Radalt / TAWS requirements
I've been wading through the books trying to get my head around TAWS / EGPWS system requirements.
So far as I can tell, the regs require a TAWS, at A or B level functionality for aeroplanes or helicopters over a given size. It is normal to include a radalt feed into the system, but not strictly required - although so far as I can tell all aeroplane systems and most(?) helicopter systems do include a radalt feed.
Also so far as I can tell, there's no requirement for duplication of any part of a TAWS system, including of the radalt?
Do I read this correctly, and if I'm wrong, is anybody able to point at the regulations that prove me wrong?