Never heard of it. Never used it.
Airbus P1, 4000+ hours on type.
Edited to add - checked the Airbus FCOM 3 and there is a reference there to AH of 100 ft. However in our SOP's we would initiate a go-around for any failure resulting in a warning, caution, Cat downgrade etc. below 1000 ft RA. Probably explains why the AH doesn't register.
Last edited by spin_doctor; 9th Jan 2009 at 15:05.