Originally Posted by
sonicbum
Gobal speed protection :
If FDs are engaged in CLIMB or OPEN CLIMB mode or EXP CLB and the flight crew does
not follow the FD bars to maintain the commanded climb (pitch too low and autothrust in maximum
climb thrust), the aircraft accelerates.
Both FDs disengage when VMAX+4 is reached (VMAX being VMO, VLE or VFE). If the A/THR is
active, it reverts to SPEED mode and reduces the thrust to recover the speed target.
A triple click aural warning sounds.
FDs are engaged in an OPEN mode in descent with the AP not engaged.
If the FDs are engaged in DES, or OP DES mode, or EXP DES and, if the flight crew does not
follow the FD bars to maintain the commanded pitch, the aircraft decelerates (insufficient descent
rate and idle thrust).
If the airspeed reaches VLS-2, both FDs disengage. (If speedbrakes are extended, the FDs
disengage between VLS-2 and VLS-19, depending on the position of the speedbrakes).
The A/THR, if active, reverts to SPEED mode upon FDs disengagement, and increases thrust to
recover the speed target.
A triple-click aural warning sounds.
Yeah, I know. Should not have used "protection", I should have said that if you are hand flying visually and select V/S instead of open descend/climb the AT will maintain your selected/managed speed if you reduce pitch down, and similarly, it will maintain speed if you reduce pitch while you climb.