I don't think this will answer your question, but it might give you an insight:
Lt Stephen Kershaw
One of the issues that we had with the Buccaneer Rad Alt was that it was often unreliable below 50 feet and it would, more often than not, lock out at or below that height. Consequently, there was no method of knowing exactly how low you were or, worse, no further warnings if you were in a shallow descent towards terra firma. Unfortunately, and I am not saying this was the case in this accident, far too many aircrew were lost (in many more aircraft than just the Buccaneer) because they were concentrating too hard on other things, like finding and dropping bombs on the target, to be fully aware that the hard stuff was getting closer (before it was too late).
Very sad, I was on 12 Sqn at the time of the accident and it shook us all to the core.
Bloggs