I lost my Mavic and need help finding out what happened - FOUND BY STARZ!

[Pablo]

I'll keep this as brief as I can.

What happened: I lost my Mavic behind a huge rock in the middle of the Arizona desert. I was doing a POI around the rock, the battery dropped just below 30%. I cancelled the POI, took control, gained altitude to avoid the rock, pointed the Mavic back to me. Then as I was about to return it home it took over and, without warning, descended quickly behind the rock. I lost connection and return to home didn't work. It was such a dangerous location that I was unable to go and retrieve the Mavic. It's gone. I tried my best to get it but had to leave it behind. Devastated.

The aftermath: As I've lost the Mavic I can't access the full log files. When I try to view the flight in the DJI GO 4 app it crashes every time I click the flight icon. I suspect the flight record is corrupt. As it stands I have no way to review the flight and figure out what happened. Can anyone help?

 

[Pablo]

The video of the flight from my phone for reference (excuse the poor quality):

1. I get a battery 30% warning and cancel POI on 13 seconds and take control.
2. On 59 seconds I have positioned it above the rock, facing back to my location.
3. I start to head home, then on 1min 5 seconds it just auto-descends behind the rock and it's gone.

 

[halley]

Sounds like low-battery emergency landing. And it looks like it's in the middle of the top-most craggy rocks of that peak. Get your hiking boots, it does not look like you would need technical climbing gear to go up there.

 

[Pablo]

Sounds like low-battery emergency landing. And it looks like it's in the middle of the top-most craggy rocks of that peak. Get your hiking boots, it does not look like you would need technical climbing gear to go up there.

I was on holiday there. I'm back in England now. It's fair to say retrieving it now is not an option!

Anyway I was inappropriately dressed to go and get it. It wasn't so much the rock I was scared of scaling (although it was far bigger than it looks in the video). It was way out in the middle of the Arizona desert, behind barbed wire fences, about 200m, through pretty thick grass. I know how many dangerous things are out there. I was all alone. I didn't see another soul the whole time I was out there. If I had goten bitten etc. I would have been in big trouble. No one knew I was out there. It was a sickener deciding not to try and retrieve it, but I think it was the only sensible call. If anyone wants to go get it for me I'll happily give them the location!

Mainly I just want to figure out what happened. I also suspect it auto-landed but without reviewing the flight I can't see what the critical low battery was set to (what is the default?). If it did auto-land it must have been at about 25-30% at the time, and I didnt see a warning.

 

[mbuk]

Gutted for you!

Just out of interest:

Rough distance from your location to the Mavic?

What phone were you using?

What version of DJI Go?

What setting did you have for Remote Control Signal loss in App? (Hover / Land / RTH)

If I remember correctly if it was a critical battery landing you should have been able to maintain a hover by pushing the stick up to then manoeuvre to a better landing spot. But I guess it relies on you have a signal and reacting quickly.


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[Pablo]

Gutted for you!

Just out of interest:

Rough distance from your location to the Mavic? About 300-400m

What phone were you using? S7 Edge

What version of DJI Go? DJI Go 4 (latest)

What setting did you have for Remote Control Signal loss in App? (Hover / Land / RTH) RTH

If I remember correctly if it was a critical battery landing you should have been able to maintain a hover by pushing the stick up to then manoeuvre to a better landing spot. But I guess it relies on you have a signal and reacting quickly.

Is critical landing set to 25% battery by default? I used to have a Phantom 3 and I think I set it to 10%. Sadly, my Mavic was left at default for that setting.

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Replies in bold.

Can anyone confirm that default 25% critical battery setting? If so this is almost certainly what happened.

Still I'd really like to see the flight log. Any idea why the app crashes each time I click the icon?

 

[maikm]

Can anyone confirm that default 25% critical battery setting? If so this is almost certainly what happened.

Reading the manual can help. It states: "The low battery level failsafe is triggered when the DJI Intelligent Flight Battery is depleted to a point that may affect the safe return of the aircraft [...] The aircraft will land automatically if the current battery level can only support the aircraft long enough to descend from its current altitude."

So, it appears the level is variable.

 

[halley]

The aircraft will land automatically if the current battery level can only support the aircraft long enough to descend from its current altitude.

Here's where AGL vs ATO will bite you. It probably thought it needed enough battery to descend all the way to the take-off altitude, so it started quite a bit earlier than you expected. Meanwhile, it was really only about 10 meters over the rocks and ended up landing with some spare battery power. If only it could have glided downward on the way back toward home, it could have probably made it or gotten close enough a pedestrian hike was possible.

 

[Kilrah]

Critical battery level is 15% by default I believe. The % reading can't be perfect so there's always a risk it falls quicker than expected especially at the bottom of the scale, or that low voltage forces a landing even if capacity is still quite high.
You should get info on the controller and the possibility to abort or at least fight it depending on what actually gets triggered.

For the log, get the TXT file from the file browser.

 

[Pablo]

Reading the manual can help. It states: "The low battery level failsafe is triggered when the DJI Intelligent Flight Battery is depleted to a point that may affect the safe return of the aircraft [...] The aircraft will land automatically if the current battery level can only support the aircraft long enough to descend from its current altitude."

So, it appears the level is variable.

If that's the case then it might have kicked before it reached 15% battery as I was quite high up compared to the take off location (if only 20m from the ground). It's annoying though as I think the battery was probably at about 28% at that point and I could have flew it home with ease. As it dropped behind the rock very quickly after descending I never got another chance to cancel the landing. It was game over at that point.

 

[Pablo]

Critical battery level is 15% by default I believe. The % reading can't be perfect so there's always a risk it falls quicker than expected especially at the bottom of the scale, or that low voltage forces a landing even if capacity is still quite high.
You should get info on the controller and the possibility to abort or at least fight it depending on what actually gets triggered.

For the log, get the TXT file from the file browser.

I can see the TXT file. Any idea how I can export it so it's readable?

 

[Pablo]

Managed to upload it to healthy drones: HealthyDrones.com - Innovative flight data analysis that matters

So when it landed it was at 22%

 

[LawFlyer]

I live in Arizona and would be happy to go look for your Mavic...but I don't recognize that area. Can you post some info about where this happened?

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[LawFlyer]

Oh wow....just saw the HealthyDrones map.....yikes! That is unfortunately hours away from me....and not a safe area being so close to Mexico.

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[Kilrah]

Looks like Smart RTH engaged. You should have (and apparently did have) your 10 seconds to cancel it before it engaged, then you could always have stopped it later (until you lost connection a whole minute later).
Smart RTH plans the return so that it has landed by the time it reaches the set critical level, so it starts quite a bit earlier.

HD doesn't give the most important battery info, maybe post your TXT file here so other tools can be used?

 

[msinger]

Managed to upload it to healthy drones

You'll be able to see more data if you upload your TXT flight log here.

 

[Wacker2611]

I can't help Pablo, but v sorry for the loss as I remember how excited you were about the trip [emoji107]


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[halley]

Oh wow....just saw the HealthyDrones map.....yikes! That is unfortunately hours away from me....and not a safe area being so close to Mexico.

Well, HealthyDrones won't let me grab a KML of your flight but this is the spot in Google Earth. I can see why you would want to do that mission. (I don't know how a bloke from the UK drops into that part of Arizona for Christmas though!) The yellow circle is radius 500 meters, the default Litchi "safe" distance.

Same yellow circle visible southwest of Rio Rico.

I don't think that area is particularly dangerous, especially in the winter, unless @LawFlyer means the human-variety of coyote. Take water and boots for the hike.

 

[Pablo]

You'll be able to see more data if you upload your TXT flight log here.

Done: Phantom Log Viewer - PhantomHelp.com

Can't see too much extra information there to be honest. I would like to see confirmation that it auto-landed somewhere, but I don't.

I didn't ignore any return to home messages as has been suggested. Not as far as I'm aware anyway. I'm a fairly experienced flier, having had a P3 for over a year previously, so I've been in similar situations before without issue.

 

[Pablo]

Oh wow....just saw the HealthyDrones map.....yikes! That is unfortunately hours away from me....and not a safe area being so close to Mexico.

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Thanks very much for even considering it. I wouldn't have thought it's proximity to Mexico had any bearing on how safe it was to be honest, I was more worried about the non-human inhabitants! Had I been a local I might have just waded in, but I'm very much not, and the danger felt very real, especially as I was all on my own.