VMO/MMO EXCEEDANCE
In turbulence, during climb, cruise or descent, the aircraft may slightly exceed
VMO/MMO with the autopilot (AP) engaged.
To prevent such an exceedance, adapt speed or Mach target.
If severe turbulence is known or forecasted, consider the use of turbulence speed.
If the current speed is close to the VMO (maximum operating speed), monitor
the speed trend symbol on the PFD.
If the speed trend reaches, or slightly exceeds, the VMO limit:
. Use the FCU immediately to select a lower speed target.
If the speed trend significantly exceeds the VMO red band, without high speed
protection activation:
. Select a lower target speed on the FCU and, if the aircraft continues to
accelerate, consider disconnecting the AP.
. Before re-engaging the AP, smoothly establish a shallower pitch attitude.
If the aircraft accelerates above VMO with the AP engaged, the AP will disengage
on reaching the high speed protection. The high speed protection will apply a
nose-up order up to 1.75 g, in addition to pilot input during VMO recovery.
Therefore, make a smooth pitch correction in order to recover proper speed.
Speedbrakes may be used in case of high speed exceedance, but the flight crew
should be aware of pitch influence. In addition, speedbrakes will be used with
caution, close to the ceiling.
High Speed Protection may also result in activation of the angle of attack
protection.
In all events, check the AP engagement status, and re-engage it when
appropriate. It may have tripped and the associated aural warning may have
been superseded by the overspeed aural warning.