PPRuNe Forums - View Single Post - AF 447 Thread No. 7
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Old 20th Dec 2011, 00:16
  #689 (permalink)  
Machinbird
 
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Originally Posted by OC
I have stated earlier that I see merit in your suggestion but that I see it on a mechanistic level - an explanation of how the phenomenon worked but not a casual factor. This is my main objection to the paper you linked. It was too vague and too inclusive. The phenomenon wasn't adequately defined (it could be anything seemed to be the message) and it seemed to want to attribute an overly deterministic approach to a pilots actions. In other words the pilot was not responsible for his actions and a helpless victim of PIO. One is forced into the question why have pilots then? Are they truly unable to take decisions and judge a situation? I tend to believe that a pilot has responsibility for his/her actions and that a statement like 'is not the fault of the pilot' (Conclusion No. 3) is just as dangerous and misleading as 'is the fault of the pilot'.
OC, lets try the following concept on for size. Don't worry how the situation occurred, just how the pilot handles it once discovered:

As you lift off the ground, the aircraft rolls the wrong way in response to your roll inputs. If the pilot is not able to override his natural tendency to correct a roll to port by moving the stick to the starboard side of the cockpit, is it then his fault that the aircraft crashes? Shouldn't he be able to rewire his brain on a moments notice to reverse the response? That is exactly the situation a pilot facing PIO encounters. His learned responses don't quite fit the situation any longer. If you encountered this type of situation, would you also be able to remember your aerobatic training to put the stick forward while inverted to keep from losing altitude? This is similar to the kind of control problem the AF447 PF may have faced (albeit a bit more extreme.)

Originally Posted by OC
If BEA do not reference PIO as a factor it won't be because they have an agenda but because they don't consider it germaine. That too is a legitimate judgment.
The roll behavior after the autopilot dropped is extremely anomalous. If BEA does not address why it occurred, then they would be putting their heads in the sand. There would be a lot of people asking hard questions then.

3.
PIO is an event that results from faulty aircraft design, extension of the airplane’s operational usage into an area for which it was not intended, or following a failure, and is not the fault of the pilot.
This is the paragraph that you are objecting to. PIO really is a design problem and can be tailored out of the control system if known. If there was not a test point that stimulated the PIO tendency in that corner of the envelope, it may not have been uncovered during the flight test program and subsequent line flying. PIO is very dependent on pilot technique. For example, if a pilot is attempting to damp out a rate of motion, his control strategy is different than if he is attempting to hold an attitude.

Saying that PIO is not the pilot's fault is not the same as saying that PIO is not the pilot's problem. As you well know, when airborne, there is no one available to save you from your predicaments but you. By saying it is not the pilot's fault, the paper indicates that is up to the airframe maker and certifying authority to evaluate the problem and ensure necessary corrective action.
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