Does anyone have any information on the autothrottle wakeup feature of the B747-400? I wasn't aware that it even existed on the 744, but a respected sim instructor is certain that it does, at least in the simulators he used. I can't seem to find anything in any of my manuals. I'm referring to when the A/T is armed at the MCP but disengaged with the throttle switches and will come alive in SPD mode (FMA) when the speed gets low.
Did Boeing add this feature later, possibly as a result of the Asiana 777 crash (even though this feature wouldn't have prevented it anyway). Maybe the paragraph in my Vol. 2 below is referring to this feature, but it is difficult to tell if this is a wakeup feature or if it is assuming the A/T is already awake.
The autothrottle and AFDS independently provide speed protection for all operations except during V/S pitch mode or engine failure above maximum engine-out altitude. Autothrottle speed protection is limited by the reference thrust limit (CLB, CRZ, CON, etc.) and idle. AFDS speed protection is provided through the elevators in the following pitch modes: VNAV SPD, FLCH SPD, or TO/GA.
Thanks.