A while ago I did the first flight of my new (and first ever) drone. And I ran into a problem that puzzles me. I prepared everything as best I could: Fully charged drone battery, fresh alkaline transmitter batteries, I calibrated the sensors (gyros/accelerometers, and compass) according to the procedures outlined in the manual, watching for the proper light flashing codes, then confirmed (also by the drone lights) that the GPS had locked in and was ready to fly. Then I took off, using the automatic takeoff function. The drone took off fine - but kept climbing slowly, and drifting sidewards, slowly too. I could easily compensate for that with the sticks, but I had expected a GPS drone to be more stable than that. It drifted sidewards, front and back, up and down, as if the slight breeze with its turbulence was affecting it, and I couldn't see nor hear any automatic action to counteract this drifting. Anyway I flew about 20 meters forward, then back, noticing that it went forward far easier than back. Also I tried some sideward flying, this too had a bias, going much faster to one side than the other. I didn't try trimming it at that time, since the drifts were easy to compensate for. Then I rotated the drone over is axis, that went fine. Then I flew an extended circle, by giving it a constant forward speed and controlling its heading. Several times during this I had to correct the altitude, because it kept drifting up and down, but mostly up. And then, suddenly it stopped responding to control input! It kept hoovering, drifting up and sideways, and there was ABSOLUTELY no reaction to anything I did! After noticing that it didn't react to the sticks anymore, I pressed the return-to-home button, to no effect, and then the automatic landing button, to no effect either. I could do nothing but watch the drone climb slowly and drift away ever faster, out of the field and toward a forested hill. I ran after it, trying not to lose sight, repeatedly trying to activate the return function, and trying to get any control by the sticks - no reaction. Finally - and fortunately - it had an encounter with a treetop at that forested hill, and fell about 30 meters down through the tree. The ground of that forest section is thickly covered in blackberry and other thorny plants, so I had to get the machete I had in my car for precisely such needs, and hack my way to the place where the drone was. At first I couldn't see it, but by repeatedly arming and disarming the motors via the remote control and listening for the prop sound I finally found it, hanging low in the tree with one prop blocked by a twig. The good news: It suffered absolutely no damage. The bad news, of course: It's useless if it loves to just fly away! As you surely noticed, the control was working fine after the crash, allowing me to arm and disarm the motors. And at the time it stopped working in mid flight, the drone was at most 30m away from me. After retrieving the drone I did a range test on the ground, by arming/disarming the motors several times while walking away, and I had solid control up to a distance where I could barely see the drone, easily 100 meters. So it clearly wasn't a range problem. Now I need your help to try finding out what happened. I see some possibilities, but since I have no experience with drones, nor with 2.4GHz remote controls, I need help. I do have experience with "antique" 72MHz remote controls, because I used to fly model aircraft in the past, in the days of glow plug engines and digital proportional FM remote controls. I can't remember any case of any of my Futaba radio controls stopping to work in mid flight. My ideas, subject to your judging: - Could it be that since the drone was set to slow (beginners) mode, it just didn't have enough speed available to compensate for wind? Does that speed limit act before or after position control? I mean, is the limit a net limit, by GPS, or a gross limit in the differential motor speed? - Could it be that the drone drifted out of an "electronic fence", and instead of returning into it, stopped reacting? That would be a software bug, of course. - Or could it be that the GPS signal was poor, and the GPS position reference drifted, so that the electronically fenced area moved away? But even then it should have returned to whatever it thought was its takeoff point! - Could it be that the drone self-interfered in some way, for example by brush noise from its motors? When it loses the control signal it should return home automatically, which it did not. So the interference would have needed to be so bad that the GPS too lost its signals. External interference is almost impossible, because the location is far away from any interference source. Like 400 meters from the nearest power line, and 600 meters from the nearest house, which happens to be mine, at everything was off at home. The nearest neighbor lives more than a kilometer from that place. The place where it first lost control was significantly closer than the fartherst place I flew it while it still worked. The whole flight might have lasted for 2 minutes, and probably less. I don't know what to do now. If I take off again and it flies away again, there might be no kind tree in its path to catch it for me.