I am not really supposed to offer an opinion, but occasionally I do when it seems, with my mod hat on, that people apparently refuse to accept the meaning of words and go round in circles attempting to change the meaning of a word and creating angst. Forunately, to date it has all been controlled angst.
So, for those who require the meaning of the word doubt, in this case Collins Concise Dictionary and the word 'doubt.' It is thus:
1. doubt. uncertainty about the truth, fact or existence (esp in in doubt,without doubt, etc.)
2. (often pl.) lack of belief in or conviction about something.
3. an unresolved difficulty, point, etc,
4. Obs. fear.
5. give (someone) the benefit of the doubt. to presume (someone suspected of guilt) innocent.
6. no doubt, almost certainly.
In the case under discussion it would be correct, and yes, essential, that no one should try to change the meaning.
Where there is doubt there is no resolution. Where there is doubt there cannot be an answer (or did I just say that?) Where there is doubt only point 5 applies.
It follows that since no one knows what happened there must be doubt. Assumptions are invalid and it is willfully wrong to assume otherwise.
The regulations at the time state categorically that no doubt whatsoever must exist before passing a verdict of gross negligence on the pilots. Both Air Marshals were therefore wrong in making the pilots negligent. The House of Lords stated that.
Try as anyone might say otherwise. The FACT remains that doubt existed then as it does today and the pilots were NOT therefore negligent.