_myHeight = _this select 0
_plane = "Plane" createVehicle getMarkerPos "Mkr_Plane"
_plane setPos [getPos _plane select 0,getPos _plane select 1,(getPos _plane select 2) + _myHeight]
_man = "Man" createUnit [getMarkerPos "Mkr_Plane",groupMan,"man1=this; this moveInDriver _plane",0.5"PRIVATE"]
_man doMove getPos myLogic
That should work. Make that as a script and execute the script as such:
[HeightPlaneIsToFlyIn] exec "scriptname.sqs"