It's a description of events created by a human source with direct personal knowledge of those events.
It's a description of events - true, he's been on the flight he describes. He then comments on matters 'beyond his expertise'. He is reporting - for, after all, he is a reporter - what he is told about the capabilities of the V forces. That may or may not be true.
Any competent historian would have no difficulty in distinguishing between the two.
Not quite the same as reading VCAS's files in the PRO. But then, if you don't know the difference, you end up saying silly things like the UK assassinated Franz Ferdinand ...