Hi,

My DJI died whilst flying under a bridge. it moved itself to the right instead of to the front, ignoring my commands while i was 20 meters away, also ignoring my correction (Full throttle) to the left. whilst being very close to the drone. In all other cases it did not pose a problem to fly under a bridge in an urban environment nor a narrow tunnel without gps with strong wind effects, as can be seen here.

This is inconsistent behavior at best and crappy programming at worst. Pilot control should be leading at all times, especially in the atti mode it changed into and if GPS loss was such a problem, it could have defered my vector (direction+speed) from just before losing gps.  The mavic before randomly took a plunge whilst stationary (reimbursed), the 2nd was losing connection within 400m range and not returning, the first suicided into a tree without my command right after takeoff. The 1st was reimbursed only after showing a video with my flight controls so they changed their conclusion that it is a compass error. but now they stick with their conclusion that the drone was controllable.

Are there any alternatives out there with similar camera quality and portability as the m2p which is not DJI?

I have a video. showing my controls at the accident, an earlier, similar accident, and cases where the mavic was functioning normally.

Attached are the flight logs of my last flight + the flight before where it did not return to home when it was supposed to but went moving further from home.

[URL unfurl="true"]https://cloud3.zoolz.com/s-iFyurjPd[/URL]

Hi,

Had a look at your flight.

Flying under that bridge, for short moment into ATTI, than P-GPS followed by OPTI.
But not sure if your 100% left-roll was to correct its flypath or....

See the values for GPS reception (columns GPS r) ; from steady 4 to 0, so craft not GPS stabilized at all.

In the first flight, during first part of the RTH input 100% forward while drone facing 180 degrees away from home, so ofcourse it went further away from HP.Input stopped, craft start to yaw to HP, yiou cancelled the RTH.

cheers
JJB

JJB* Posted at 3-4 10:53
Hi,

Had a look at your flight.

Thanks! Yes, that 100 % left was after little left wasn't listened to. Do you think this was due to compass error? You can see in the instance with the tree afterwards that this happened. DJI chose to reimburse that after showing the video (at first they only looked at flightlog and gave the costs to me), but not this one

The drone does what it is designed to do and the control is lost of what it can do under the bridge. The drone works the way is should do.

kyalami Posted at 3-4 11:02
The drone does what it is designed to do and the control is lost of what it can do under the bridge. The drone works the way is should do.

It is going to the right whilst it is supposed to go straight then goes to the right as i steer to the left with full force. Something strange going on. Compass error? or briefly touching atti mode made my controls non functional in the gps mode?

John Akerman Oumlzguumlccedil Posted at 3-4 11:08
It is going to the right whilst it is supposed to go straight then goes to the right as i steer to the left with full force. Something strange going on. Compass error? or briefly touching atti mode made my controls non functional in the gps mode?

This is strange, as even without GPS input, it should follow the way it would behave indoors. Perhaps DJI can assist better here.

John Akerman Oumlzguumlccedil Posted at 3-4 10:59
Thanks! Yes, that 100 % left was after little left wasn't listened to. Do you think this was due to compass error? You can see in the instance with the tree afterwards that this happened. DJI chose to reimburse that after showing the video (at first they only looked at flightlog and gave the costs to me), but not this one

Had a  second look

Forward speed under the bridge really low, about 0.4 m/s
Loosing good GPS means that craft cannot hold good position, so it started to move in directions around its position.

In this condition it is hard to control.

Change one parameter, now you see the move direction in the chart.
Polar chart center is just before entering the bridge....see how it moves, well   how the GPS data thinks it moves.

No compass error whatsoever, just a simple bad GPS data wich act on your drone.
cheers
JJB

kyalami Posted at 3-4 11:18
This is strange, as even without GPS input, it should follow the way it would behave indoors. Perhaps DJI can assist better here.

Not always....

If you fly in a stabilized GPS mode and the GPS signals are reflected etc  so the drone thinks it is not at the T minus 1 position before, if will correct its position to the new incorrect position, so it does not keep good steady flying track or hover position.

Calculations are going wrong, sometimes the VPS system does help to keep steady position, but not always. If calculations are really bad than drone will switch to ATTI mode.

cheers
JJB

VPS over water is hit or miss. Better to not count on it over water, especially when darker, like under a bridge.

Hello there John. I am sorry to read and to know what happened to your DJI Mavic 2 Pro and thank you for reaching out. Since this unfortunate incident happened. I would recommend for you to contact our DJI Support Team at https://www.dji.com/support?site=brandsite&from=nav for further assistance. If the said drone is still under the warranty period and it is evaluated as a non-pilot error, the warranty service will be provided. Again, I am sorry for your loss and thank you.

JJB* Posted at 3-4 11:56
Not always....

If you fly in a stabilized GPS mode and the GPS signals are reflected etc  so the drone thinks it is not at the T minus 1 position before, if will correct its position to the new incorrect position, so it does not keep good steady flying track or hover position.

Thanks for that extra explanation JJB. I just did not think of reflected GPS signals and what they can do under a bridge. In other words, do not fly under bridges. There are some other samples of mishaps under bridges in this forum.

kyalami Posted at 3-5 00:11
Thanks for that extra explanation JJB. I just did not think of reflected GPS signals and what they can do under a bridge. In other words, do not fly under bridges. There are some other samples of mishaps under bridges in this forum.

agree,  in general it is better not to fly under bridges.

But depends ofcourse of the type of bridge, this bridge was a closed structure low relative width bridge ; very likely to loose control of a gps stabilized drone.

cheers
JJB

JJB* Posted at 3-5 00:25
agree,  in general it is better not to fly under bridges.

But depends ofcourse of the type of bridge, this bridge was a closed structure low relative width bridge ; very likely to loose control of a gps stabilized drone.

Yes I can understand this. Just spoke to a fried who lost his drone under a bridge. It looked like he also lost the RC signal to the drone when it was under the bridge and as the drone was set to return to home at 50m, it went up against the ceiling of the bridge, as it tried to reach 50m and go home. It crashed against the ceiling and then lost it props and went down in the water and never to seen again. He now bought a new M2P and will never again fly under a bridge. Lesson learned the hard way.

kyalami Posted at 3-5 00:55
Yes I can understand this. Just spoke to a fried who lost his drone under a bridge. It looked like he also lost the RC signal to the drone when it was under the bridge and as the drone was set to return to home at 50m, it went up against the ceiling of the bridge, as it tried to reach 50m and go home. It crashed against the ceiling and then lost it props and went down in the water and never to seen again. He now bought a new M2P and will never again fly under a bridge. Lesson learned the hard way.

Interesting, but that exact scenario of the aircraft going into RTH and flying up and hitting the underside of the bridge has appeared from time to time, ever since these forums began.

Time for DJI to fix this in the firmware...

John Akerman Oumlzguumlccedil Posted at 3-8 02:51
Time for DJI to fix this in the firmware...

Time for DJI to fix this in the firmware...
Time for you to give up your fantasy and learn some facts
There was nothing in your incident that DJI can prevent with firmware.
The problem was the guy on the joysticks.

Labroides Posted at 3-8 04:29
Time for DJI to fix this in the firmware...
Time for you to give up your fantasy and learn some facts
There was nothing in your incident that DJI can come prevent with firmware.

If boeing or airbus messed up like this their aircraft would be grounded untill it has been proven safe, by the manufacturer. Don't blame me for unreliable aircraft operation, ignoring user commands. GPS hasn't been necessary in earlier instances in close quarters, even outdoor. The aircraft was aware i was trying to steer straight and then correct to the left.
As you can see here, i flew in way smaller caves/tunnels and it was acting like it should.
https://youtu.be/F9_InaWEDSE


Also the GPS argumentation is not very stable as i was already at the end of the bridge when the drone went haywire. from an angle of 10 degrees sattelites could already have picked up signal.

John Akerman Oumlzguumlccedil Posted at 3-8 04:57
If boeing or airbus messed up like this their aircraft would be grounded untill it has been proven safe, by the manufacturer. Don't blame me for unreliable aircraft operation, ignoring user commands. GPS hasn't been necessary in earlier instances in close quarters, even outdoor. The aircraft was aware i was trying to steer straight and then correct to the left.
As you can see here, i flew in way smaller caves/tunnels and it was acting like it should.
https://youtu.be/F9_InaWEDSE

If boeing or airbus messed up like this ..
You mean if Boeing or Airbus let totally unqualified, over-confident people fly their planes?
Hmm .. how's DJI going to control that?

Don't blame me for unreliable aircraft operation, ignoring user commands. GPS hasn't been necessary in earlier instances in close quarters, even outdoor.

The aircraft was aware i was trying to steer straight and then correct to the left.
Right there your are showing your complete ignorance of how the drone works.
It's one thing to wreck a number of drones through reckless flying, but to then blame the manufacturer you have to be an A-grade tosser.

DJI's tech people analysed your flight data and told you what the problem was.
You've posted your sorry story on three forums that I've seen and been advised of the facts of the incident.
But it couldn't possibly be your fault because you know better than everyone else.
How many more drones do you need to lose to wise up?

Lol, I'm qualified and not overconfident. If I were I would fly it full speed trough the tunnel.
No, the numerous drone fails mean there's lots of firmware work to do. fortunately in 2/4 cases DJI acknowledged this. But i'm not gonna be their guinea pig betatesting their unfinished product and shelling out 1200 euro each time they don't. Also my legal advisor and technician states this cannot be only due to GPS. Looking forward.

You are a diehard believer of the DJI Church ain't you.

DJI Stephen Posted at 3-4 19:07
Hello there John. I am sorry to read and to know what happened to your DJI Mavic 2 Pro and thank you for reaching out. Since this unfortunate incident happened. I would recommend for you to contact our DJI Support Team at https://www.dji.com/support?site=brandsite&from=nav for further assistance. If the said drone is still under the warranty period and it is evaluated as a non-pilot error, the warranty service will be provided. Again, I am sorry for your loss and thank you.

Effective Control: ☒Yes ☐No Directional Error: ☐Yes ☒No

Control Mode: ☒GPS Mode ☒ATTI Mode ☐OPTI Mode ☐Sport Mode
 Accident Type: I
☐ A. Pilot fault in Positioning Mode ☐ B. Pilot Fault in ATTI Mode
☐ C. Pilot fault when using intelligent flight ☐ D. Pilot fault when using App
☐ E. Aircraft crashed with obstacles when RTH ☐ F. Strong wind caused accident
☐ G. Add third-party component caused accident ☐ H. CSC operation in mid-air
☒ I. Other Aircraft crashed in weak GPS signal environment


Effective control at the time of crash was not there, as pointed out by the flight log.

Geebax Posted at 3-5 13:49
Interesting, but that exact scenario of the aircraft going into RTH and flying up and hitting the underside of the bridge has appeared from time to time, ever since these forums began.

Yes, interesting!

Same for crafts flying with low battery under trees or other height blocking objects,
'suddenly' low battery RTH engages, pilot surprise (uh??), too late to respond (cx RTH) and craft flys up and crashes.

Happend in the past, happens today and will happen in the future to remote pilots !  ;-)

cheers
JJB

Yes, is is amassing that we do not learn. By going back in this forum and looking what has happened previously, we should be able to avoid these mishaps.  In a way, is is good that this is brought up now and again, so that we, who are new to drones can learn, unless you read all the information in the manuals. Thank you.

JJB* Posted at 3-4 11:47
Had a  second look

Forward speed under the bridge really low, about 0.4 m/s

DJI decided  to reimburse after showing the first image to them. I highlighted two columns showing it was aware of my steering moves but didn't act accordingly. Dankjewel!

John Akerman Oumlzguumlccedil Posted at 3-17 04:44
DJI decided  to reimburse after showing the first image to them. I highlighted two columns showing it was aware of my steering moves but didn't act accordingly. Dankjewel!

if my charts helped to change the DJI analysis, so they decided to replace your drone; that is good news for you!

But i thought that is was just moving 'randomly' bc it lost GPS data...  never mind, DJI analyse is correct ofcourse  ;-)

But still   bad idea to fly under such bridges....well, just my 2-cents

And mayby they made a mistake....had a look again. After your roll left it showed 'braking now message' , to react on inputs again RC inputs has to go to zero first, that again it will react on input.  Your steady left input at the end had no effect bc the 'back to zero' did not happen....   ;-))   you are just a very lucky person!

cheers
JJB

For more on this incident take a look at
https://mavicpilots.com/threads/ ... page-2#post-1227431