Originally Posted by GMDS
[...] but add a moving throttle [to the airbus flight controls].
This may also have been lost in the over-long thread, so I'll repeat that there are at least two arguments for static thrust levers, and against moving ones. And I will not be the judge whether or not these effects of the A320 design provide a more substantial (safety and convenience) advantage than the one ostensibly gained by adding movement.
- Alpha-Floor-Protection:
This feature sets TOGA thrust when exceeding a pre-defined angle of attack, to keep the aircraft from stalling (coupled with an enforced limit on the angle of attack that the pilot cannot exceed even at full backstick deflection.)
Pilots used to a moving-lever design desiring low-thrust would perhaps automatically reach for the thrust levers and pull them back if they quickly moved from a low setting to TOGA, denying them this form of flight envelope protection. Setting TOGA thrust without moving the levers gives the pilots one more second to think before cancelling utothrust, and thereby unlock TOGA thrust.
This argument may seem a bit far-fetched, but may happen more often than the scenario in this accident, which so far has occured at a rate of once per 17 million landings.
So I ask again if anyone knows about the number of times Alpha-Floor-Protection has been activated? Isn't this such an abnormal situation that it should be logged?
- Limiting thrust during Autothrust operation
The levers provide a simple and intuitive means to limit thrust on an engine producing excessive vibrations, while having maximum power available on the other engine.
Having "split" thrust levers is abnormal, so the ECAM will warn about it, but only in amber, meaning "
this is not the normal way things are done, but it may be desired, so I won't make a big fuss about it, but simply tell you."
Mandating a change to the thrust lever system would have to prove that the gained advantage outweighs these (and probably other) advantages of the current design. This has not been shown.
Bernd