A330/A340 General Information
REV 1 (6 JUN 05)
FCTM  Flight Controls

These features are aerodynamic protections. Additionally, there are three energy features that enhance these protections:
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With the A/THR engaged, the aircraft will not decelerate below VLS (displayed as top of amber strip) even if the target speed is selected below VLS.

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A low energy aural warning is triggered when the aircraft energy level is below a given threshold. This energy level is a function of several parameters including aircraft configuration, speed, horizontal deceleration rate, flight path angle and altitude. (FCOM 1.27.20 refers) The aural warning "SPEED, SPEED, SPEED" alerts the pilot of the requirement to adjust thrust and flight path. It is triggered during deceleration before Alpha Floor (unless Alpha Floor is triggered by stick deflection). The delay between the aural warning and Alpha Floor activation is a function of deceleration rate.

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If Alpha Prot is reached and the pilot still maintains aft sidestick, Alpha Floor protection (set between Alpha Prot and Alpha Max) will be reached. This protection triggers the application of TOGA thrust and the aircraft will start to climb at a relatively constant low airspeed. Alpha floor protection is inhibited in some cases. FCOM 1.22.30 refers.

The aircraft can also enter alpha protection at high altitude, where it protects the aircraft from the buffet boundary. The PFD shows that alpha protection is active in the same way as at low speed and low level: the amber and black strip rises to the actual speed of the aircraft. As at low speed and low level, if the stick is merely released to neutral the aircraft maintains the alpha for alpha protection.

A330/A340 2.60.7 Flight Controls
FCTM REV 1 (6 JUN 05)
Load.Factor.Protection
On most commercial aircraft, the maximum load factor range is 2.5g/.1g clean and 2g/0g with slats and/or flaps extended. The load factor protection is designed to maintain the aircraft within these limits while allowing the crew to consistently achieve the best achievable aircraft performance, if required.
On commercial aircraft, high load factors are most likely to be encountered when the pilot responds to a GPWS warning. Airline pilots are not accustomed to using "g" as a flying parameter and experience has shown that, in emergency situations, the application of "g" is initially hesitant and then aggressive. If a GPWS alert is generated which requires an immediate pull-up, full back stick should be applied and maintained. The load factor protection will allow maximum "g" to be achieved in the shortest time while preventing the aircraft from being overstressed.

2.60.8

A330/A340 General Information
REV 1 (6 JUN 05)
FCTM Flight Controls

CIFT.Escape.Manoeuvres.on.Protected.and.Non-Protected.Aircraft

High.Pitch.Attitude.Protection
Excessive pitch attitudes, caused by upsets or inappropriate manoeuvres, lead to hazardous situations. Even the most extreme emergency situations do not require flying at excessive pitch attitude. For this reason, high pitch attitude protection has been designed to be part of the flight control system. The high pitch attitude protection limits the pitch attitude to +30°/.15°. The 30° limit decreases to 25° at low speed. If the aircraft approaches these limits, the pitch and roll rates start to decrease 5° before the limit so that it will stop at the limit without overshooting.

High.Speed.Protection
Beyond the maximum design speed of the aircraft, VD/MD (which is greater than VMO/MMO), there are potential aircraft control problems due to high air loads. Therefore the margin between VD/MD and VMO/MMO must be such that any possible overshoot of the normal flight envelope does not cause controllability problems.
In order to protect the aircraft from dangerous phenomena at high speed, a positive nose up "g" demand up to 1.75g is added to the pilot demand on the sidestick when exceeding VMO/MMO. Additionally, if the side stick remains forward, the sidestick nose down pitch authority is smoothly reduced to zero at approximately VMO + 16/MMO + 0.04. With reference to the diagram below, if a dive is achieved with stick free, the aircraft will slightly overshoot VMO/MMO and fly back into the flight envelope. If a dive is achieved with the sidestick fully forward, the aircraft will significantly overshoot VMO/MMO but without reaching design speed limits, VD/MD.
　
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