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wijnand

AFS OVRD OFF

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Hi guys,I read this in the FAQ sextion (OPS) regarding the MD-11:"The two AFS OVRD OFF switches on the FCP below the AUTOFLIGHT button are NOT autopilot disconnect switches! These will completely disable the MD-11's autoflight system and you will not be able to reengage it. These switches should never be touched in normal flight operations. "What is the purpose of these switches ??Thanks,Wijnand (EHBK)

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This is completly untrue.In normal operations we don't use these switches, but if you want to trim the aircraft for example you can select both AFS OVRD down. If you switch the switches back to up, everything is working normally again!!The purpose of this switches is to disengage the Control Wheel Steering/Autoflight system and A/T. You can use it when the normal disconnect switches do not work. Some kind of emergency autopilot disconnect button :)

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From the AMM:

AFS OVRD OFF Selector (12) - Supplies an emergency autopilot/autothrottle disengage function to the flight crew. S. The AFS OVRD OFF selector operates as follows: (1) The autopilot is usually disconnected when the autopilot disconnect switch on the captain's or first officer's control wheel is pushed in. The autothrottles are usually disconnected when the disconnect switch on the number 1 or number 3 throttle lever is pushed in. The AFS OVRD OFF switches also supply an emergency disengage of both of the autopilot and autothrottle functions. (2) Each switch disconnects its related autopilot parallel mode autothrottle actuators. The elevator and rudder series mode actuator functions are not changed. The engine trim control function for the related channel does not change. An amber and gray diagonally colored bar is shown when a switch is in the shutoff position.

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>In normal operations we don't use these switches, but if you>want to trim the aircraft for example you can select both AFS>OVRD down. As soon as you hit the trim switches LSAS pitch attitude hold is disabled anyway, so no need for this at all.Markus

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I meant rudder and aileron trim. You want to disable CWS in this case.

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