walter kennedy,
I see that you have changed your original theory and decided that the crew were ordered to carry out this "trial" of US Navy equipment which is why they were on that route at low level.
Well, there is a very easy way to prove whether you are right or not.
You may not have noticed, but the writing on the photocopied chart left behind at Aldergrove belonged to neither of the 2 Pilots involved in the accident.
The chart was drawn up by the RN Captain of the other detatchment crew because he assumed that crew duty considerations would require the use of both crews to complete the days tasking.
Thus, there is someone who can give a categorical "YES" or "NO" to your theory that the crew were detailed to carry out such a trial.