Let's hypothetically say that somebody is being charged as discussed, and it's by the CAA.
Now, if the CAA are unhappy about something, they have the full force of the organisation behind them. This means that if anybody is capable of finding an ANO infringement, they'll have done so.
So, if the charge does not include any ANO infringement, but ONLY reckless endangerment, this implies to me that they couldn't find one.
So, your barrister would probably conduct a discussion along these lines in court:
Barrister: "So, Mr CAA, you've reviewed the ANO, manuals, licencing regulations and so-on, and you've not charged my client with any breach of any UK regulations".
CAA: "That is correct, we've charged him with reckless endangerment"
Barrister: "So, you are saying that it is possible to recklessly endanger the public by fully complying with CAA regulations".
That, pretty much, was the course by which the chap I helped out got off his CAA sponsored criminal prosecution. And, in my opinion, appropriately so (albeit that the discussion above actually ran to about 7 hours).
G