Originally Posted by
RetiredF4
NO, you are wrong there. It does maintain attitude, when autothrust is available. Without autothrust, when speed is decreasing, the aircraft trims to maintain the flightpath which is roughly 1 g.
What you describe would be a pure C law. My understanding is that Airbus uses a C* law. A C* law will progressively switch from g command to pitch rate command when the speed decreases, i.e. at the stall it will be mainly pitch rate. That means if no SS inputs are made it will keep pitch rate 0 which means constant attitude.
If SS is left neutral it should keep constant attitude throughout. That is also what BEA considers neutrally speed stable.
Could you point me to any source that states that Airbus instead is using a pure C law?
Edit: Altitude is not a parameter in any FCS law. So FCS alone will probably not chase altitude. It may chase g or pitch or pitch rate or speed. That is what distinguishes C from C* and C*U (B777).
Altitude is only an A/P parameter.