Aircraft Recognition
In the early 60s, the fighter force had weekly aircraft recognition tests in squadron, with a monthly test sent to Group for marking.
We had to note the wingspans of each test aircraft, so that we could set the wingspan of our intended targets into the gunsight.
One of our number declared that this was b**ll**cks, as all we need to know was if the aircraft was theirs or ours and if it was big or small (all bombers had 50ft wingspans and all fighters had 30ft, approx).
So, on the next Group test, he answered "Theirs small", "Ours large" etc. The results of the test came down with the AOC's comment, "If Flt Lt Bloggs persists in this novel way of identifying aircraft, he will have my large up his small."
End of innovation.