Small variations in my company/aircraft:
We have two breakoff possible:
45¡ with 35 seconds
30¡ with 50 seconds
Time after "abeam threshold" 30 seconds, wind correction -1 second/2 knots tailwind (no headwind normally as mainreason for circling is to have the wind on the nose when on final).
Tolerance on MDA or circling altitude +0/-100
All in all a very enjoyable and challenging manoeuvre to fly (try GEN at nite with northely winds)
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... cut my wings and I'll die ...