What is the best way to set the altitude of a landing area that is at a significantly different altitude than your home point/ take off point?
I would prefer not to use absolute altitude for the entire flight, or terrain following as I want the plane to preform as normal above home altitude for the entire flight, except, for the landing sequence.
Also, if you do use absolute altitude, how do you properly figure out the absolute altitude at a different location so that it matches what the autopilot will estimate when it comes in for landing?
We are planning to do a long range test of an airplane and the landing point will be a few thousand feet lower in altitude than the take off point in the mountains.
Just use a value different than zero as an altitude parameter in the flight plan’s LAND command. If your runway is 300m lower than HOME, then enter -300 for the LAND altitude. Do the same for each WP altitude in the approach path that should be relative to the runway.
Absolute Altitude is tricky for auto landings. I try not to mix the two but it is doable. The auto pilot is going to use whatever offset MP told it to use. MP uses SRTM data which can be off quite a bit. Ideally you would aquire an accurate elevation for the intended runway, compare that to MP’s elevation for that area, then apply the difference as the LAND altitude parameter.
I think if I use a LIDAR and use the estimation of altitude difference it should work out ok as once the LIDAR kicks in, it will adjust for the errors. For this plane I will probably use a Lidar with 100 meters of range so it has more time to adjust.
But, Actually, you need to think about QNH between the two spaces, that will interfere the barometer.
LIDAR is good for the approach and flare phase for landing