yes, sorry
getPos returns the position of the object, in this case the chopper. The position is an array - obviously you need an x coordinate, a y coordinate and a z coordinate. What you need to do is extract the height coordinate. So what I was really saying
? 25 < chopper height < 40:trigger1=1
I'm a bit vague on how to extract a particular coordinate, I thought that was right. this select 0 is N-S and this select 1 E-W. Of the other way around.
Look up getpos in the command ref .... also read the section on arrays. You'll need to make sure whether you're talking about absolute height or height above the ground at that place.
Hopefully somebody who actually knows about arrays will be along soon ;D
edit: you see, LCD is here already