PPRuNe Forums - View Single Post - AF 447 Thread No. 7
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Old 11th Nov 2011, 09:38
  #82 (permalink)  
Join Date: Jun 2009
Location: Germany
Age: 67
Posts: 782

2 PNF knew the PF was making inputs - Did they know which inputs he was making ?

Answer Old Carthusian
Yes by looking at the instruments. An input produces a certain pattern on your instruments and you can understand what your aircraft is doing.
Would you explain yourself in relation to the timeframe starting from 02:12:45?

Retired F4

Stick was full left, aircraft was banked to the right, how do you know by instruments, what kind of inputs are made by the guy in the dark 1 meter away?

Answer Old Carthusian
Retired F4
Both the PF and PNF have displays with the same instrumentation on them. Your artificial horizon will tell you if the plane is climbing or banking. You derive your rate of climb (or descent) or descent from your altimeter. Your bank rate from your rate of turn indicator. These are reliable and accurate instruments. They are not affected by UAS. Anyone who doesn't rely on their instruments ends up in a dangerous situation.
Why not answer my question, which you yourself raised with your answer? We are not talking about instrument flying and its carrying water to the sea to try to teach me how it is done. All of my 3.336 instrument approaches where handflown from start to end and successful terminated. Most of them in german wx conditions, not under the sun of california.

The discussion is about recognizing actions (not outcome) of handling flight control inputs in a non normal situation like AF447 was in.

I did lots of instructing in the backseat of the F-4. Our sticks had been interconnected and i could feel through critical maneuvers. Let us look at stall approaches, where a wrong flight control input lead to departure. On the stick the wrong input could be felt and corrective action could be taken immidiately and thus departure prevented, whereas on the instruments the faulty input would show later, when the faulty input had already lead to departure and uncontrolled flight. Better to be one step ahead than one step behind.

In the case of AF447 at 02:12:45 the PNF and the captain had been both aware of the right bankangle and gave instructions to the PF to correct that bank as they could not observe any action of the PF to correct this bank on the instruments. In reality the PF was aware of the same fact and told them, that he already had full left SS without success. That information was vital as it showed, that correction with aileron alone did not work and helped the captain to refocus on solving the bank problem with rudder input. It took considerable time to unmask this information and it was not visible on any kind of instruments.

The precise position of the stick is considerably less important than being able to work out that the stick is not where it should be. Once that is ascertained, then the only logical recourse is "I have control".
It can be assumed, that had the PNF took control of the aircraft prior receiving this information at 02:12:45, that he as well would have used aileron firsthand and would have lost valuable time as well.

I never said, that the SS should be replaced by a yoke, but i do not turn a blind eye to the fact, that in this stressfull situation the awareness of the crew concerning the behaviour of the aircraft in relation to the flightcontrol inputs of the PF was totally lost, that the captain was not able to grasp the situation when he came back to the cockpit and that the mentioned timeframe starting at 02:12:45 is a master example for the lack of direct feedback. Not that this is the only situation in these horrible 4 minutes, there are others as well. It is only a question of perspective.

Last edited by RetiredF4; 11th Nov 2011 at 09:58.
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