And two months later... Sorry, I forgot to check for responses :) And no worries - up to you. My reason for posting this is because leaving the Chopper without landing reveals the trick of its flight - that is to say, it's not actually flying, but simply casting an offset shadow. Of course, being able to interact with structures from the chopper does the same thing, so oh well.
I guess I was just surprised that my Chopper apparently auto-rotated into a lake :)