>> Autothrust
Please can a 777 driver explain the A/T. Only 777 please.
Why if the A/T is engaged would the speed decay below target speed. On the Bus with FD off the the AT will follow the speed bug. On Thrust Idle open des the throttles remain at idle.
Which mode would allow the AT to go below target speed.
AT is usually always engaged.
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Wow... just had a mini epiphany. It would be great for a 777 pilot to chime in on the following thought...
The 757/767 auto-throttles go into THR HLD and won't "wake up" till they capture the GS when APP is armed (as I recall... don't have the systems manual handy at the moment.) If the ILS is out of service and the pilot does not select SPD on the A/T panel, the thrust levers will remain in HLD waiting for the "capture". Perhaps this small bit of automation confusion led the Asiana pilots to falsely believe the speed would be protected when in fact the thrust levers will remain at idle (waiting for the capture.) I'm wondering if the 777 has a similar auto-throttle logic?
Where I've seen this occur most is a manual descent where the pilot flying shallows his rate of descent to 100-200 VVI and airspeed decays below target because ALT CAP has not occurred (till approximately 20-50 feet above level off.) I always warn new pilots (to the fleet) to remain vigilant whenever they see THR HLD, and always mentally confirm a capture and wake up of the auto-throttles.
Just thinking out loud why the airspeed decayed so significantly (according to an initial NTSB briefing.)