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Cirrus22

Question about a 744 youtube video

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Hi all,Was looking it this video:

The aircraft is on AP with APP engaged until about 70ft, yet the captain is moving the control column quite a bit - why is he doing this? Shouldn't such inputs disengage autopilot?Thanks!

<a href="http://www.flyaoamedia.com"><img src="http://angleofattack.s3.amazonaws.com/blog/wp-content/uploads/2010/09/aoasiggy.png"/></a>

Nick Collett

i5 2500k @ 4.4GHz, GTX 480, 8GB Corsair 8-8-8-24, 300GB WD Velociraptor, Corsair HX850W

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Hi all,Was looking it this video:
The aircraft is on AP with APP engaged until about 70ft, yet the captain is moving the control column quite a bit - why is he doing this? Shouldn't such inputs disengage autopilot?Thanks!
Not when in APP mode./ Leffe

Leif A Mikkelsen

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That makes sense. Why the control inputs with AP engaged though?
I don

Leif A Mikkelsen

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Does AP move the yoke itself? Or was he moving it as he would if AP was disengaged?
AP moves the yoke, just like in our PMDG 747/Leffe

Leif A Mikkelsen

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I've always got my hand following the yoke when flying a coupled approach, I thought all pilots did this. Maybe I don't understand the question.


Dan Downs KCRP

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I've always got my hand following the yoke when flying a coupled approach, I thought all pilots did this. Maybe I don't understand the question.
Your correct Dan, I think Nick was not aware the autopilot moved the yoke. Nick if the pilot had tried to fight the autopilot through the yoke you would have heard the Autopilot disconnect, you have to exert quite a bit of force to override the autopilot. He was just following the movements of the yoke in case the autopilot did something stupid and he had to take over.

Rob Prest

 

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Its normal and required practice to cover the controls like that on an aproach, what you cant see on the video is as he got closer to the ground his fingers would be covering the AP disconnect and the TOGA buttons incase something dropped out or a go around required. In fact there is a written limit in ther MEL to the lowest you can fly with the autopilot engaged with an AP disconnect or toga swith U/S, I think off the top of my head its 1,000ft.cheersJon Bunting


747-400 captain. 

Technical advisor on PMDG 747 legacy versions QOTS 1 , FS9 and Aerowinx PS1. 

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I think Nick was not aware the autopilot moved the yoke.
Correct - I had no idea! I'd assumed that, unlike with a light aircraft where the controls are linked directly (without the aid of hydraulics) to the control surfaces, the yoke wouldn't move. Is this servo controlled (like the thrust levers with AT engaged), or would the yoke move if someone were to physically move the actual ailerons/elevator? Similar to what one might do in a light aircraft preflight.

<a href="http://www.flyaoamedia.com"><img src="http://angleofattack.s3.amazonaws.com/blog/wp-content/uploads/2010/09/aoasiggy.png"/></a>

Nick Collett

i5 2500k @ 4.4GHz, GTX 480, 8GB Corsair 8-8-8-24, 300GB WD Velociraptor, Corsair HX850W

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The smallest thing I flew with an A/P was a Cherokee, and the yoke moves with the autopilot flying. It has to, there is not a separate control surface for otto.By the way, the 747 uses direct mechanical linkage between yoke and surface too, just adds a little 'power steering.' If you move a control surface, the control moves with it.The a/p servo is in the mechanical linkage, and they are true servos with feedback loop control.


Dan Downs KCRP

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Correct - I had no idea!
If only we had "force feedback" yokes/throttles for our PCs that can keep the yoke/throttle in sync with the AP/AT, now that would be something!

Matthew S

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