what was it that the microlights were doing wrong?
They weren't doing anything legally wrong, I said that. It
might have been conisdered "better airmanship" had they chosen to speak to the airfield whose approach they were flying through,
if they had radios, but as we know
(1) they were perfectly within their rights not to do so
(2) doing so would not have guaranteed separation.
(As I didn't take the foggles off or peek I don't actually know how close we came, and of course I haven't a clue whether they saw us or not.)
If they didn't have radios it
might have been considered "better airmanship" for them to have chosen to be higher or lower than the normal instrument approach path...
... however ...
... it wasn't until I started instrument training that I began to learn at what heights aircraft would be at what range on the instrument approach, and as well as not having a radio tuned in to Cambridge they might not have had a DME tuned in to Cambridge, so actually
I'm at a loss to understand how it is reasonable to expect a VFR pilot (in
any type of aircraf)
to know at what height to avoid crossing the instrument approach, and it seems unreasonable to expect them to avoid an entire ten-mile wide chunk of countryside.
Should PPL (and microlight and glider ect ect) training include teaching people "if you're x DME from the threshold don't cross the instrument approach between y00' and z00'"? - I'm sure it doesn't for most people at present, certainly I was never taught that.
[Of course it is possible that they didn't know they were crossing an instrument approach path because they didn't have maps or didn't look at them, in which case they would have been doing something wrong, but I've no reason to suppose that this was the case.]