Originally Posted by
Rocade
One thing that I've wondered about for awhile:
Descending using FLCH, the throttle goes to idle. In the descend, select VS mode and speed bugged down, the auto throttle goes from fully idle to adding a little power (though still less than idle with engine AI on).
Anyone know the logic behind this? A quick scroll through the FCOM didn't provide the answer...
20 years on the airplane and I never knew why it does this. Boeing produced the 757 for 20 years and in a way still does the 767-300F. They never did any upgrades to the Auto-flight system (A/P, A/T). The 757 Autothrottle is a pretty poor system.