Please take a moment and update your account profile. If you have an updated account profile with basic information on why you are on Air Warriors it will help other people respond to your posts. How do you update your profile you ask?
Thought the same thing. Maybe if they know the slope angle, and he goes in " level " he knows they have X feet of clearance. I have no experience with helicopters other than riding in them, but I'm guessing that is much harder than he made it look.