This may be a rare occasion in which I agree with PW 100%!
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In fact if I remember correctly, there was -1 to hit modifier per 10" something moved. So a Genestealer (M6) that used its run move was going 12" - -1 to hit. And when they introduced overwatch (in a WD I think) that applied as well.
So a flyer going 36" would be -3 - seems reasonable.