I’m not sure where this post belongs, so I will start here.
Situation: I was flying a F550 hexacopter with Pixhawk 1 running PX4 v1.8.2. It was checked out on the bench for all flight modes and everything was working. When I went outside to fly it, I checked out all functionality on QGroundControl, and watched the screen as I switched between all flight modes and they all appeared on the screen. GPS had 20 satellites. The Pixhawk light was green. Everything appeared to be good. I powered up, armed it in MANUAL mode, and I made a short flight to confirm everything was airworthy.
On the ground, I put it in ALTITUDE mode, took off and let it hover at 20 meters. Then I switched to POSITION mode. Instead of hovering in place, it started to move away from me and started climbing. Immediately I changed to MANUAL mode and tried to regain control. Nothing happened. Changed to STABILIZED mode. No help. Tried ALTITUDE mode. Nothing. Then I hit the RTL switch. No response. It kept moving steadily away. Then I tried all the flight modes many times but there was absolutely no response from the drone. I watched helplessly as it went out of sight. I watched the path on QGC. It was traveling towards a highway and a highly populated area, so I put the throttle in max position hoping that would keep it high. Altitude eventually went to 800 meters, yet nothing I did with RC control did anything to get it to come back.
Eventually I lost telemetry and data stopped. It was then at about 120 meters and coming down slowly, and the battery was very low so I knew it would be on the ground soon. The last known position was noted and we went to the area to look for the drone. This is a heavily wooded area, and after looking for it for a few hours, we have not found it, and may never get it back. Hence no log files are available.
One thing I remembered from the pre-flight checks was that I could not arm the drone in POSITION mode, but I thought that was not allowed, so I ignored it. In retrospect , maybe that indicated a problem.
Can anyone offer any ideas as to why this drone ignored MANUAL RC control?