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Mavic 2 Flyaway Crash - Not Enough Force/ESC Error

There is another one to evaluate the local magnetic environment before take off as well.

Go into the settings in the app, advanced then Sensor Status.

Here you'll find a page with the IMU status and compass.

You'll see the green/yellow/red bar graphs with numbers. Assuming everything is correctly calibrated before this flight the compass should be single figures or at worst just into double figures green on the left. If the drone is near something magnetic such as rebar, electrical cabling, even some types of natural rock you'll see this number climb significantly higher and the graph move. This is visible well below the warning level generated. If you move the drone towards and away you can see this figure change in real time.

Part of the pre-takeoff checks should always be this screen to check the IMU status and the compass environment AND check the map orientation on top of that.
The map option is nice but isn;t always that useful. Some countries and areas dont allow offline caching of maps and in addition in some areas such as offshore there is little or no detail of small islands or rocks so you cant get a great idea of the nose orientation from that alone.
That, sir, is a brilliant reply. Out of all the flyaways and crashes you see described on this forum, i haven't ever seen that bit of simple advice given before. If it can actually tell you there is something going on before takeoff it's an absolute boon!! I have no idea if this is right or wrong but if it is, it sure sounds like an easy way round this whole problem that would only take a matter of seconds to check. What's everyones thoughts??? @sar104??
 
That, sir, is a brilliant reply. Out of all the flyaways and crashes you see described on this forum, i haven't ever seen that bit of simple advice given before. If it can actually tell you there is something going on before takeoff it's an absolute boon!! I have no idea if this is right or wrong but if it is, it sure sounds like an easy way round this whole problem that would only take a matter of seconds to check. What's everyones thoughts??? @sar104??

It's worth a look but not as definitive as checking the aircraft orientation arrow. Part of the problem is that we don't know what the compass interference indicator is actually measuring, or what kind of interference it is looking for. I guess it would be pretty easy to do a few tests by disturbing the magnetic field deliberately and then comparing the interference values with the actual magnetometer readings to try to infer the link.
 
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Question to Moderator(s) - in case @NerdGoingOutside isn't forwarding thread updates to e-mail, is there a way for you to send him an Administrative e-mail pointing him to the updates here?
I was wondering the same in sorts, If a Big Dog in charge could at least use his email to contact him and tell him about this post.
 
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Holy crap, I am shocked. @joshzdad is a saint. Four hours of grid searching on that terrain for a stranger?! Amazing. Between that and all the other support and knowledge folks on the forum have provided, especially @sar104 's expertise, I am super impressed.

Dude sent me pictures of the thing on Instagram and I was like !!!!!!!.

I've been busy with work and haven't been back for a week or so, catching up on the thread - the suggestions here are good, and I'm actually relieved to learn that this is preventable and not some bug in the drone's firmware that would make me wary to fly one again. I'd agree with what others have said - this was pilot error. I don't know that I'm convinced that hovering a few feet above the ground waiting for a GPS lock is a negligent practice, but certainly being ignorant of the potential from magnetic interference that doesn't trip a warning and failing to verify the compass heading was a significant error. I might argue that DJI could and should call this out with more specificity in a drone designed for the consumer market, but ignorance is certainly no one's fault but the ignorant.

Thanks to everyone for the knowledge sharing, and most special thanks to @joshzdad for putting in that kind of effort, ****. Still stunned by that one.
 
It's worth a look but not as definitive as checking the aircraft orientation arrow. Part of the problem is that we don't know what the compass interference indicator is actually measuring, or what kind of interference it is looking for.

I guess it would be pretty easy to do a few tests by disturbing the magnetic field deliberately and then comparing the interference values with the actual magnetometer readings to try to infer the link.

Its relatively easy to verify this, load the screen up then walk around putting the drone down where you know there's metal, wiring and so on. The numbers increase significantly and the graph moves significantly and drops down to single figures when in the clear. Its a quick way of seeing what is around your intended launch area.
Its possibly something simply like measuring the field strength above the previously calibrated background (in the way mobile phone apps will) but its useful for quickly evaluating a launch point.

The orientation arrow is handy (if you have access to maps, either online or offline and many places dont) and if the map actually has enough detail (offshore islands etc are very basic or dont show at all on offline cached maps for example).

You'd need a real compass to verify the arrow compass heading on the map. Which is possible but does need extra equipment and time.

I do both off a boat. Maps dont exist and are worthless so i have to use a compass but ALWAYS evaluate IMU and compass screens before taking off.
 
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Its relatively easy to verify this, load the screen up then walk around putting the drone down where you know there's metal, wiring and so on. The numbers increase significantly and the graph moves significantly and drops down to single figures when in the clear. Its a quick way of seeing what is around your intended launch area.
Its possibly something simply like measuring the field strength above the previously calibrated background (in the way mobile phone apps will) but its useful for quickly evaluating a launch point.

The orientation arrow is handy (if you have access to maps, either online or offline and many places dont) and if the map actually has enough detail (offshore islands etc are very basic or dont show at all on offline cached maps for example).

You'd need a real compass to verify the arrow compass heading on the map. Which is possible but does need extra equipment and time.

I do both off a boat. Maps dont exist and are worthless so i have to use a compass but ALWAYS evaluate IMU and compass screens before taking off.

I don't generally compare the arrow to details on the map - I just compare it to north. And if you are flying with a mobile device then you already have a compass to determine north if you don't already know which direction it is.
 
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That assumes the mobile compass is correctly calibrated. More often than not they're significantly out (android for sure).

Ive also seen situations where the drone is orientated correctly on the map but the magnetic graph is should a high error rate and figure (green but just) due to magnetic distortion nearby.
Using both would seem sensible to make sure the environment is the cleanest possible before taking off.
 
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That assumes the mobile compass is correctly calibrated. More often than not they're significantly out (android for sure).


G: FWIW, my iPhone compass has never asked to be calibrated and every time I've checked North, it was on the money. Perhaps the Android compass code has better system checking, who knows?
 
That assumes the mobile compass is correctly calibrated. More often than not they're significantly out (android for sure).

I've never encountered that problem. And I'm tempted to say that anyone incapable of identifying north prior to launching probably shouldn't be flying.

Ive also seen situations where the drone is orientated correctly on the map but the magnetic graph is should a high error rate and figure (green but just) due to magnetic distortion nearby.
Using both would seem sensible to make sure the environment is the cleanest possible before taking off.

If that's the case then it clearly indicates that the interference meter is not very useful. If there is actual distortion of the magnetic field then the chances of the direction arrow pointing correctly is very remote. I guess we are definitely going to have to disagree on this topic.
 
What an awesome story. Can't believe you found it haha. NerdGoingOutside you contact DJI with proof pics yet?
There was a great story about an sd-card recovery below Half Dome in Yosemite National Park. Folks "climbing" the ladder/cables are always losing their grip on something like a water bottle or clothing item or camera. Someone decided to clean up on the slopes below - not an easy locale. They found the memory card and through a bit of posting and sleuthing actually found the owner.
 
If that's the case then it clearly indicates that the interference meter is not very useful. If there is actual distortion of the magnetic field then the chances of the direction arrow pointing correctly is very remote. I guess we are definitely going to have to disagree on this topic.

Or it hints that although the drone is roughly orientated its on the edge of not being so and there maybe an unacceptably high risk of it getting worse during or just after launch.
 
Or it hints that although the drone is roughly orientated its on the edge of not being so and there maybe an unacceptably high risk of it getting worse during or just after launch.

No - that's not what causes the yaw and compass errors. It's not distortion in flight - it's distortion at the takeoff point leading to incorrect IMU yaw initialization. Provided that the IMU yaw is correctly initialized, whether or not there is interference, the flight is unlikely to have problems.
 
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Drone received! I've been itching to get my hands on it all week, but work hours prevented me from getting to the post office. This morning I went down and retrieved it, lovingly wrapped for its journey by @joshzdad.

All in all, she held up pretty well after that 50 mph impact and a long winter buried in snow. The front left propeller strut is completely snapped and hanging by a couple of wires. The propeller on that motor is completely snapped off at the base, and one of the other props has a significant gouge. The gimbal is hanging looser than it should and I expect something is broken there. There is a little bit of swelling at some of the seams in the case, but all in all it held together well. DJI Care Refresh case is created, and I'll be mailing it back to DJI this week.

The coolest part: I hadn't considered until I had it in my hands that the SD card might be intact... and it is! One video I took of my campsite early in the morning is completely intact, and I'm glad to have it. The video that was recording at the time of the crash is over 700MB, but is hopelessly corrupted and wouldn't play. I tried a ton of video recovery software solutions, and finally found one that was able to recover most of the video of the poor thing slamming into that mountainside. Once I get it processed I'll post it here for all to see.

In the meantime, a sneak peak at the kind of terrain @joshzdad had to climb over to find her - amazing. You're a saint.

69352
 
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Drone received! I've been itching to get my hands on it all week, but work hours prevented me from getting to the post office. This morning I went down and retrieved it, lovingly wrapped for its journey by @joshzdad.

All in all, she held up pretty well after that 50 mph impact and a long winter buried in snow. The front left propeller strut is completely snapped and hanging by a couple of wires. The propeller on that motor is completely snapped off at the base, and one of the other props has a significant gouge. The gimbal is hanging looser than it should and I expect something is broken there. There is a little bit of swelling at some of the seams in the case, but all in all it held together well. DJI Care Refresh case is created, and I'll be mailing it back to DJI this week.

The coolest part: I hadn't considered until I had it in my hands that the SD card might be intact... and it is! One video I took of my campsite early in the morning is completely intact, and I'm glad to have it. The video that was recording at the time of the crash is over 700MB, but is hopelessly corrupted and wouldn't play. I tried a ton of video recovery software solutions, and finally found one that was able to recover most of the video of the poor thing slamming into that mountainside. Once I get it processed I'll post it here for all to see.

In the meantime, a sneak peak at the kind of terrain @joshzdad had to climb over to find her - amazing. You're a saint.

View attachment 69352
RIGHT ON!!!!!! I can't wait to see the unfortunate end. bitter sweet?
 
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