and perhaps all commercial airlines, shift stall recognition and stall recovery procedures from focusing solely on AoA-based stall warning for recognition and reaction, and rewrite procedures and redirect training to include scanning the altimeter for loss of altitude, as part of the procedures for stall recognition and stall recovery? Is this a new idea that should be considered by all airlines and training facilities?

Perhaps you could pass this procedural good idea on to your airline’s training department and your pilot association’s training committee? By understanding aerodynamics, you can enjoy safe flying. Remember that $afety Pay$.

International Captain Paul Miller


More Questions Asked by Flight Crew Members Regarding AF 447

More questions have been raised by fellow safety minded pilots regarding AF Flight 447. Here are several:

1. Why were they flying through that nasty convective weather?

2. Why did the captain leave the cockpit just prior to the flight’s arrival to this area?

With respect to the questions asked, here is my take.

1. The captain had at least a 2 hour-old satellite pix by the time he started engines. The thunderstorm encounter occurred somewhere after about the second or third hour of flight, meaning that the AF 447 entered the thunderstorm area about four to five hours minimum after the satellite picture was taken. This means that it is very possible that the satellite picture that the captain received did not resemble the convective weather area that the flight eventually encountered enroute. This is assuming of course that the crew got a satellite pix at all out of Rio.  This is a very common pre-flight briefing problem for all airlines operating oceanic flights. Making the problem worse is that Flight Control is not required to resend the latest satellite shots to the crew during the flight.  Why is that? Why do we have rules that not only do not provide important weather information, but do allow the provision of somewhat inaccurate weather information? Why is that?

A. Let’s say that the captain was a cautious fellow and planned well. So he gets up a few hours before the hotel pickup, has a shower, checks his email, gets packed, dressed and meets the crew in the lobby. At the airport or maybe even at the hotel, he sees the satellite picture prepared and sent by AF Flight Control Dispatch Offices.

I have not seen a satellite pix or a weather observation from the time from 4-5 hours before the mishap, but if I was investigating this incident, that is the first place that I would look. Why? Well satellite picture is the information that will inform the captain as to what lies ahead of him and will inform his game plan, sleep strategy, crew switch strategy for the flight.  So my money is on a sat shot that shows widely scattered storms if any at all given to the captain during pre-flight briefings. He doesn’t see a threat at this time and doesn’t see any reason not to use his normal strategy of getting the oceanic clearance, getting the plane out onto the transoceanic tracks and then retiring to get some rest, letting the other crew members handle the routine of the crossing. This will allow him to get some sleep and be fresh when they get close to Europe and have to start their let down at CDG for landing. Maybe this is his normal routine. Based on this supposed scenario, it is a reasonable one.

B. Alternative scenario: The captain is a “show me” kind of guy; unless he sees the lightning flashes and is face to face with a thunderstorm, he doesn’t worry about the metro stuff, because it is all 4-5 hours old data by the time they get out onto the tracks for crossing.

Either way, I do not think that the captain foresaw that 60,000 ft+ inter tropical convergence zone storms in his path would be a real possibility.

Additionally, we might consider this: thunderstorms anywhere rise rapidly in height, developing at 2000-4000 feet per minute, even as much as 6000 feet per minute. Therefore, information such as “the previous flight got through this path” is not really all that valid information for following flights, especially flights following 10 to 15 minutes later.  The fact that another flight transited this area 10-15 minutes prior is certainly and in my opinion most definitely not an endorsement for safe flight in an area of active thunderstorm activity. Thunderstorms by their very nature are unstable. That is  what makes them so dangerous to flight. Thunderstorms violate the very first principle of aerodynamics, which says, “assume a homogeneous airmass.”  For sure a thunderstorm is not a homogeneous airmass!

Thunderstorm development in the inter-tropical convergence zone (ITCZ) is even more dynamic than at other places on the globe. This means that even more caution needs to be exercised in the ITCZ by commercial airline operations. Yet remember that this mishap occurred on a flight planned and operated regularly in the ITCZ by this airline.

C. Third scenario is this. This is the kind of fellow that does his own thing. He does the takeoff, then he does his nap, then he does his arrival. This is the way that he does things and this is his thing.  This is how he does every oceanic flight and he figures the other crew can handle things.  That is just the way he is.

D. Fourth possible scenario: The Air France Dispatch Office in CDG does not consider it their responsibility to update Air France flights with Air France passengers on board of dangerous weather that has developed and is now in the path of an Air France flight. They consider it their responsibility only to get the pre-flight paper work prepared and delivered and then do no further duties other than to stay awake and answer any questions that come up during the flight.

 

My guess is that AF Dispatch Flight Control Standard Operating Procedure SOP is not to initiate any inflight communications unless directed to do so by “higher authority” or some similar version of that idea. The second place that I would look were I doing the BEA investigation would be the AF Flight Control Log for AF 447, the AF Flight Control SOP and all of the metro data that was available to AF Flight Control before the mishap.

I would further examine just exactly how AF Flight Control does business every day and night with respect to how much info is passed to airborne flights concerning dangerous weather occurring ahead of any AF flight.

Sorry to say this but more than a few commercial flight crew members are like B and C. I am even more sorry to say that more often than not, many flight control offices are like D. They send company flights on flight paths that intersect dangerous weather and do not change plans along the way. My guess is that this most likely remains “the way things are” at many airlines. How about yours? Are you in a position to make some changes at your airline?

So that is some thoughts on question one. But if you are a good captain and a good communicator, my guess is that you also have a few ideas and I would be very interested in hearing from you and reading your thoughts on this same question.

Now for question two, here is what I think. I do not think that the captain was fully aware of what was ahead of him. I also do not think that the captain expected a failure on the pitot static system due to icing to occur if the flight did go into clouds.

Remember that the pitot static equipment manufacturer, France’s CAA, Airbus and AF all denied that the equipment was faulty, even though there had be several incidents of failure previously of this same equipment in this same scenario and that it had been reported in the industry press.

So that captain may have allowed himself to be informed by the “authorities” in lieu of informing himself through reading industry incident reports.

Again, there are plenty of crew members who allow themselves to be informed this same way, at airlines all over the world, pilots who do the same thing.

Those of us who doubt “authority” are few, probably less than 1/3 of all. My guess is that real doubters are even fewer than 1/3, more like 1/10!

So, here is a third question:  Why didn’t the captain jump back into his seat and take control as soon as he arrived back up front? I know that I would have. You? Sure things were confusing, alarms going off, icing, thunderstorms, panic-what better time for the captain to be in charge of the flight deck and the controls?

I hope that this mishap is eventually re-investigated by some board other than the BEA, a board that knows that they are doing a Safety Investigation and not a Legal Investigation for some future court proceedings.

In the meantime, I am blogging my thoughts to allow local safety managers around the world to think deeper about keeping their operation safe. That is my intent.

Keep in touch.