Yeah, surprising as this may sound, helicopters can't just stop in mid-air on a whim.
Flyinheight only goes down to 30m, but at this height and at a slow speed ( set it to Careless as well ) you should be able to do it with ain invisible H.
Oh and trust me, you really don't want a 'land' type command, as then you have to stop the waypoints to get it to fly off again.
Even a 'land get in' command can be risky, try having them get into it, with a 'get in' command syncronised to the waypoint afterwards, NOT the same waypoint as you would like it to land. Then it will work properly.
Have fun!