Sorry guys but I still don't really get it. Checkboard sort of makes sense to me but I don't know how that logic is deduced from the information in the Ops manual as I quoted it.
BOAC both ILS receivers continue to work from memory. Captain uses VHF NAV 1. F/O uses VHF NAV 2. It's a question of which pitch mode can be used during the ILS approach. If you try to use APP mode (ie pitch mode tracking the glide slope) the TR units are isolated at G/S capture and the problems begin.
rudderrudderrat, our B737's only have two autopilots so are only fail passive capable. We only just recently started flying to CAT II minimas too.
Is it possible to have only two autopilots and still be Fail Active capable? So if one autopilot fails, the single remaining auto pilot continues to fly the plane and is capable of autoland?? That doesn't sound right to me.