Cheers guys, thanks for your replies. I've always done two on the nose and two on the main as you suggest but at the airport I work at we've been told we now have to stick 12 (yes TWELVE) chocks on all nightstopping a/c, even in calm conditions! Just wondered what the rest of the aviation world did... And Grizzler, glad you haven't lost one yet as imagine the boss's mood if they came in one morning to find a raydome stuck in the terminal!