Hello all,

I was out in the park flying my Mavic today and I found a little covered picnic area that I thought it would be a cool shot to fly through. I was flying through it slowly so that I didn't hit anything, but once I got close to the other side of it, the Mavic flew over the seat on one of the picnic tables. This caused the Mavic to rise up, right into the rafters and caused the Mavic to crash.

I watched the footage over and over, as well as the flight data, and you can see me holding full down on the left stick as it starts rising, but it doesn't stop. It keeps going up and crashes into the ceiling. Is this intended behavior? I would think that the Mavic should listen to my input saying to go down over the VPS system.

The Mavic itself seems to be fine other than a couple of cracked props and some scratches, but I'm wondering if this was a defect/glitch that caused this to happen or if this would be considered pilot error even though the VPS caused the crash and not my input.

I'm on iOS, so im not sure what the best way to get the flight data showing stick movements out of the app and onto this forum would be, if someone could point me to a tutorial that would be greatly appreciated.

Here is the video of the crash.
https://youtu.be/raxKO7lryHU

VPS is very sensitive, Ive had mine stop my aircraft when I was flying over a powerline once. Was very shocked that it picked up so small. Ive noticed if im flying a foot or two within a object im flying over the sensors will stop the aircraft. Its very possible that even though you werent going to hit anything the VPS system was still triggered. One thing I think would be helpful would be if DJI came out with some tips on when VPS should be disabled.. for example circumstances where you are flying close to objects, its functionallity is also very poor at sunset and the aircraft is not flyable around dusk with VPS enabled you will get many false VPS warning and interruptions.

After watching your video I would say this is not normal VPS behaivor. It is normally much more abrupt and it doesnt ever keep drifintg after avoidance, for me it usually just stops my aircraft in place.

Fractures Posted at 2017-4-12 09:18
VPS is very sensitive, Ive had mine stop my aircraft when I was flying over a powerline once. Was very shocked that it picked up so small. Ive noticed if im flying a foot or two within a object im flying over the sensors will stop the aircraft. Its very possible that even though you werent going to hit anything the VPS system was still triggered. One thing I think would be helpful would be if DJI came out with some tips on when VPS should be disabled.. for example circumstances where you are flying close to objects, its functionallity is also very poor at sunset and the aircraft is not flyable around dusk with VPS enabled you will get many false VPS warning and interruptions.

After watching your video I would say this is not normal VPS behaivor. It is normally much more abrupt and it doesnt ever keep drifintg after avoidance, for me it usually just stops my aircraft in place.

Thanks for your input, I'm thinking this was caused by the downward facing VPS system, not so much the obstacle avoidance.

DJI Ken or anyone else, can you weigh in to see if this is normal or abnormal behavior?

First instinct is to say that this was the Landing Protection feature. It acts kind of like downwards OA. When enabled, the Mavic will try to maintain a height of 0.5m from anything below, and that unfortunately means it can rise up into overhead obstacles. It's a feature that I don't like very much, since there are no upward facing sensors. I prefer to leave Landing Protection off.

In your case, it looks like it rose more than 0.5m, though. That could be just because of momentum or inaccurate VPS readings, but I also wonder if the Mavic may have gone into ATTI mode due to it being under that roof. Can you check the playback of your flight and see if it switched into ATTI mode, or if the GPS signal dropped significantly?

Jason Lane Posted at 2017-4-12 09:59
First instinct is to say that this was the Landing Protection feature. It acts kind of like downwards OA. When enabled, the Mavic will try to maintain a height of 0.5m from anything below, and that unfortunately means it can rise up into overhead obstacles. It's a feature that I don't like very much, since there are no upward facing sensors. I prefer to leave Landing Protection off.

In your case, it looks like it rose more than 0.5m, though. That could be just because of momentum or inaccurate VPS readings, but I also wonder if the Mavic may have gone into ATTI mode due to it being under that roof. Can you check the playback of your flight and see if it switched into ATTI mode, or if the GPS signal dropped significantly?

Hi Jason,

It did not go into ATTI mode, the GPS only dropped from 16 to 11-12 satellites. Looking at the flight logs, it looks like the height went from 6.6ft feet before I went under the roof, to 3.3 feet. Then, when I went over the table bench, it dropped to 0 which may have caused it to rise? I'm not sure here, but it's my best guess.
I'm thinking this might be related to the terrain follow feature.

Fractures Posted at 2017-4-12 09:18
VPS is very sensitive, Ive had mine stop my aircraft when I was flying over a powerline once. Was very shocked that it picked up so small. Ive noticed if im flying a foot or two within a object im flying over the sensors will stop the aircraft. Its very possible that even though you werent going to hit anything the VPS system was still triggered. One thing I think would be helpful would be if DJI came out with some tips on when VPS should be disabled.. for example circumstances where you are flying close to objects, its functionallity is also very poor at sunset and the aircraft is not flyable around dusk with VPS enabled you will get many false VPS warning and interruptions.

After watching your video I would say this is not normal VPS behaivor. It is normally much more abrupt and it doesnt ever keep drifintg after avoidance, for me it usually just stops my aircraft in place.

Sorry post was meant for OP

Use this link it explains how to do what your looking for, it might also help if you put up your flight log.

https://forum.dji.com/forum.php? ... &fromuid=260008

Use this link it explains how to do what your looking for, it might also help if you put up your flight log.

https://forum.dji.com/forum.php? ... &fromuid=260008

Having done this numerous times myself, I can say that's not normal in any mode. The downward sensors need to be much closer to command the Mavic up so high. Yours seems like it is detecting many feet vs 1.

That did look out of control. Jason probably right about the landing protection. If you're shooting gaps you probably want this off.

Looks to me like you lost GPS flying under the metal roof on the shelter???

You had a whole open field to fly in..............................................

broyuken Posted at 2017-4-12 10:45
Hi Jason,

It did not go into ATTI mode, the GPS only dropped from 16 to 11-12 satellites. Looking at the flight logs, it looks like the height went from 6.6ft feet before I went under the roof, to 3.3 feet. Then, when I went over the table bench, it dropped to 0 which may have caused it to rise? I'm not sure here, but it's my best guess.

Sounds like the Landing Protection kicked in, maybe further exacerbated by an inaccurate VPS height reading. For further analysis, the flight logs would be helpful. Here are a few ways to post flight logs:

- Screen recording of the app's flight playback (hallmark007 gave a link for how to do this)
- Post the app's flight log to Airdata (formerly HealthDrones) and PhantomHelp. See my post at the bottom of the thread that hallmark gave.
- If the app's flight log doesn't give enough data to pinpoint what happened, you can pull the .dat file from the Mavic and share it so that other users can take a look and analyze it.

To me it seems the downward sensors picked up the benches and the OA made it raise.

If you want to do this kind of things, you have to remember to always disable the OA/VPS... as it's prepared to avoid a crash only under normal circumstances, not when you're flying on a not-so-suitable place.

Did the mavic take too much damage? I hope not.

Jenee 2 Posted at 2017-4-12 22:40
You had a whole open field to fly in..............................................

haha and I did for 1.5 batteries, then I went for something a little more interesting
Added my flight log which shows me holding down on the left stick, as the Mavic went up
https://www.youtube.com/watch?v=tNqzGJhuYx0

CuaC Posted at 2017-4-12 23:05
To me it seems the downward sensors picked up the benches and the OA made it raise.

If you want to do this kind of things, you have to remember to always disable the OA/VPS... as it's prepared to avoid a crash only under normal circumstances, not when you're flying on a not-so-suitable place.

I cracked 2 props in the crash and the body got scuffed up a little, other than that it seems to be fine. Haven't gotten it back up in the air due to the lack of props, but everything else I've tested seems to be ok. Will be doing some low altitude tests over grass until I feel comfortable that it's fine.

Definitely looks like the Mavic's VPS thought the ground was very close, and the Landing Protection kicked in and caused it to ascend. The sensors aren't perfect, unfortunately :-(

broyuken Posted at 2017-4-13 06:05
haha and I did for 1.5 batteries, then I went for something a little more interesting
Added my flight log which shows me holding down on the left stick, as the Mavic went up
https://www.youtube.com/watch?v=tNqzGJhuYx0

From your reply, I think we can confirm that the bottom sensors sensed the ground. See how the ground clearance goes from 3.3 feet to 0 when in the video it starts going up. It probably sensed the bench as a ground obstacle and tried to avoid it.

broyuken Posted at 2017-4-13 06:05
haha and I did for 1.5 batteries, then I went for something a little more interesting
Added my flight log which shows me holding down on the left stick, as the Mavic went up
https://www.youtube.com/watch?v=tNqzGJhuYx0

Flying in areas were lighting changes are drastic may well have been your problem, it does mention this in the manual.

Sorry to say but I think this one is pilot error. The Mavic was already on its way up using OA to avoid the table when you pulled the throttle all the way down, probably too late to stop the ascent. Remember, the Mavic has no sensors at the top so it did not know there was a roof there. Your pulling the throttle back meant the Mavic still thought it was going to hit the obstacle and it was programmed to avoid it.

broyuken Posted at 2017-4-13 06:06
I cracked 2 props in the crash and the body got scuffed up a little, other than that it seems to be fine. Haven't gotten it back up in the air due to the lack of props, but everything else I've tested seems to be ok. Will be doing some low altitude tests over grass until I feel comfortable that it's fine.

It would be a good idea to calibrate the IMU and then the compass.  Sorry you had trouble and this should be a possible flight scenario, even if you loose the GPS. but another thing is you want to turn off RTH because if it lost GPS if could trigger the RTH and rise up to the set altitude ..

Rich