CDA approach, thrust setting at flt idle almost till stabilized.
B777, with one Autothrottle Arm Switch off, there is an Eicas Msg.
Now get this, with both Switches off together, NO Eicas msg the last time I tried. Possibly modified by now.
Could both switches be accidently knocked off without anyone noticing until the autothrottle needed to maintain speed.
Then again fm idle to full power takes 8 secs if throttle was advanced manually.