B777 VNAV Speed
Hello,
I am reviewing my training material with the goal of finding the exact behavior of the system, but I can't find my answer in the FCOM nor FCTM.
I find the following behavior rather annoying, hence my will to find exactly where it is described and study it thoroughly.
When selecting VNAV, the speed window blanks. The FMC now commands the speed.
What speed is going to be selected ? It depends on the flight phase.
The one phase that interests me is non-ILS approach. You're in ALT because you had to descend to platform altitude, which VNAV refused to do. Now you have to engage VNAV for an RNAV or VOR approach. The speed will move. I seem to recall that the speed can go to 240 or 170kt, but what are the exact speeds and conditions ?
I really don't understand why this choice was made. What's worse, even if we select speed intervention right away, by the time we've sufficiently rotated the speed selector, airplane IAS has increased around 10 kt and the flight is destabilized (large thrust variations). Is it donne this way in real life, or do some pilots temporarily disengage A/T to avoid that ?
Many thanks