Today I went through a problem that had never happened before.
I made a mission with points of passage to test the range of my telemetry, the plane did everything right, took off, arrived at the correct altitude until the WAYPOINT 6, after, it began to lose altitude continuously until falling in a tree.
All instruments showed a decrease in acceleration and a decrease in altitude correctly, there was no error in the altitude of the barometer or GPS. It seemed that WAYPOINT 7 really should pass at 0 meters of Altitude. The system even turned the engine off and gently lowered the altitude.
Actually, I was out of action, I should have assumed the flight, finally, when I realized I was well below the expected height I was afraid to change the flight mode, because it was very low.
Firmware version is 3.9.3 Arduplane, I am using a PIXHAWK 2.4.8 with Airspeed installed, GPS M8M and other GPS RTK EMLID, was in RTK FIXED mode.
Follow Flight Log and Mission File.