Help...Mavic went haywire and ignored my controller, crashing somewhere out of reach

[sar104]

Thanks for the detailed reply!
Sorry if I'm a bit thick, but I don't quite follow. Let me see...There's a full forward very short altogether with full left panning for a while, so I initiate a panning move (1m02 in the app). I follow this by short rotations to the right so it keeps us in frame as it moves. Then at 1m10s I do a full forward for about 2 seconds, intending to stop the panning. From there, it starts moving forward, catching speed. I do a couple of tentative braking (full lever, but very short periods). After I notice there's no effect and the drone keeps catching speed, I go full backwards at 1m16, and I keep it that way until it crashes at 1m21. It had nearly 5 seconds to brake at full power backwards, and yet it kept catching speed.

Whenever I did braking maneuvers before, from full speed, it usually took a full second in getting to a complete halt. During that time, the distance covered is still long, which is a different thing, but it usually brakes to a halt in about a second. It had nearly 5 seconds to brake, and when it crashed it was still accelerating. The final aileron movement right before the crash was a final useless desperate attempt to get it to change course...but too little too late.
Can you explain how I did wrong? I mean, if I knew something was up earlier, I might have pushed back the lever 4 seconds earlier...but I still feel the drone ignored the input after 1m10s, and specially after I start pushing backwards full time.

I'm sorry - all I can do is refer you again to the the data that I posted above (#13) which shows that the aircraft responded correctly, in terms of pitch and roll, to your stick inputs. In ATTI mode that is all that the aircraft does in terms of horizontal motion; it translates elevator and aileron to pitch and roll. The actual resulting motion is the result of those attitude changes plus existing velocity plus local wind speeds.

 

[BudWalker]

......... After I notice there's no effect and the drone keeps catching speed, I go full backwards at 1m16, and I keep it that way until it crashes at 1m21. It had nearly 5 seconds to brake at full power backwards, and yet it kept catching speed.
.

At 77.834 secs the elevator was released briefly. This resulted in a pitch down. Shortly after the elevator went full back again the throttle was pulled all the way back. I suspect that it was the addition of full negative throttle that prevented the desired return to pitch up. It's hard to know exactly what the response will be when multiple inputs are changed like this.

 

[sar104]

At 77.834 secs the elevator was released briefly. This resulted in a pitch down. Shortly after the elevator went full back again the throttle was pulled all the way back. I suspect that it was the addition of full negative throttle that prevented the desired return to pitch up. It's hard to know exactly what the response will be when multiple inputs are changed like this.
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I agree that's likely what is happening after 78 s, at which point there was also full left rudder applied. Since first impact with the vegetation was at 79.3 it was a done deal by then.

 

[f3honda4me]

Full down elevator when combined with full throttle down will not slow the forward momentum of the drone. If you had only applied full elevator down and left throttle at center or even increased it, you probably would have stopped the drone from crashing.

Good information as always sar and bud.

 

[msinger]

If you had only applied full elevator down and left throttle at center or even increased it, you probably would have stopped the drone from crashing.

... or throttle up to clear the trees.

 

[pixl]

Full down elevator when combined with full throttle down will not slow the forward momentum of the drone. If you had only applied full elevator down and left throttle at center or even increased it, you probably would have stopped the drone from crashing.

Good information as always sar and bud.

The OP is taking it well and owning up to the errors. Pretty refreshing stance IMO.

 

[msinger]

The OP is taking it well and owning up to the errors. Pretty refreshing stance IMO.

I don't think he's quite on board yet. Check out his last post here.

 

[pixl]

I don't think he's quite on board yet. Check out his last post here.

Oops, I mixed him up with the fellow in Hong Kong

 

[timonoj]

Lol...I am A Fellow in Hong Kong. But not sure if the one you were referring to. Yeah, I now understand what you guys meant, with the braking while descending, then stopping braking and starting again... Thanks for the kind help carefully explaining the logs for me. I'll update a bit this post...
After some back and forth with DJI, their explanation was way crappier, but I now understand them rejecting my claim. They gave me the classic 15% discount and by now I already have a new Mavic. Being in HK, the thing was ordered on a Friday morning and delivered the next day. My next destination is Vietnam for Christmas, hopefully this time I'll just have cool videos and no sad crash tales

 

[pixl]

Lol...I am A Fellow in Hong Kong. But not sure if the one you were referring to. Yeah, I now understand what you guys meant, with the braking while descending, then stopping braking and starting again... Thanks for the kind help carefully explaining the logs for me. I'll update a bit this post...
After some back and forth with DJI, their explanation was way crappier, but I now understand them rejecting my claim. They gave me the classic 15% discount and by now I already have a new Mavic. Being in HK, the thing was ordered on a Friday morning and delivered the next day. My next destination is Vietnam for Christmas, hopefully this time I'll just have cool videos and no sad crash tales

If you're heading to Vietnam, beware of the Danang Airport if you're flying there direct from an international destination -- they've been seizing drones there. Hanoi and HCMC are fine, last I heard.

 

[timonoj]

WTF. I'll need to check. Do you have any specific links?

 

[stressor]

Wow...I'm impressed with the level of detail you pulled. Thanks. Screw it, since DJI didn't reply in the last 24h I'll upload the video. Give me a few minutes.

Here it is:

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The levers reaction is a bit out of sync for the first 30 seconds (that's the app recording at a different framerate), but in the important section when it starts misbehaving, it's on sync.

Please let me know your thoughts.

Let me say I feel your pain 100%, but on the other hand from the video, flying in a mountainous area, without GPS lock, whilst walking on a narrow fixed path/ledge to my eyes is recipe for disaster. Better would be to have a second person in a fixed location close to you fly (in short bursts, and give 100% concentration on it). Not to mention landing (?or emergency landing) looks like it might be a problem around there. I am not preaching, fly wherever you wish, I am just saying I would say this was a high risk situation regardless of the drone behaviour. Best of luck with the new drone.

 

[FASTFJR]

From the looks of the crash it seems to be 15ft-20ft above the pathway. Ge some rope and start climbing!

 

[SprayingMango]

Oh look...once again user error and NOT device failure. Refreshing.

 

[OzoneVibe]

Oh look...once again user error and NOT device failure. Refreshing.

Really? When there is quite obviously zero response from the full back input on the right stick?

 

[sar104]

Really? When there is quite obviously zero response from the full back input on the right stick?

That's not really correct. This was in ATTI mode, and the pitch/roll response of the aircraft was appropriate to the stick inputs. See post #13 for the details.

 

[OzoneVibe]

That's not really correct. This was in ATTI mode, and the pitch/roll response of the aircraft was appropriate to the stick inputs. See post #13 for the details.

That shows you stick positions.
Most important in the video in post #13 is that at 45secs there us full back input with absolutely no change in attitude in the MP.
Like I said. Zero "response" .... irrespective of input from that point on.

 

[sar104]

That shows you stick positions.
Most important in the video in post #13 is that at 45secs there us full back input with absolutely no change in attitude in the MP.
Like I said. Zero "response" .... irrespective of input from that point on.

You cannot determine aircraft attitude from the video - that is only apparent in the pitch/roll data. Your comment "zero response" is absolutely incorrect.

 

[OzoneVibe]

You cannot determine aircraft attitude from the video - that is only apparent in the pitch/roll data. Your comment "zero response" is absolutely incorrect.

I make that assessment from the stick being fully back at that point in the video and there being no change in acceleration toward it's final destiny.
That much stick back, in the time it had, would have slowed, if not stopped, the MP? Takes no time.

 

[CyberdyneSystems]

I thinks a combination of full back on the right stick while also asking for minimum throttle. Your not giving the craft much power to effect its direction of travel and that's why it appears to not be responding.