Well hopefully that time will never come, or how could we pilots get lost?
I know that it requires lateral tracking. My surprise was when it was mentioned that with a HUD, it would automatically become CAT3B.
I know that for some aircraft it is basically like that.
For example, the Saab 2000 is able for CAT 3 hand-flown with a HUD installed.
And even that is CAT 3A.
Regarding CAT 3B operations, I fly the A330 and we use 75m rvr and no dh as minimums. The same thing is valid for our A320 fleet.
If we use it? Yes we do, but operationally, I've never encountered such conditions for real. In my opinion, CAT 3A is enough.
regards,