Question for you gurus. For the newer aircraft that have the "BKUP SPD/ALT" buttons. We recently received an aircraft with these buttons installed; it is in the FCOM but not represented in our simulators.
How does this work exactly? According to the FCOM the captain or first officer can independently activate the BUSS on their respective PFD at any time by pressing this button, and it is reversible.
I assume that if you just reach down on a normal day and hit that button, the PFD simply displays the BUSS information in lieu of the normal (stilll functioning) airspeed and altitude tape, without affecting the flight control laws or ADRs in any way. Yes? No? What about the autoflight system? If for example AP1 is engaged and the captain decides to "see what that button does" does it kick the autoflight off, or does everything continue to function? FCOM PRO-ABN-NAV section references a couple of ECAMs the simply say "AP 1 (2).... DO NOT USE" which sort of sounds like they dont go away on their own.
Anyone actually used this thing yet?