Mavic Pro flew away following erratic flying, loss of control

[JNU]

Yesterday I took my Mavic Pro on a routine flight, with a fully charged battery and a normal default RTH height of 98 ft, flying in normal mode (not sport) for the entire flight. It was 0 degrees C at the time...I fear this could be the root of all the problems I then experienced.

4 minutes into the flight, with 81% battery and at a height of 250 ft, I hit return to home.

Something very strange then happened.

The sequence of events that followed immediatley after were:

1. In RTH mode, Mavic started to climb, without any input from me.
2. I tried to counter this by pulling down on the altitude stick briefly, log shows me pulling down on stick 20%-60% for around 2 seconds. This cancelled the RTH.
3. The Mavic didn't respond and rapidly continued to climb and was also now flying away from me, backwards, with no input from me on the remote control.
4. The Mavic climbed to 311 ft on its own, and I again hit RTH, and it went into RTH mode.
5. The Mavic continued to climb with no input from me, and continued to rapidly fly further away in a straght line ascending upwards, and making big distance gains away from me.
6. I again tried to counter this by pushing the forward stick 100% on the RC, for 15 seconds. This did nothing, and the Mavic continued to fly away backwards in a straght line at around 12mph and rapidly climbing without any command, was now up to 370 ft and climbing.
7. I again hit RTH, and it went back into RTH mode.
8. In RTH mode and with no input from me on the RC, it continued to rapidly climb through 400 ft, and continuing to fly away from me backwards, totally out of control and getting further and further away.
9. Climbing through 403 ft, speeding away from me, "Battery:Overcurrent during discharge" warning was displayed. Never experienced this before.
10. Still with no input from me on the RC whatsoever, Mavic continued to fly away in a straght line, climbing, now at 420 ft and distance by this point becoming a real concern (had now reached 7,700 ft away from me, still out of control)
11. This continued a few more seconds and at a height now of 430 ft, I recieved "Motor Current Error" warning, also never experienced before. Battery at this exact moment showed 54% remaining and 4 min 30 sec remaining on the countdown bar.
12. At a height of 440 ft and climbing, and a somewhat terrifying 7900 ft away, it disconnected, and never reconnected.

This all happened over a golf course. It was unoccupied at the time, due to being covered in snow. I immediatley got in the car and drove to the area, and pulled up Find My Drone on my iPhone. On foot, I went to the exact point shown on the map, which was in the middle of a green area. No sign of the mavic anywhere.

I then spent the next 2 hours searching the area, without being able to find it. Today, I went back with two others and we searched the area extensivley again for a further 3 hours, and nothing. We tried to simulate the drone flying further away in a straght line, searching the area but no sign of it. I guess this suggests the flight continued for some time on its own accord following disconnect and went further away. There are woods either side of the area, so likely it could be in there somewhere and that is literally like trying to find a needle in a haystack.

I will try and upload the flight logs, but upon first glance has anybody ever experienced this complete loss of control and does anybody have any idea as to why this may have happened?

I will contact DJI care about this, and will update this thread with their response when I get it. I'm looking at a claim on my home insurance for this, but in the meantime would love to hear if anyone has experienced similar issues as this was pretty scary, and has sadly resulted in a complete loss.

Thanks all in advance
Justin

 

[Bunny Too]

Yesterday I took my Mavic Pro on a routine flight, with a fully charged battery and a normal default RTH height of 98 ft, flying in normal mode (not sport) for the entire flight. It was 0 degrees C at the time...I fear this could be the root of all the problems I then experienced.

4 minutes into the flight, with 81% battery and at a height of 250 ft, I hit return to home.

Something very strange then happened.

The sequence of events that followed immediatley after were:

1. In RTH mode, Mavic started to climb, without any input from me.
2. I tried to counter this by pulling down on the altitude stick briefly, log shows me pulling down on stick 20%-60% for around 2 seconds. This cancelled the RTH.
3. The Mavic didn't respond and rapidly continued to climb and was also now flying away from me, backwards, with no input from me on the remote control.
4. The Mavic climbed to 311 ft on its own, and I again hit RTH, and it went into RTH mode.
5. The Mavic continued to climb with no input from me, and continued to rapidly fly further away in a straght line ascending upwards, and making big distance gains away from me.
6. I again tried to counter this by pushing the forward stick 100% on the RC, for 15 seconds. This did nothing, and the Mavic continued to fly away backwards in a straght line at around 12mph and rapidly climbing without any command, was now up to 370 ft and climbing.
7. I again hit RTH, and it went back into RTH mode.
8. It continued to rapidly climb through 400 ft, and continuing to fly away from me backwards, totally out of control and getting further and further away.
9. Climbing through 403 ft, speeding away from me, "Battery:Overcurrent during discharge" warning was displayed. Never experienced this before.
10. The Mavic continued to fly away in a straght line, climbing, now at 420 ft and distance by this point becoming a real concern (had now reached 7,700 ft away from me, still out of control)
11. This continued a few more seconds and at a height now of 430 ft, I recieved "Motor Current Error" warning, also never experienced before. Battery at this exact moment showed 54% remaining and 4 min 30 sec remaining on the countdown bar.
12. At a height of 440 ft and climbing, and a somewhat terrifying 7900 ft away, it disconnected, and never reconnected.

This all happened over a golf course. It was unoccupied at the time, due to being covered in snow. I immediatley got in the car and drove to the area, and pulled up Find My Drone on my iPhone. On foot, I went to the exact point shown on the map, which was in the middle of a green area. No sign of the mavic anywhere.

I then spent the next 2 hours searching the area, without being able to find it. Today, I went back with two others and we searched the area extensivley again for a further 3 hours, and nothing. We tried to simulate the drone flying further away in a straght line, searching the area but no sign of it. I guess this suggests the flight continued for some time on its own accord following disconnect and went further away. There are woods either side of the area, so likely it could be in there somewhere and that is literally like trying to find a needle in a haystack.

I will try and upload the flight logs, but upon first glance has anybody ever experienced this complete loss of control and does anybody have any idea as to why this may have happened?

I will contact DJI care about this, and will update this thread with their response when I get it. I'm looking at a claim on my home insurance for this, but in the meantime would love to hear if anyone has experienced similar issues as this was pretty scary, and has sadly resulted in a complete loss.

Thanks all in advance
Justin

I am so sorry to hear of your loss @JNU, that is a major drag; I hope this has a happy ending.

 

[sar104]

We need the .txt log to make any useful comments on this.

 

[JNU]

We need the .txt log to make any useful comments on this.

On it now. What is the best way to get this uploaded? Thanks a million.

 

[BD0G]

The DAT flight logs are stored internally on your Mavic. The TXT flight logs are stored on the mobile device running DJI GO. You can find tools to retrieve/read those flight logs here.

Just copied this and pasted from @Msingers valuable information that he provides.

After posting the flight logs it is much easier to have others on the forum examine what happened and where to approximate where the Mavic's final resting spot is. (that sounds kinda morbid , but applicable)

 

[JNU]

The DAT flight logs are stored internally on your Mavic. The TXT flight logs are stored on the mobile device running DJI GO. You can find tools to retrieve/read those flight logs here.

Just copied this and pasted from @Msingers valuable information that he provides.

After posting the flight logs it is much easier to have others on the forum examine what happened and where to approximate where the Mavic's final resting spot is. (that sounds kinda morbid , but applicable)

Thanks - I've just saved the .txt file from my iPhone using iTunes to my PC.

 

[JNU]

We need the .txt log to make any useful comments on this.

Thanks a million. Here we go:

 

[sar104]

Thanks a million. Here we go:

Well that's a sorry tale. Firstly, take a look at the wind speeds. Up to 40 mph blowing the aircraft away from you. And there were 8 high wind warning notifications.

If you look at the telemetry, the aircraft simply could not hold against that wind. It tried, and ended up with motor overcurrent errors, and simply blew off downwind, eventually losing connection. I'm afraid that was completely self-inflicted.

 

[JNU]

Well that's a sorry tale. Firstly, take a look at the wind speeds. Up to 40 mph blowing the aircraft away from you. And there were 8 high wind warning notifications.

If you look at the telemetry, the aircraft simply could not hold against that wind. It tried, and ended up with motor overcurrent errors, and simply blew off downwind, eventually losing connection. I'm afraid that was completely self-inflicted.

View attachment 32667

Thanks a lot for reviewing the telemetry and so quickly. Can clearly see the wind was the issue there and it took over. It was calm when I took off but clearly there were some horrible gusts soon after and RTH didn’t work in time as it was already caught up. A lesson learned and one I will have to live with.

I am going out searching again tomorrow and will update thread if I find it. Appreciate the analysis, thanks again.

 

[sar104]

Thanks a lot for reviewing the telemetry and so quickly. Can clearly see the wind was the issue there and it took over. It was calm when I took off but clearly there were some horrible gusts soon after and RTH didn’t work in time as it was already caught up. A lesson learned and one I will have to live with.

I am going out searching again tomorrow and will update thread if I find it. Appreciate the analysis, thanks again.

This may be somewhat inaccurate with those winds, but you might be able to narrow down your search area. After losing connection it will have stayed in RTH mode and continued to drift until it reached critical battery autoland. Extrapolating power drain rate gives the following distance estimate:



That suggests it may have auto landed in the region of 3700 m from the home point. That gives the following estimated location, at the intersection of the line and the circle:

 

[msinger]

It's going to be tough to pinpoint the landing spot since the wind speed didn't seem to be too consistent. According to my calculations, I'd recommend you start looking for it in this yellow box.

 

[dpeagle]

boy can you imagine the wind chill factor if ground level was 0 c and you were that high up with 40mph winds.

 

[rfc]

Well that's a sorry tale. Firstly, take a look at the wind speeds. Up to 40 mph blowing the aircraft away from you. And there were 8 high wind warning notifications.

If you look at the telemetry, the aircraft simply could not hold against that wind. It tried, and ended up with motor overcurrent errors, and simply blew off downwind, eventually losing connection. I'm afraid that was completely self-inflicted.

View attachment 32667

Downwind travel would be expected, but what caused the apparent insistence of the bird to keep climbing? Have to rule out a thermal, lol.

 

[sar104]

Downwind travel would be expected, but what caused the apparent insistence of the bird to keep climbing? Have to rule out a thermal, lol.

That is a bit strange, but if you look at the calculated wind speed as a function of altitude it is somewhat suggestive of unsteady flow and perhaps thermals:

 

[rfc]

This is still bothering me. In dead calm, the A/C pitches forward to make forward speed towards the desired location (home point in this case). There's a limit to the pitch in software. So, is it possible that if the winds increase beyond a certain point, if the A/C is at max pitch, the only way to maximize forward speed is to increase throttle, so it does so.
As a result, it gains altitude (that takes a "back seat" in the software to progress towards the home point).

I can't see in the data that this necessarily works...there are a couple of pulses showing home point distance decreasing briefly during ascent, but nothing that produces an "ah ha!" moment. Could this just be a quirk in the software?

 

[sar104]

This is still bothering me. In dead calm, the A/C pitches forward to make forward speed towards the desired location (home point in this case). There's a limit to the pitch in software. So, is it possible that if the winds increase beyond a certain point, if the A/C is at max pitch, the only way to maximize forward speed is to increase throttle, so it does so.
As a result, it gains altitude (that takes a "back seat" in the software to progress towards the home point).

I can't see in the data that this necessarily works...there are a couple of pulses showing home point distance decreasing briefly during ascent, but nothing that produces an "ah ha!" moment. Could this just be a quirk in the software?

The firmware limits airspeed, not ground speed via pitch. Ground speed may be separately constrained in GPS flight.

 

[JNU]

This may be somewhat inaccurate with those winds, but you might be able to narrow down your search area. After losing connection it will have stayed in RTH mode and continued to drift until it reached critical battery autoland. Extrapolating power drain rate gives the following distance estimate:

View attachment 32675

That suggests it may have auto landed in the region of 3700 m from the home point. That gives the following estimated location, at the intersection of the line and the circle:

View attachment 32676

UPDATE

Well sar104, I am amazed. I cannot thank you enough for your prediction, as I went to this area this morning and your estimate was absolutley spot on! I walked to the exact area you suggesed at the intersection of the plotted lines and started searching, and found it at the point shown above. Your calculation was entirley correct. Thank you so much!

In terms of the drone, it was upright in the grass, intact and the only visible damage I can see is a small crack to one of the rotors, no other visible damage, just very damp. Memory card and footage also intact, I watched the footage and, as you predicted, it was drifting further and further away in the wind, for a full 15 minutes after the disconnect.

It then descended, with a lot of movement left to right as it got lower down, and completed what looks to be a very hard landing, onto snow covered grass. Was then burried in the snow for 48 hours.

It narowly missed trees and a river, by a matter of a few feet either side. I am not sure how well it was working on avoiding these at the point of critical battery landing or whether this was simply luck, but I was amazed to have found it - was truly like looking for a needle in a haystack.

My next steps now are to dry it out thoroughly and then carefully test it. I will update the thread this week with the outcome.

Really wasn't expecting to find it after 3 days searching, so thanks again for the advice, a great result today.

 

[JNU]

It's going to be tough to pinpoint the landing spot since the wind speed didn't seem to be too consistent. According to my calculations, I'd recommend you start looking for it in this yellow box.

View attachment 32731

Thanks also for this - this was extremely close to where it landed.

 

[sar104]

UPDATE

Well sar104, I am amazed. I cannot thank you enough for your prediction, as I went to this area this morning and your estimate was absolutley spot on! I walked to the exact area you suggesed at the intersection of the plotted lines and started searching, and found it at the point shown above. Your calculation was entirley correct. Thank you so much!

In terms of the drone, it was upright in the grass, intact and the only visible damage I can see is a small crack to one of the rotors, no other visible damage, just very damp. Memory card and footage also intact, I watched the footage and, as you predicted, it was drifting further and further away in the wind, for a full 15 minutes after the disconnect.

It then descended, with a lot of movement left to right as it got lower down, and completed what looks to be a very hard landing, onto snow covered grass. Was then burried in the snow for 48 hours.

It narowly missed trees and a river, by a matter of a few feet either side. I am not sure how well it was working on avoiding these at the point of critical battery landing or whether this was simply luck, but I was amazed to have found it - was truly like looking for a needle in a haystack.

My next steps now are to dry it out thoroughly and then carefully test it. I will update the thread this week with the outcome.

Really wasn't expecting to find it after 3 days searching, so thanks again for the advice, a great result today.

I'm glad to hear that you found it. With the unusual wind pattern there was a significant element of luck in the predicted location being that close, but sometimes competing uncertainties cancel out. There should be a good chance that it will be fine once it dries out, although I'd be a bit careful with the battery if it got very wet.

I'd be interested to see the video and the onboard DAT file if you have the energy to try to extract and post it, just to figure out exactly why it was climbing. The latest Mavic firmware seems to have caused some problems getting the DATs, but the instructions that used to work are here:

How to retrieve a V3 .DAT File from the AC

 

[BD0G]

I knew that when @sar104 and @msinger joined the thread that this was going to turn out well and give you a fighting chance of finding your Mavic!

When these guys (and BudWalker) join forces the potential to find ones lost Mavic goes up exponentially!

They are perfecting the art of proper interpretation of the data that the flight log files provide. Its not an exact science , but time and time again there are positive results.

Might I suggest investing the 5 bucks a month in a StateFarm Personal Articles Policy that covers just your Mavic and will cover cases such as this. I spend more than that on a cup of foo-foo coffee daily and it gives piece of mind. You do not need to have anything else insured with them to have a policy provided.

If you go the tracker route and buy a trackimo or similar tracker I will 3 D print you a mount for your Mavic at no cost (as I cant sell parts on the forum , but I sure can give them away.