Which would be redefining "circuits". So the flights don't "all involve an
equal number of takeoffs and landings".

How so? Is there an accumulation of aircraft in the sky (or on the
ground) when one does circuits? When I do them, the number of takeoffs
does in fact equal the number of landings. I just do more of them.

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain." (chapter 10 of book 3 - Harry Potter).
for Email, make the obvious change in the address.