Mavic 2 Pro Wild Ride....

[CrouchyUK]

Hi chaps- I'm a bit of a lurker here and feel embarrassed to ask for help- but here goes....

I've had my M2P for 9 months or so now, and a Mavic for 18 months before that. I like to think I fly conservatively- never had a crash, fly-away or had anything happen with the drone that I didn't understand. But now my confidence is a bit dented until I find out what I did wrong- I would appreciate someone looking at the flight logs and explain what happened?

Best if I explain what I thought was happening at the time- looking with an untrained eye at the txt files obviously something entirely different was actually going on.!

Final day on holiday in Cyprus and my last chance to get a cool shot of the sunset through the superstructure of a well known wreck off Paphos. I videoed the wreck comprehensively last year with no problems- this year a few days previous there was too much haze on the horizon so the attempt abandoned.

Weather was of course glorious and with a very light onshore breeze I thought perfect for a safe flight. Always when flying at home I will set my take-off position so the drone goes out into any wind and returns home with its assistance.

The previous day I had been flying around some tall structures elsewhere- so RTH was set at 70m and I planned to lower this to something more suitable once the drone was powered up- 20m being plenty for a flight over the sea and me only a few feet above sea level. However, a few glitches made me forget to do this- my mistake. At first when I arrived at the launch point my partner noticed another drone in the air and we saw the pilot 100m or so away, so as I have never flown with another drone nearby I went over to introduce myself and swap plans. He had a Mavic up getting shots of the same wreck, so we talked about me flying out and back on the north side, and he keeping to the south side. In any event by the time I got back to my launch point he had landed the Mavic and was walking way. But I was still unsure as to whether we could have both flown at the same time without interference. Now the sun was dropping fast to the horizon….

Next, when I powered up the M2P it demanded a compass calibration- as it does every time unlike my old Mavic and it is annoying- have I since read here on the forum this is normal? Sun still dropping to the horizon….

Compass calibration done- about to take off when I noticed no video image on the SC- a few minutes twiddling with shutter, aperture and ISO still got no visible image- then I noticed the camera pointing past vertical down at the ground- it wouldn’t respond to the controls and move up. Picking the drone up it was apparent that my Freewell variable ND filter had fouled on gimbal initialisation- but no alarm given? It freed up with a quick nudge, but I thought it best to reboot the drone- this time the gimbal initialised with no issues. Again- I have since seen on here that there are issues with these Freewell filters. Sun still dropping…

Finally taking off a bit rushed and flustered- as mentioned I forgot to change the RTH height- the drone headed out normally to the wreck. As the drone approached the wreck I slowed and dropped height- trying to get the sun in the right position. I recall that this was a bit difficult- it seemed to overshoot or not move normally as I see-sawed left and right. I got one still which was not aligned as the drone appeared to drift off line as I took the shot.

I then noticed the drone drifting around without input from me, following which it rotated left and set off on an uncommanded flight back to the coast at speed. As it had only been at 30ft or so my first concern was it was heading back inland at such a low height- and it seemed the only aspect of its flight I had any control over was the height and I managed to get it to ascend. We heard and saw it go past us left to right and then head back out to sea in a curve. During this time (panic!) all I could think of was that it seemed to be obeying some other controller- and heading out to sea. Maybe the other guy had returned and we were interfering with each other!

I pushed the RTH button- but I do not recall seeing or hearing any confirmation of this, so convinced was I that I was no longer controlling my drone I tried Sports mode- but still the drone was off on its own wild ride. Finally- as I had lost sight of it, didn’t know where it was or where it was going- and convinced I was not in control- I rebooted the SC. I remember turning to my partner and saying “That’s it- I’ve lost it”. Thinking that it might just return on loss of signal.

Then we heard it approaching and the SC chipped in with RTH beeps, and from then on it responded normally and tracked back to the Home Point at a reasonable speed. Scared the crap out of me TBH!

There are 2 txt files- before and after the SC reboot. I’ve obviously seen some of the speeds and attitudes reported on the flight record and it amazes me. 70mph! Again- all through this we were sat on a wooden platform on the shoreline, within 2000ft of the drone at all times enjoying a pleasant sunset with no or just a gentle onshore breeze.

Grateful for any insight or lessons to be learned….

DJI Flight Log Viewer - PhantomHelp.com

DJI Flight Log Viewer - PhantomHelp.com

 

[ZX14-R]

A Video would have been more fun

 

[thinglenn40]

Glad you got it back! I wasn’t so lucky!

 

[DanMan32]

Having to calibrate your M2 each flight is not normal. Some productions of M2 do ask for it every 30 days or 30 miles (KM?) from last flight but that's it.

Your M2 may have gotten magnetized and in need of demagnetising. That can happen if stored near magnets like a speaker.

 

[Gryphon962]

Can you post the .DAT file? Your log shows problems with the motor controllers (ESC) running out of force. All the details on what the motors are commanded to do, and doing, are in the .DAT file.

That should give sar104 or one of the other experts in here enough to go on.

 

[CrouchyUK]

A video of the flight would have been fun I admit! I have footage of the flight out, but then switched to stills for the shots I wanted. Reviewing the video shows a nice calm sea- nothing to indicate adverse weather. The one still photo I got shows the sun misaligned through the wreck- the drone drifted uncommanded whilst pressing for auto-focus even.

Previous flight to this WAS more than 30km away- so my M2P one of the ones that requires compass calibration in this way? Certainly I remember I only ever have to do it once per day on the first flight of any series in one place...

DAT files- it took me long enough to figure out the txt files thing! Attached all the DAT files that have the same date- I am thinking some of these are the initial drone reboots to sort out the gimbal problem but none of the timestamps agree with any of the txt's..

Thanks for the comments!

 

[Moose1967]

Yes please add YouTube link

 

[RickinWaST]

Your experience, even though there was no crashed/lost drone, is one nobody wants! Good luck in getting some answers!

 

[John Lord]

Hi chaps- I'm a bit of a lurker here and feel embarrassed to ask for help- but here goes....

I've had my M2P for 9 months or so now, and a Mavic for 18 months before that. I like to think I fly conservatively- never had a crash, fly-away or had anything happen with the drone that I didn't understand. But now my confidence is a bit dented until I find out what I did wrong- I would appreciate someone looking at the flight logs and explain what happened?

Best if I explain what I thought was happening at the time- looking with an untrained eye at the txt files obviously something entirely different was actually going on.!

Final day on holiday in Cyprus and my last chance to get a cool shot of the sunset through the superstructure of a well known wreck off Paphos. I videoed the wreck comprehensively last year with no problems- this year a few days previous there was too much haze on the horizon so the attempt abandoned.

Weather was of course glorious and with a very light onshore breeze I thought perfect for a safe flight. Always when flying at home I will set my take-off position so the drone goes out into any wind and returns home with its assistance.

The previous day I had been flying around some tall structures elsewhere- so RTH was set at 70m and I planned to lower this to something more suitable once the drone was powered up- 20m being plenty for a flight over the sea and me only a few feet above sea level. However, a few glitches made me forget to do this- my mistake. At first when I arrived at the launch point my partner noticed another drone in the air and we saw the pilot 100m or so away, so as I have never flown with another drone nearby I went over to introduce myself and swap plans. He had a Mavic up getting shots of the same wreck, so we talked about me flying out and back on the north side, and he keeping to the south side. In any event by the time I got back to my launch point he had landed the Mavic and was walking way. But I was still unsure as to whether we could have both flown at the same time without interference. Now the sun was dropping fast to the horizon….

Next, when I powered up the M2P it demanded a compass calibration- as it does every time unlike my old Mavic and it is annoying- have I since read here on the forum this is normal? Sun still dropping to the horizon….

Compass calibration done- about to take off when I noticed no video image on the SC- a few minutes twiddling with shutter, aperture and ISO still got no visible image- then I noticed the camera pointing past vertical down at the ground- it wouldn’t respond to the controls and move up. Picking the drone up it was apparent that my Freewell variable ND filter had fouled on gimbal initialisation- but no alarm given? It freed up with a quick nudge, but I thought it best to reboot the drone- this time the gimbal initialised with no issues. Again- I have since seen on here that there are issues with these Freewell filters. Sun still dropping…

Finally taking off a bit rushed and flustered- as mentioned I forgot to change the RTH height- the drone headed out normally to the wreck. As the drone approached the wreck I slowed and dropped height- trying to get the sun in the right position. I recall that this was a bit difficult- it seemed to overshoot or not move normally as I see-sawed left and right. I got one still which was not aligned as the drone appeared to drift off line as I took the shot.

I then noticed the drone drifting around without input from me, following which it rotated left and set off on an uncommanded flight back to the coast at speed. As it had only been at 30ft or so my first concern was it was heading back inland at such a low height- and it seemed the only aspect of its flight I had any control over was the height and I managed to get it to ascend. We heard and saw it go past us left to right and then head back out to sea in a curve. During this time (panic!) all I could think of was that it seemed to be obeying some other controller- and heading out to sea. Maybe the other guy had returned and we were interfering with each other!

I pushed the RTH button- but I do not recall seeing or hearing any confirmation of this, so convinced was I that I was no longer controlling my drone I tried Sports mode- but still the drone was off on its own wild ride. Finally- as I had lost sight of it, didn’t know where it was or where it was going- and convinced I was not in control- I rebooted the SC. I remember turning to my partner and saying “That’s it- I’ve lost it”. Thinking that it might just return on loss of signal.

Then we heard it approaching and the SC chipped in with RTH beeps, and from then on it responded normally and tracked back to the Home Point at a reasonable speed. Scared the crap out of me TBH!

There are 2 txt files- before and after the SC reboot. I’ve obviously seen some of the speeds and attitudes reported on the flight record and it amazes me. 70mph! Again- all through this we were sat on a wooden platform on the shoreline, within 2000ft of the drone at all times enjoying a pleasant sunset with no or just a gentle onshore breeze.

Grateful for any insight or lessons to be learned….

DJI Flight Log Viewer - PhantomHelp.com

DJI Flight Log Viewer - PhantomHelp.com

I am of the firm opinion that there is a bug in the flight control system of the Mavic 2 that DJI are not owning up to. There have been several instances where control of the Mavic 2 has been lost and the craft has either crashed, or if the owner is fortunate the craft has returned home. The common factor is the Mavic 2 has been flown at around 30ft over water. A friend lost his Mavic 2 Pro in an alligator inhabited lake in Florida on 4th May. DJI Care Refresh did not want to know as in their exclusions loss is not covered, even though it can be proven the craft was lost. DJI Customer Support claimed the crash was caused by the pilot applying left rudder and right aileron and hence was pilot error. Such inputs are common practice when flying anti-clockwise around a POI. The lesson learned is that DJI Care Refresh is a waste of money and a separate insurance is better and Customer Support are a bunch of crooks.

 

[Gryphon962]

I am of the firm opinion that there is a bug in the flight control system of the Mavic 2 that DJI are not owning up to. There have been several instances where control of the Mavic 2 has been lost and the craft has either crashed, or if the owner is fortunate the craft has returned home. The common factor is the Mavic 2 has been flown at around 30ft over water. A friend lost his Mavic 2 Pro in an alligator inhabited lake in Florida on 4th May. DJI Care Refresh did not want to know as in their exclusions loss is not covered, even though it can be proven the craft was lost. DJI Customer Support claimed the crash was caused by the pilot applying left rudder and right aileron and hence was pilot error. Such inputs are common practice when flying anti-clockwise around a POI. The lesson learned is that DJI Care Refresh is a waste of money and a separate insurance is better and Customer Support are a bunch of crooks.

Harsh.

From a business perspective, DJI has to protect itself against fraud. If Care Refresh allowed you to get a new drone without supplying the one you broke, some people would break their drones up and sell the parts then claim they lost the drone.

 

[Citizen Flier]

I am of the firm opinion that there is a bug in the flight control system of the Mavic 2 that DJI are not owning up to. There have been several instances where control of the Mavic 2 has been lost and the craft has either crashed, or if the owner is fortunate the craft has returned home. The common factor is the Mavic 2 has been flown at around 30ft over water. A friend lost his Mavic 2 Pro in an alligator inhabited lake in Florida on 4th May. DJI Care Refresh did not want to know as in their exclusions loss is not covered, even though it can be proven the craft was lost. DJI Customer Support claimed the crash was caused by the pilot applying left rudder and right aileron and hence was pilot error. Such inputs are common practice when flying anti-clockwise around a POI. The lesson learned is that DJI Care Refresh is a waste of money and a separate insurance is better and Customer Support are a bunch of crooks.

I crashed my M2P, and was able to locate. Received a replacement in less than 7 days. I thought that was some darn fine customer service. As another poster pointed out, DJI would likely be scammed if they left loopholes. For years REI allowed return of any item at any time. But that privilege was abused, and has now been amended. DJI isn't perfect, but I've dealt with tech issues with a range of manufacturers, and DJI's at the top of the list IMO.

 

[John Lord]

Harsh.

From a business perspective, DJI has to protect itself against fraud. If Care Refresh allowed you to get a new drone without supplying the one you broke, some people would break their drones up and sell the parts then claim they lost the drone.

But the evidence from the data showed clearly the aircraft was indeed lost in the lake. DJI Customer Support also confirmed in their response that the height indicated to the pilot is “relative” and cannot be relied upon. DJI declined to confirm what it is relative to. If correct, this means that a pilot could easily exceed the maximum permitted height (400ft in the UK) if they close to that height. DJI Customer Support also dismissed two instances of the craft switching to the backup IMU and also several instances of ”Upward Obstacle“ detection even thought there was nothing above the aircraft. The criticism of DJI Customer Support is therefore certainly not harsh. It is clear they did not want to admit there is an inherent issue with their product as it potentially could open the flood gates for claims, instead they are happy to let the customer take the pain.

 

[DanMan32]

By relative, they mean height is base from takeoff. If you rose 50' above takeoff, went straight above a 30' hill, your reading would still be 50', but your actual AGL would be 20'. They can dispute your height because there's no way to record change in terrain.
VPS height reading is rather accurate as it is using sensors to read the ground beneath it. However it has very limited range and can be fooled over water.

Being over legal height limit shouldn't have any bearing on a warranty crash claim unless geofence altitude limit was involved in causing the crash.

 

[Gryphon962]

....
DJI Customer Support also dismissed two instances of the craft switching to the backup IMU and also several instances of ”Upward Obstacle“ detection even thought there was nothing above the aircraft.
...

The obstacle sensors often trigger on insects, birds, etc.

The backup IMU is there to save the day if the primary IMU is deemed to be out of whack.

From what I've read in these forums, most drone losses are pilot related. That includes the pilot not doing what they should have done, or doing what they shouldnt do, when the drone encounters a problem. In those cases where the drone really does fail in flight, the guys in here are often able to see the smoking gun in the logfiles and the owners have used that analysis to get DJI to replace the drone even if not recovered. However, the analysis usually reveals that the pilot didnt do what they thought they did. Very common errors are:

1) Not checking home point is where you are when you take off
2) Taking off with depleted battery
3) Expecting the drone to fly back home into a very strong wind blowing faster than it goes
4) Not switching to Sport mode as an immediate action to recover control if drone does 'unexpected' things
5) Not holding down the RTH button until controller starts bleeping, then leaving it alone, if you want the drone to RTH

 

[CrouchyUK]

This is the brief video I shot on the flight out to the wreck. It shows nothing exceptional and I include it only because to me it shows calm conditions and nothing that would suggest a cause for the excessive speeds that occured immediately after. The (only) still photo I took whilst jockeying for position is tagged on the end- straight after this the drone went for its ride.

I have now read a few reports and claims on here of unusual things happening to peoples drones whilst flying low over water? I'm not convinced- although I am less inclined to think a mystery tornado or wind gust took my drone- which my first study of the flight logs seemed to suggest. Pilot error is of course still possible and I would be the first to admit my actions and reactions could have been better.

I am still hoping the txt and dat files will allow an expert to assist me further....

 

[John Lord]

By relative, they mean height is base from takeoff. If you rose 50' above takeoff, went straight above a 30' hill, your reading would still be 50', but your actual AGL would be 20'. They can dispute your height because there's no way to record change in terrain.
VPS height reading is rather accurate as it is using sensors to read the ground beneath it. However it has very limited range and can be fooled over water.

Being over legal height limit shouldn't have any bearing on a warranty crash claim unless geofence altitude limit was involved in causing the crash.

DJI were implying that although the data showed the height as being 33ft, which clearly was the lake as the Mavic 2 was flown from an airboat, the height may not have been 33ft. Visually the Mavic 2 was at that height. The issue is that there were some cypress trees in the lake but the maximum height of these was 20ft so DJI are saying that it crashed into a tree, even though it supposedly has obstacle avoidance. I saw what happened and it most certainly did not fly into a tree as it was not close to the trees and in any case it was some 10ft above the height of the tallest tree. I have come to the conclusion that with DJI Customer Support it is down to luck as to whether you get a replacement. If you happen to get a technician that got out of bed the wrong side that morning then you are not going to get anywhere but if you are lucky and get a technician that is reasonable then you do stand some chance. I also have it in writing from DJI Customer Support that they only look at the data when analysing the cause of a crash and do not take into account eye witness reports. This is contrary to all forms of accident investigation that I am aware of. As far as I am concerned DJI produce some excellent products but unfortunately are completely let down by the condition/exclusions in Care Refresh and also Customer Support.

 

[Gryphon962]

DJI were implying that although the data showed the height as being 33ft, which clearly was the lake as the Mavic 2 was flown from an airboat, the height may not have been 33ft. Visually the Mavic 2 was at that height. The issue is that there were some cypress trees in the lake but the maximum height of these was 20ft so DJI are saying that it crashed into a tree, even though it supposedly has obstacle avoidance. I saw what happened and it most certainly did not fly into a tree as it was not close to the trees and in any case it was some 10ft above the height of the tallest tree. I have come to the conclusion that with DJI Customer Support it is down to luck as to whether you get a replacement. If you happen to get a technician that got out of bed the wrong side that morning then you are not going to get anywhere but if you are lucky and get a technician that is reasonable then you do stand some chance. I also have it in writing from DJI Customer Support that they only look at the data when analysing the cause of a crash and do not take into account eye witness reports. This is contrary to all forms of accident investigation that I am aware of. As far as I am concerned DJI produce some excellent products but unfortunately are completely let down by the condition/exclusions in Care Refresh and also Customer Support.

Recommend you start another thread and post the .txt and .dat logs of the incident you are discussing. Its highly likely that someone will be able to plot what happened and see if there is any evidence to take back to DJI.

 

[Gryphon962]

....

I then noticed the drone drifting around without input from me, following which it rotated left and set off on an uncommanded flight back to the coast at speed. As it had only been at 30ft or so my first concern was it was heading back inland at such a low height- and it seemed the only aspect of its flight I had any control over was the height and I managed to get it to ascend. We heard and saw it go past us left to right and then head back out to sea in a curve. During this time (panic!) all I could think of was that it seemed to be obeying some other controller- and heading out to sea. Maybe the other guy had returned and we were interfering with each other!

I pushed the RTH button- but I do not recall seeing or hearing any confirmation of this, so convinced was I that I was no longer controlling my drone I tried Sports mode- but still the drone was off on its own wild ride. Finally- as I had lost sight of it, didn’t know where it was or where it was going- and convinced I was not in control- I rebooted the SC. I remember turning to my partner and saying “That’s it- I’ve lost it”. Thinking that it might just return on loss of signal.

Then we heard it approaching and the SC chipped in with RTH beeps, and from then on it responded normally and tracked back to the Home Point at a reasonable speed. Scared the crap out of me TBH!

There are 2 txt files- before and after the SC reboot. I’ve obviously seen some of the speeds and attitudes reported on the flight record and it amazes me. 70mph! Again- all through this we were sat on a wooden platform on the shoreline, within 2000ft of the drone at all times enjoying a pleasant sunset with no or just a gentle onshore breeze.

Grateful for any insight or lessons to be learned….

DJI Flight Log Viewer - PhantomHelp.com

DJI Flight Log Viewer - PhantomHelp.com

I'm not the expert, but as the right guys arent around, this is what I see from your log in the views you posted.

With reference to the first plot, all looks good until

2:26.6 - controls go to center, but the attitude is well off level - could be wind?
2:37.5 - uncommanded yaw left
2:46 - uncommanded acceleration
2:48 - commanded height increase - and it climbs
2:53 - its now doing over 50mph with right stick in center

..and after that it seems to be getting intermittent control inputs, but nearly always full stick when you see that. Lots of stuff happening despite sticks in middle. Mode is P-GPS throughout (would be understandable if it was ATTI mode)

3:33 - it announces a RTH but carries on slowly gyrating with (mostly) no control input
3:46 - Sport mode - but still looks out of control - which is troubling as Sport mode should give you enough control authority to get it under control

Unfortunately I cannot open what I think is the appropriate DAT file to dig deeper. Hopefully others will be able to point to a fault like an IMU crapping out, or something.

 

[DanMan32]

DJI were implying that although the data showed the height as being 33ft, which clearly was the lake as the Mavic 2 was flown from an airboat, the height may not have been 33ft. Visually the Mavic 2 was at that height. The issue is that there were some cypress trees in the lake but the maximum height of these was 20ft so DJI are saying that it crashed into a tree, even though it supposedly has obstacle avoidance. I saw what happened and it most certainly did not fly into a tree as it was not close to the trees and in any case it was some 10ft above the height of the tallest tree. I have come to the conclusion that with DJI Customer Support it is down to luck as to whether you get a replacement. If you happen to get a technician that got out of bed the wrong side that morning then you are not going to get anywhere but if you are lucky and get a technician that is reasonable then you do stand some chance. I also have it in writing from DJI Customer Support that they only look at the data when analysing the cause of a crash and do not take into account eye witness reports. This is contrary to all forms of accident investigation that I am aware of. As far as I am concerned DJI produce some excellent products but unfortunately are completely let down by the condition/exclusions in Care Refresh and also Customer Support.

Again, DJI is correct about the possibility of your height not being what you thought it was.

I agree it wouldn't seem likely that lake surface would be at a different height than from takeoff point, it is possible.

Also I have seen displayed altitude drift from actual, and to the negative. So yes, it could say you're 33ft when you're actually less than that. They may have felt leaving a 13ft margin was not enough to be certain you'll clear the trees.

I'm not saying height was the cause of the issue, just that displayed height isn't as precise as you seem to think it is. You can't necessarily just say you show to be 33ft so you're guaranteed to clear a 20ft tree 500ft away.

You may have had marginal magnetic interference on takeoff which messes up the IMU once you clear the interference.

Logs will help figure out what happened.

 

[Pyrodemon]

As was posted before DJI has the final say as to whether they will warranty a manufactured defect or just say it is pilot error. I was demonstrating my Mavic 2 to a co-worker and a client, showed them how the arms all fold out. Did all my checks, Mavic lifted off, hovered for 30 seconds, climb to 44 metres, went 69 metres horizontally, loud sounds start coming from the Mavic, Watched it rollover and crash. Picked up the drone, right rear arm was broken off, rear props still attached, front arms extended, props broke off and lying with in 2 metres of the Mavic. When I picked up the drone I turned the left motor and it felt stiff like a bearing had seized. Sent the Mavic to DJI, they analyzed the flight data said there was vibration in the left motor before lift off and that during the short flight the left arm collapsed causing it to crash. Pilot error is their determination of the flight data. I asked them to send me the flight data and all other related files, as I didn't downloaded it before I sent it to them. Their reply was that they would not send the data files as "it is classified information".

I have checked the internet for other mavic crashes and have found a number where the Mavic has suddenly rolled over during flight and crashed for no apparent reason. DJI refuses to admit there may be a problem with the motor. I have talk to other drone companies. One company bought 3 M200 and all 3 of them crashed with in 6 months under similar circumstances, DJI said the would only fix one under warranty and when it was returned DJI hadn't fixed the issue.