endotherm
 First Officer
Flight distance : 503241 ft
Australia
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DavidRBrown Posted at 7-2 11:01
At the point of failure the compass goes haywire, but the strange thing is I'm a mile from anywhere in the middle of fields -just doesnt make sense.
Just from looking at the Phantom Help site results, I can see that at 4min 45.8sec your aircraft took a sudden tilt to the right and started into a tumble -- we see the airspeed pick up while the altitude decreases. As such, it only took a couple of seconds to impact with the ground and telemetry stopped. The tumble, across each axis, would account for a changed orientation to the sky and would explain the number of GPS satellites rapidly changing. This is physics, not a fault. The compass going "haywire" is a result of accurate readings during the tumble, not a cause of it. A compass error is not catastrophic, normal flight can continue successfully if there is a momentary glitch or disturbance. It usually means there is a disagreement between other positional sensors and the compass sub-system. DJI software merely returns "compass error" as a generic fault message in this instance instead of pages of incomprehensible data. These compass errors generally correct themselves moments later unless there is physical damage or a catastrophic event. The magnetic field interference error only appears when the aircraft has hit the ground. Again, not the cause of the failure. Exiting P-GPS occurs when the satellite data is unreliable, the system switches to ATTI to allow you to continue flying manually. It switches back to GPS mode when GPS signal is reliable once again, generally moments later. Your low radio signal is probably the result of having the legs (containing the antenna) point away from you when it was tumbling, providing you with an obstructed transmission.
None of these things is a fault, they may be commonly reported but they have a logical explanation. They are usually not catastrophic in nature either and don't constitute a "design fault" or similar, as some people like to claim. The "self-tightening props" just means that by spinning your motors faster than the momentum of the prop blades, they will tend to work their way tighter into the threaded hub. It does not forgive you if they weren't attached sufficiently tight in the first place, or if the hubs were damaged or worn. Varying acceleration and braking can overcome a weakly applied prop, and the prop's momentum can slowly work its way off, leading to a lost prop and a crash as you saw. Not saying that applies in your case (I've not seen any evidence yet), but be aware. It's important to find out, were all 4 props attached to their motors when the aircraft was recovered?
At this point we don't know what caused your aircraft to flip. I'll have a look at the full flight record when time permits and see if something jumps out at me.
P.S. I can see that you were flying very sedately prior to the incident. There is just a sudden catstrophic failure. As to the cause, it is anybody's guess. Usual suspects = birdstrike, loss of prop (improperly tightened/cross-threaded/stripped hub), failure of motor/ESC, physical damage to wiring etc. Regarding the magnetic anomaly, is there possibly a burried pipe or similar between the plowed field and road or the wire fence?
Also, it would appear your battery was ejected upon impact, which would immediately stop telemetry (as we see) and recording of video. This is supported by the fact your recording was corrupt. Inserting the card into the camera and re-powering it up again usually finishes the write properly and repairs the corruption.
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