Originally Posted by
skkm
When both F/Ds are turned off, the FMAs will be blank and no (vertical/lateral) modes active. When a F/D is then turned on, it has to go to some default mode. With wings close to level (<5º bank), that will be TRK HOLD | V/S; beyond 5º it will be ATT | V/S, to approximate the existing flight path until other modes are selected.
Thanks a lot, that's exactly what i want to learn, could you give me more details or where i can find more? by the way, when the v/s mode activity, will it be changed by attitude changed? or just stuck at the moment when turning one side FD on?