Originally Posted by
Uplinker
I don't know Boeing but on the ? 777 PFD shown in this thread; during FLCH mode, the Autothrust 'speed' annunciation seemed to move over to the pitch box leaving the top left speed control box blank.
So I wonder is there a danger that since 777 pilots get used to seeing a blank box top left when the Autothrust is still operating, this might lead to some missing the clues when the Autothrust is actually off for real?
The SPD annunciation moves over to the vertical FMA box because the speed is now being controlled by pitch rather than the autothrottle.
I'm not really sure why in this video the autothrottle has been disconnected (Blank box) - if you're flying along and hit FLCH, you should get either THR or IDLE then HOLD depending if you're going up or down.
A blank left FMA box indicates exactly that – the autothrottle is NOT operating. If in a vertical mode other than FLCH SPD, however, the autothrottle, if armed, can still "wake up" and provide stall protection; this is what brought Asiana undone.