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fablarto

Flight Director?

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I've heard it mentioned several times that hand-flying with the FD on is a bad thing. However, I've never found a good reason why. What exactly does the Airbus FD do aside from displaying guidance on the PFD? I think I've read that turning off the FD will make the ATHR go to speed mode (thus not open mode). Is there something else fundamental that the FD actually does?Essentially, I feel like I'm not fully grasping the role of the FD - and if there's one thing about Airbuses, it's that you need to truly understand what the computers are doing!Thanks!Aldenbtw- my ch pedals arrived today! can't wait to go home and set them up!

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Hi,There is no reason to not handfly the aircraft with the flight director on as long as you intend to follow the commands. As soon as you switch off the autopilot the flight directors still guide you along whatever modes you have selected throught the FCU. That includes selected modes as well as managed modes. So leaving on the FD when flying the aicraft manually is no problem at all...as long as you the FD commands. When you really want to fly the aicraft manually ... like for example a visuale circuit without any guidance at all ... you should switch off the FD. Using the FPV (flight path vector) in that case can make flying the aircraft manuaully a little bit easier.Concerning the use of ATHR: when switching off the autopilot does not change or switch off the ATHR. It will continue to operate the same way as it did before you switched off the autopilot. You can even fly the aircraft with AP and FD off but still have the ATHR engaged .... in this case it will be only speed mode. But even in this case the speed can be managed or selected!So when it comes to your last question. No .... the FD's do not do anything different than your AP. They just move according whatever mode you have selected on the FCU. The only difference is.... when you have the AP engaged, the AP will follow the FD commands... when you fly the aicraft manually ... you will have to do it...Hope this answers your question.Cheers,Rob

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Thanks Rob,This helps a lot. However, I'm still wondering if there are any dangers with not obeying the FD commands when flying manually. I understand that the point of hand flying with FD on is to follow the commands. I would imagine that if one wasn't going to follow the FD commands they would just switch it off, but could there every be negative consequences of leaving the FD on and deviated significantly from the commands?I hope I'm not dwelling on this too much - just trying to really grasp it.Thanks!Alden

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Hi Alden,Technically or concerning the system there is nothing wrong with not following the commands. I mean .... it will not harm the system. However the flight directors are used to make the aircraft following a certain path. When you do not follow the commands the system just continues to try to get you on the correct path and you will end up with the FS bars completely off center. The system does not care .... but airtraffic control may not be so amused. And when it comes to deviations from the vertical path especially below you might find yourself on the ground .... or in the ground. That is bad for your health .... ;-)

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Thanks! This is exactly how I thought the FD worked, but I got confused. Thanks for clearing it up. -Alden

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