Have to agree with Ascend Charlie & Shy Torque
When I was a bograt
and even up until I joined offshore, I spent countless times doing compass swings in machines at Bankstown airport and elsewhere.
They actually had a compass swing area near the main pad at Bankstown for those that flew there such as Ascend Charlie.
These were done engines running with the ginger beer and his compass thingy pointed at us when we gave him the thumbs up, but we used to have to keep it light on the skids on compass heading each time.
