Am I right though in thinking that you must have an ADF to fly an NDB approach?
From a few years ago, I recall reading an analysis of the then UK regs, and in Class
G it was unclear that you had to carry an ADF for flying an NDB approach. The approach plate merely shows a navigation path to follow; it does not say you have to use those instruments. (In the USA, I recall, it was thought mandatory to carry the kit implied by the plate).
For a Class
D airport it was clear enough because it is CAS and you are obviously IFR so the
enroute equipment carriage regs deal with the issue.
It is possible that the reason the CAA is clearly deliberately dragging its feet on removing the
enroute ADF requirement (IFR in CAS) is because there is no reg specifying equipment carriage when flying an
approach. They would have to add one into the ANO, otherwise they would be opening an obvious and highly visible hole enabling the use of "any" GPS for all approaches.
Still using them in my A320 today!
I know you have to carry an ADF but precisely how and when do you use it for navigation?