Catching a late sink by manual thrust in an A330.

[Uplinker]

@dogsridewith; I don't know because I never let it get to that.

There used to be an Airbus approved procedure called Phase Advance, which was to be used in those instances where the Autothrust was being 'lazy' on approach, and/or on hot thermally days, and allowing the speed trend to drop into Vls.

To engage Phase Advance, one simply pushed the thrust levers just forward of the CLB detent - NOT into TOGA, NOT even as far as MCT, but just out of the CLB detent.

Doing so disengages A/THR, (but it stays armed), so the FADECs increase engine thrust towards where the thrust levers are now set, i.e. just above CLB thrust. After one or possibly two seconds, you return the levers to the CLB detent. So the action is: Push about a centimeter, (click)*, then after one second pull back into the CLB detent, (click), upon which the A/THR re-engages.

This procedure increases engine thrust a little, (not all the way to above CLB), which is usually all that is needed, and it works well. BUT the A/THR does NOT re-engage below 100', so in this case you would have to manually control thrust into the flare and landing. However, Airbus have removed the procedure from the manuals, and there is no mention of it anywhere.

I recently did this purely instinctively on an A320 when the speed trend arrow went deep into Vls on short finals, (I was used to using phase advance on A330s on approaches on hot thermally days), although it is no longer an approved procedure.


* The (click) is the sound the lever gates make, you are not clicking any buttons.