When shooting a CAT II or III approach, Why is it so important to discontinue the approach if the standby altimeter shows a flag?
Type, L1011, standby altimeter is not required for CATII/III.
Likewise, standby ATT indicator is not required for CATII/III.
However, for flight dispatch requirements, both must be serviceable for planned IMC flight. Failure in flight is just that, a failure, neither affects the landing capability.
777 has got 3 autopilots or channels quite amazing indeed.
Cheers
Even more amazing is the L1011, two dual channel autopilots (IE; dual/dual ), for fail operational performance.
An old aeroplane, yes, but quite capable, even today, if maintained properly.
Fully CATIII certified, out the door, circa 1972.