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Major problem, what happened?!
938 32 2018-8-23
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hugoleveille
lvl.3
Flight distance : 370174 ft
Canada
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Hi

Did a flight today with major problems with almost all possible errors in a few seconds

Context: I went in a empty field with no electricity, building nearby to test a range extender for the mavic air (just the simple 10$ extender on the remote). Perfect sunny day with minimal wind. The goal was to test range so of course I was flying w/o LOS.

So I went in a direct straight line for several minutes. Perfect flight with incredible reception. I was at 2600m (50m high) when I decided it was enough and was time to come back. Started a small turn to the left and BOOM! Multiple IMU errors. Drone looked like it was falling from sky.

After regaining control, I manually headed home to avoid any RTH error and noticed drone was not flying straight. Had to compensate alot cause it was drifting to the left. Also, I went in sport mode in some part when it was stable again to make it home ASAP.

I will try to extract log but right now its not working

I uploaded the video from sd card:  
And the flight record from the app with error message and control input:


In the video and flight record video, the problem is at : 5:35


When I was almost back, I had another IMU error and the drone drifted alot, had to fight with it.

You can see this at in the video at 9:10 and at 8:40 in the flight record


I will try to extract the log asap, but if someone got an idea of what happened.... I had this kind of problem once before, but then was able to do several normal flights after without problem.

2018-8-23
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gnirtS
Captain
Flight distance : 2993497 ft
United Kingdom
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Upload the log files to phantomhelp.com for us to see.
2018-8-23
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hugoleveille
lvl.3
Flight distance : 370174 ft
Canada
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Will try asap, but for now have this problem: https://forum.dji.com/thread-162905-1-1.html
2018-8-23
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gnirtS
Captain
Flight distance : 2993497 ft
United Kingdom
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OK cant help with that because there isnt a chance in hell i'd ever buy or use any device made by apple!

If you sort it and get the logs up, leave a link in here for us.
2018-8-23
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hugoleveille
lvl.3
Flight distance : 370174 ft
Canada
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Here is the log!

http://www.phantomhelp.com/LogViewer/145NXXD9WFYDWMXZHCMR/
2018-8-23
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PatrickM923
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Well, I wonder if this might help...(however,  I am an avid Apple user, so perhaps there isn't much chance my thoughts will be of much help at all).

Without further digressions, I see in your log files that you were at about roughly 70% of the published range of the Mavic Air (MA), and everything seemed to be going well at that point, and continued to go well until you got to the trees.  I wonder if you were then at the end of the range for the MA, and that perhaps the trees caused a change in terrain at that range, which in turn caused some difficulty for the RC.  What do you think?  Perhaps if you had skirted around the trees, and more in the direction of that McDonald's to the west, those problems would not have occured when they did, though with a published range of ~ 2.5 miles I think you were skirting the edges of the MA capabilities and some sort of loss of signal problem was likely to present itself soon.

Also, I noticed that you are at one of the edges, or boundaries, of the gas station parking lot. From that vantage point, It is difficult, at the end of the video, to see if you have good "line of sight" with the MA.  If your line of sight was impeded by foliage or other objects, then perhaps the signal with the MA was even more obscured and impeded between the RC and the MA.  Just Sayin'.

Another also....how were the Remote Controller's Antennae oriented?

By the way....very nice video....I liked it and watched it twice.  :-)
California USA
2018-8-23
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nixuspix
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So everything happened while you were over the trees and started return to home. First message was about strong wind and you just started to yaw your drone ! So may be these 2 factors together ( wind+Yaw) destabilised your IMU  and the drone went to ATTI mode. As soon as you crossed the forest border and flew to the open field again, things returned to normal
2018-8-23
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hugoleveille
lvl.3
Flight distance : 370174 ft
Canada
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Thank you both for taking the time to check log. Really appreciated.

About the range. Yes I was very far, but distance should not modify drone stability in any way right?  

And the trees, I understand it can interfere with reception, but how could that messed up the IMU that much?

Also, things did not return to normal after clearing trees. You can see near the end of the video that drone is drifting alot and had another IMU error while I was at 400m

Again thanks again for the help
2018-8-24
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gnirtS
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Im having issues loading the text file into the analysis program ( @jjbspark ).
But from the logs yes theres a sporadic wind warning but nothing to be worried about.

I cant graph the data on FRAP as i cant get it to read but looking at the excel its odd.  Its not wifi or GPS reception related.

The big lump of errors from different systems together is odd - almost like some sort of electrical glitch or issue.  Thats a lot of generally unrelated things erroring at once for a period of time.

Two things, are there any radio masts at all anywhere near there?  Is it possible something actually hit it (like a bird?)

2018-8-24
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hugoleveille
lvl.3
Flight distance : 370174 ft
Canada
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There is a cell tower 500m away from takeoff site (3km from problem site). Else, a pure empty field.

When this happened, it was almost a copy paste of the same kind of problem I has a month ago in a completely different location (again, empty field just after water). In this other flight, the same thing triggered the problem. I was flying straight for 1.5km then started a small turn to start a comeback. Then drone looked like it wanted to fall from sky and returning home, the drone looked like it was drifting.

Here is a clip of that event:

And the log of that:
https://www.phantomhelp.com/logviewer/1VT1ZDF59ZK3LA2JH3A5/

After the first I was worried but tomd myself it was a isolated event. But with the new one, I am very worried. Did a test flight this morning and everything was rock solid. But it requested a compass calibration.

Again, thank you all for the help
2018-8-24
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Lonesome Crow
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gnirtS Posted at 2018-8-24 02:56
Im having issues loading the text file into the analysis program ( @jjbspark ).
But from the logs yes theres a sporadic wind warning but nothing to be worried about.

Same question, possible bird?
2018-8-24
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hugoleveille
lvl.3
Flight distance : 370174 ft
Canada
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I don’t think so. And since the 2 events look so much the same, i doubt that I hit 2 birds on 2 different flights when in both case I started a slight turn

Thanks

2018-8-24
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G_Sig
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Iceland
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hugoleveille Posted at 2018-8-24 03:56
There is a cell tower 500m away from takeoff site (3km from problem site). Else, a pure empty field.

When this happened, it was almost a copy paste of the same kind of problem I has a month ago in a completely different location (again, empty field just after water). In this other flight, the same thing triggered the problem. I was flying straight for 1.5km then started a small turn to start a comeback. Then drone looked like it wanted to fall from sky and returning home, the drone looked like it was drifting.

Look at player under Notifications then you can play your flight back and see the error messages.
High wind is the reason for most of this. Over 30 km/h is rather strong.https://app.airdata.com/share/XDJfuU

2018-8-24
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gnirtS
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G_Sig Posted at 2018-8-24 05:28
Look at player under Notifications then you can play your flight back and see the error messages.
High wind is the reason for most of this. Over 30 km/h is rather strong.https://app.airdata.com/share/XDJfuU

Ive got my doubts over the AirData wind algorithm at times in higher winds (based on my MP experience as well).
Looking at his logs the drone is pitched maybe 15 degrees to maintain a position.  Thats enough to trigger the level 1 wind warning (which is in the logs) but not enough to trigger the level 2 warning.

A 30km/h wind would be way over a level 2 but the aircraft pitch doesn't really tally with that.

Its possible it got hit by a gust or thermal but the logs arent really telling that story clearly to me anyway.
2018-8-24
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hugoleveille
lvl.3
Flight distance : 370174 ft
Canada
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Didn’t feel wind was an issue. Trees are pretty still. I have opened a ticket with DJI to see what they think

Is the log from the first flight also yields  a wind problem? Cause it was the same problem
2018-8-24
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G_Sig
Captain
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hugoleveille Posted at 2018-8-24 06:35
Didn’t feel wind was an issue. Trees are pretty still. I have opened a ticket with DJI to see what they think

Is the log from the first flight also yields  a wind problem? Cause it was the same problem

This is the log from the first flight.
2018-8-24
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gnirtS
Captain
Flight distance : 2993497 ft
United Kingdom
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The .DAT file on the drone itself might be of more use (and DJI assistant to look at it).
That'll have raw sensor data and so on.
2018-8-24
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Dalford
Second Officer
Flight distance : 445367 ft
United States
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I had the same type of issue that I reported several weeks ago...  https://forum.dji.com/thread-159864-1-1.html

Here is a short clip when it acted up, looks very familiar to the others above, same type circumstances, straight line about 3700 feet...

2018-8-24
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hugoleveille
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Flight distance : 370174 ft
Canada
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Dalford Posted at 2018-8-24 06:53
I had the same type of issue that I reported several weeks ago...  https://forum.dji.com/thread-159864-1-1.html

Here is a short clip when it acted up, looks very familiar to the others above, same type circumstances, straight line about 3700 feet...

Wow, looks like the exact same problem. Scary
2018-8-24
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dont slow down
Second Officer
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United States
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Clearly the IMU failed. It switched to the backup multiple times. Also if you look at the log at min 11 22.8 sec the IMU altitude switches to a negative value as it appears he was still returning. My guess is some glitch caused the IMU to fail and since the drone was in motion it didn't reset correctly, which caused it to fail again.
2018-8-24
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Pete 456
lvl.1
United Kingdom
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I had exactly the same happen two weeks ago, IMU Failure - switched to back-up, since then many issues with drifting, failure to fly even in a straight line, gimbal failing to hold horizon, etc. Seems to just et worse - DJI have now accepted return for investigation. Afraid it seems that once you get an IMU failure it impacts on other functions (in my experience and from seeing other posts on same issue). They will tell you to re-set through the Assistant, recalibrate, etc, etc but you're probably looking a return.....
2018-8-24
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Steve F
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hugoleveille Posted at 2018-8-24 06:35
Didn’t feel wind was an issue. Trees are pretty still. I have opened a ticket with DJI to see what they think

Is the log from the first flight also yields  a wind problem? Cause it was the same problem

Looking at the video toward the end as you are trying to bring it end, those trees are really moving. The MA is trying to counter this with quite a bit of yaw.  Seems like a wind issue to me.
2018-8-24
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Sunset Gigolo
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Flight distance : 6339 ft
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I think that you were to close to the highway and someone with a CB Radio  keyed there mic , that will do it every time especially if they have a kicker installed  on it
2018-8-24
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Dalford
Second Officer
Flight distance : 445367 ft
United States
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Sunset Gigolo Posted at 2018-8-24 08:41
I think that you were to close to the highway and someone with a CB Radio  keyed there mic , that will do it every time especially if they have a kicker installed  on it

I assume you are speaking of my issue (dalford).  I’m hoping it is some random RF interference.  I’m pretty wary now when I fly. I also went to the area where it malfunctioned and did notice high voltage wires strung on top of large isolators.  I know on the beachside the power lines arc due to salt buildup on the isolators.  The power company sometimes comes along and spray water to clean off the salt.  My hope is there was some arcing going on that caused my issue.  Don’t know as I can’t see any in the daylight or at night at that location but does not mean some low level arcing is happening.

I have flown this drone for over 4 months, close to power lines even.  Got interference warnings but nothing like this.

It seems the common thread to most is flying an extended distance away in a straight line at a constant speed.  Just wondering if there is an overheating issue with the drone electronic board and IMU.

When the weather is good, I’m going to try again but alter my course away from the power lines.
2018-8-24
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rwynant V1
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Dalford Posted at 2018-8-24 09:26
I assume you are speaking of my issue (dalford).  I’m hoping it is some random RF interference.  I’m pretty wary now when I fly. I also went to the area where it malfunctioned and did notice high voltage wires strung on top of large isolators.  I know on the beachside the power lines arc due to salt buildup on the isolators.  The power company sometimes comes along and spray water to clean off the salt.  My hope is there was some arcing going on that caused my issue.  Don’t know as I can’t see any in the daylight or at night at that location but does not mean some low level arcing is happening.

I have flown this drone for over 4 months, close to power lines even.  Got interference warnings but nothing like this.

You could have been bouncing off a DJI GEO NFZ considering it "appears" you were flying in Class B airspace.

Post where you were at, and I'll look it up.......

Randy

2018-8-24
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Dalford
Second Officer
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Actually, I am close to a class D airport... I believe if you try to fly into a NFZ  your drone will stop moving forward, not fall out of the sky.  I could be wrong though...lol.
2018-8-24
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hugoleveille
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Canada
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Dalford Posted at 2018-8-24 13:09
Actually, I am close to a class D airport... I believe if you try to fly into a NFZ  your drone will stop moving forward, not fall out of the sky.  I could be wrong though...lol.

When your problem arrived, were you starting a turn after the long stretch? Cause in both occasion, everything felt apart after starting a slight turn after minutes of straight line
2018-8-24
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MrArcher
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dont slow down Posted at 2018-8-24 07:48
Clearly the IMU failed. It switched to the backup multiple times. Also if you look at the log at min 11 22.8 sec the IMU altitude switches to a negative value as it appears he was still returning. My guess is some glitch caused the IMU to fail and since the drone was in motion it didn't reset correctly, which caused it to fail again.

x2 .................
2018-8-24
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Dalford
Second Officer
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hugoleveille Posted at 2018-8-24 15:04
When your problem arrived, were you starting a turn after the long stretch? Cause in both occasion, everything felt apart after starting a slight turn after minutes of straight line

No, there was a jerk to the left by the MA but not due to anything I did. I think it went to atti mode and started drifting left and backwards before all the gyrations....
2018-8-24
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bjr981s
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I concur with most of the comments here. One thing I did notice was at the time you had these issues you flew from above trees to an open area. I suspect that the wind strength was higher here due to no tree interference with the air flow.

I think you can trigger the IMU fault if you have too much tilt on the drone in the wind.

Also risky business flying that low at that distance. The 2.4 and 5.8Ghz range is propagated by space waves not ground wares i.e. a direct line of sight is required. You would have had significant shadow due to the line of trees just in front of your flight path.

Nice video.

p.s. I have had issues flying my P4+ close to motorways and getting too close to cell towers. It just completely loses connection and initiates a RTH that takes a while to reestablish a connection.


2018-8-25
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JJBspark
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Hi hugoleveile,

Just had a look into your flight.

Don`t have the answers what happend, but found some 'strange' values for your heading.

After you had stopped that slow yaw turn to the left your heading did change after 1 second from steady 347 to 019 and back to 318 to 347. (last part when fwd pitch stopped).

Moment later you only pulled power and the hdg went from 350 > 016 > 347 > 030.

Ofcourse drone should keep his heading (within few degrees and correcting back) when only pictch and or power is the only input.

All this hdg excursion made the IMU think uh??  So switching to #2 and momentarily in ATTI.

Did this all happend due to the high wind? i do not know. Does it look like the sudden hdg twich some experience just after take off? Don`t think so.
At the same time some other values changed in your log ; an abnormal FAN state went TRUE and a HeighLimit status changed to a "avoid ground" status.

I would advice to let DJI check your flight log and DAT data of this flight to find out what is mayby wrong with your hardware.

Could it be mayby a hardware power quick fail in a internal component?
See my charts for the YAW excursions.

cheers
JJB
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2018-8-25
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gnirtS
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Flight distance : 2993497 ft
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Unrelated note - i couldnt get his flight look .txt off phantomhelp to load in your app.



And yes i tried renaming it and changing the path.
2018-8-25
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hugoleveille
lvl.3
Flight distance : 370174 ft
Canada
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Emailed support and got a fast but generic respond to recalibrate IMU and gimbal... Guess I will do that but not convinced
2018-8-25
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