A320 Autothrust
 

Hello

if you keep the "instinctive a/thr disconnect p/b" pressed for more than 15 seconds, autothrust will be unavailable for the rest of flight (irreversible action).

Now my question is: why has Airbus implemented this feature?
Is there any abnormal condition (of the A/THR) that dictates the use of this option?:confused:

thanks
B_D

If you dispatch without auto thrust, this action is required after start to prevent any unwanted thrust adjustments.

A note at the bottom of FCOM DSC-22 30-90 P 5/12:

If the flight crew pushes and holds one instinctive disconnect pb for more than 15 s, the A/THR system is disconnected for the remainder of the flight. All A/ATHR functions including ALPHA FLOOR are lost, and can be recovered only at the next FMGC power-up (on-ground).

I understand that to mean that if you have inadvertent ALPHA FLOOR activation due to faulty AOA indications, you can stop it.

I guess that it is just a safety feature, if the a/thrust is not acting as you require it too you need some way of disabling it for the remainder of the flight so you are not constantly having to push the disconnect button every time it has a wobbly. Same theory with the sidestick takeover pushbutton, if you hold that for an amount of time (30seconds I think) then the other sidestick is 'locked' out for the remainder of the flight, once again that would be a very handy feature if you develop a side stick fault.

The sidestick can of course be re-activated in flight, if required. However the AT when pressed for more than 15 seconds can not be recovered in flight. Well worth remembering that Alpha Floor etc is also lost.