Originally Posted by Flight Safety
When auto thrust is engaged on the A320, switch arm positions CLB, FLX, and TOGA are available as possible selector switch positions.
To be nitpicking, this is not strictly true. Above CL position, thrust lever position always directly selects thrust. (Above MCT with one engine out.) But I take your point.
In selector switch mode, lever position no longer equates to engine power thus the levers have no direct control over engine power, because they no longer function as throttles in any classic sense.
Even with A/THR engaged the thrust levers function as limiters (perhaps throttles, really), limiting the maximum thrust A/THR may set. Since this is rarely used, thrust levers may seem to be working more as a selector than a throttle during flight.
Perhaps not.
At least one A320 pilot (TyroPicard) said he did not think of them as mode selector switches, but rather thinks of selecting idle thrust when pulling them back at the flare. Others may feel different. I cannot judge that.
I also agree with him that most of the times you actually touch the thrust levers, they work as throttles. As long as they stay in CL and A/THR is active, they're not used, and not thought about much.
Typical thrust lever movements are: Using low thrust during taxi, setting medium power to stabilise engines, setting T/O thrust, reducing thrust at acceleration altitude, retarding to idle, selecting reverse idle, selecting max reverse, back to reverse idle, back to forward idle, low thrust for taxiing. (I also count 10, 12 if you count setting and reducing taxi thrust as two movements, more if you do it multiple times.)
In all cases in which you move the levers, thrust actually changes in the direction of lever movement. For all intents and purposes these are throttle levers.
Modes exist where the same gesture (control action) yields different results depending on system state at a time when your attention is not on system state.
Here's a problem with your reasoning:
Pulling the thrust levers to idle yields the
same result, regardless of autothrust being engaged or not: it selects idle thrust. So by your own admission, this is modeless.
Bernd