The Innsbruck air traffic controller seemed to be a sort of funny bone: „Bye D-5707, you’re cleared for course west, altitude 11,500 ft and below“. As it happens I have a sort of calculating disability concerning Imperial Units. Only after I switched the flight computer I found out what this meant… Check the picture: altitude 10,000 ft and there wasn’t a lot of head room anymore – definitely not another 1,500 ft.