I thought my problem was that I did not use a proper rangefinder. I wonder if I could create a virtual rangefinder like you answered in this topic.
Precision Landing: receiving Mavlink Messages but drone is not taking orders - ArduCopter / Copter 4.1 - ArduPilot Discourse
Can you give me any ideas to create the virtual rangefinder and how to use this with Landing_Target message? Thank you in advance.