Originally Posted by
ACMS
The 777 crash in SFO was attributed to one on and one off wasn't it? The A/T stayed in HOLD ( at idle thrust ) and wasn't in SPEED mode.
Sort of...
At no stage were both FDs off at the same time, therefore the A/T remained in HOLD with FLCH SPD, & the PFs FD remained displayed throughout. Had they been cycled
both OFF, one ON the unnecessary guidance would have been removed, and A/T reverts to SPD mode.
The NTSB recommendation was to have FDs - plural - remain off on a visual, as far as I can see the Boeing FCOM/FCTM remains unchanged.
As for no guidance on a visual, the
theory is that the PMs FD reverts to sub-modes giving existing VS and azimuth so that they can
monitor proceedings.