HIGH SPEED PROTECTION
When flying beyond maximum design speeds VD/MD (which are greater that
VMO/MMO), there is an increased potential for aircraft control difficulties and
structural concerns, due to high air loads. Therefore, the margin between
VMO/MMO and VD/MD must be such that any possible overshoot of the normal
flight envelope should not cause any major difficulty.
High speed protection adds a positive nose-up G demand to a sidestick order, in
order to protect the aircraft, in the event of a dive or vertical upset. As a result,
this enables a reduction in the margin betwen VMO/MMO and VD/MD.
Therefore, in a dive situation:
. If there is no sidestick input on the sidestick, the aircraft will slightly overshoot
VMO/MMO and fly back towards the envelope.
. If the sidestick is maintained full forward, the aircraft will significantly overshoot
VMO/MMO without reaching VD/MD. At approximately VMO + 16 / MMO +
0.04, the pitch nose-down authority smoothly reduces to zero (which does not
mean that the aircraft stabilizes at that speed).
The PF, therefore, has full authority to perform a high speed/steep dive escape
maneuver, when required, via a reflex action on the sidestick. In addition, the
bank angle limit is reduced from 67 to 40 degrees, which minimizes the risk of a
spiral dive.
Note:
1. An OVERSPEED warning is provided.
2. At high altitude, this may result in activation of the angle of attack
protection.