PPRuNe Forums - View Single Post - AF 447 Thread No. 6
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Old 25th Oct 2011, 02:11
  #1399 (permalink)  
Machinbird
 
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Someone mentioned that the SS does offer feel. Yes, it does offer feel, but not feedback. Maybe I'm just "ham handed", but the feel offered by the Airbus SS is of little value to me. Once you break out of center, I don't feel much difference between part and full deflection. But more importantly, the FBW system prevents me from feeling the controls I.e. "feedback". In an MD80, I can feel a wing start to drop (thru the yoke) before it happens. In the Airbus, I have to see the wing drop on the ADI, make a corrective control movement, watch the ADI again to verify the control was successful. IOW, with feedback, I never had to think or process a control input. My hands felt the controls and sent the message straight to flying part of my brain which returned the correct input to the control yoke. No cognitive process involved.
TTex600, I could be wrong, but what I think you are perceiving is the time lag in your perceive-act cycle. An aircraft like the MD-80, you see the slightest of movement and you apply the slightest of pressure automatically and the wings stay level. If you have to perceive a bit of movement, and mentally process it, before making a correction on the 'Bus, then the response is going to be a bit delayed.

One of the early visual flight simulators for the A-4 Skyhawk had a bit of lag in the visual display of about 0.3 seconds. No problem to fly it 'visually' as long as the control movements and rates were small. But if the rates were high enough, the lag caused a disconcerting overshoot and could generate a PIO, normally in the roll axis. This may be an analog to what the PF on AF447 experienced in Alt 2 law with the higher than accustomed roll rate.
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