So today like almost everyday I was out flying my M2P. Spot I've flown a ton of times. Started the drone and lifted off..All things normal. Then all hell broke loose.  The drone turned sideways and took off in the opposite direction I wanted to go. I immediately tried to recover to no avail. Seeing how low I was I then raised altitude to clear wires and houses and it did rise. Then I let go of sticks and the thing was rocketing away. I then hit the RETURN HOME button but it kept going away. Thinking the worst I was ready to get in my car to try and head the direction it was going. Then I noticed it was returning home. It did return home and land normally.

Looking at this log       https://www.phantomhelp.com/LogViewer/Z8Q0W1YLVJKPVRJCGG74

Few things are weird.

1. Why is it sideways on the flyaway?

2. Why when hitting home button did it turn and face home but still speed away in the opposite direction?

3.  Did it really hit 70+ miles per hour. I thought it was going fast but that sounds insane. I did see something on screen I never saw before about max speed...


Any idea what happened here.

Any idea what happened here.
Unfortunately you were flying with Litchi and Litchi logs are a pain to try to read.
But the description of the incident fits a yaw error situation perfectly.
You were very lucky to get the drone back again.
Most yaw error incidents end a lot worse than that.
The usual cause is launching from a magnetically compromised spot.
What was the launch surface?

1. Why is it sideways on the flyaway?
It's complicated to explain but that's what happens in a yaw error situation.

2. Why when hitting home button did it turn and face home but still speed away in the opposite direction?
Because it couldn't stop and hold position.
It was trying to correct for movement but because of the yaw induced at startup, any correction it made was wrong which made it correct more etc, etc.

3.  Did it really hit 70+ miles per hour. I thought it was going fast  but that sounds insane. I did see something on screen I never saw before  about max speed...
Possibly .. Yaw errors often involve very fast uncontrollable flight as the drone attempts to correct, but it cannot.

Well the answer to the launch site there is a big generator nearby that powers a pump that sends drain water into the river. It comes on and off as water fills. As I mentioned I've flown there many times with no issues but it's quite possible it was a magnetic situation or at the least can't eliminate that. Aside from interference is there anyway to avoid yaw error? I've flown over 1400 flights and never seen this before. As for speed I didn't realize the drones could go that fast and wondering why they cap the speed much lower. Thanks for your help.

One thing I noticed in Air Data is this GPS situation. Would this be GPS related? Looks like the return home started around the time the GPS corrected. I do have a Firehouse light on top of the drone but hasn't been an issue before.

BrianKushner Posted at 4-5 18:43
Well the answer to the launch site there is a big generator nearby that powers a pump that sends drain water into the river. It comes on and off as water fills. As I mentioned I've flown there many times with no issues but it's quite possible it was a magnetic situation or at the least can't eliminate that. Aside from interference is there anyway to avoid yaw error? I've flown over 1400 flights and never seen this before. As for speed I didn't realize the drones could go that fast and wondering why they cap the speed much lower. Thanks for your help.

Well the answer to the launch site there is a big generator nearby that powers a pump that sends drain water into the river. It comes on and off as water fills. As I mentioned I've flown there many times with no issues
I was more interested in the surface you placed the Mavic on to power up and launch from.
Unless the generator is within just a few feet, it's not likely to have caused any problem.
Launching from reinforced concrete surfaces is the most common cause of yaw error incidents.
In those cases, having launched from there before doesn't prove teh surface is safe.
It can be a matter of just an inch or two with the placement of teh drone relative to some part the invisible reinforcing mesh that causes the issue.


One thing I noticed in Air Data is this GPS situation. Would this be GPS related?
No .. your GPS looks fine and having a less than ideal number of sats doesn't make a drone do what yours did.
It will be that it was initialised within a magnetic field that caused it to have a false idea of where north was.

I launched from a plastic box I always use  which is about 2+ feet off the ground which was on the grass..However there is a good chance where I launched from there would be a giant metal pipe under the surface?

BrianKushner Posted at 4-5 19:10
I launched from a plastic box I always use  which is about 2+ feet off the ground which was on the grass..However there is a good chance where I launched from there would be a giant metal pipe under the surface?

OK .. on a box about 2ft above concrete should prevent issues with simple reinforcing mesh.
The issue happens when the drone is initialised within a weak magnetic field.
If it's strong, the drone will warn with a compass error and won't launch.
But if the field isn't strong enough to set off a compass error but is strong enough to cause the mag yaw to initialise incorrectly, that causes the issue.
A large steel pipe at the right distance could possibly cause the problem.

Thanks again for looking at this. Hope it never happens again. I thought the drone was a goner...and a note for DJI give us 75mph :-)

It sounds like the temporary IMU/Yaw disagree issue thats hit some M2s (mine included) on some flights then recovers.
It thinks its pointing and heading 90 degrees away from actual, tries to correct, thinks its even more off course, corrects even more etc.  Thats how you can get huge speeds too.

Sadly with Litchi i dont think you can access the full, complete logs needed for someone to see the actual cause.

gnirtS Posted at 4-5 21:49
It sounds like the temporary IMU/Yaw disagree issue thats hit some M2s (mine included) on some flights then recovers.
It thinks its pointing and heading 90 degrees away from actual, tries to correct, thinks its even more off course, corrects even more etc.  Thats how you can get huge speeds too.

Yeah the 90 degree angle was weird as was the speed. So then these drones can do 75? That's 30 over current sport mode speed. Did you recover your bird from this?

Hi BrianKushner, for fly safety considering, you are recommended to use the DJI official app to fly the drone. If the issue persists, you may contact our support at the link below to open a case and send the drone in for a thorough diagnosis. Thanks.
http://www.dji.com/support

BrianKushner Posted at 4-5 21:58
Yeah the 90 degree angle was weird as was the speed. So then these drones can do 75? That's 30 over current sport mode speed. Did you recover your bird from this?

Well the normal speed limit is GPS and/or pitch depending on conditions.  But in the cases like this when the drone thinks its countering a knock or wind it doesnt apply.

Mine recovered after about 60 seconds (i posted about 14 months ago with video and logs).
Short summary, all fine for first 4-5 minutes of a flight, no winds, remote area.  Then without warning it started flying full power 90 degrees left of nose angle.  No matter which way you pointed the noise it was always 90 degrees left (so not wind).
I managed to circle it for a minute to formulate a plan but then it stopped as suddenly as it started and i was able to recover it normally.

The logs showed a sudden IMU/Yaw disagree (NOT compass) by 90 degrees and this continued and fixed itself again with no warning.  At no time were any IMU/ATTI/Compass errors reported.  Strong wind was reported presumably as it took the fake 90 degree drift as a wind.  There was no wind in reality.

There have been a few cases with the same issue and mine only did it *once* to date.

This may not be the case with yours but it appears at least similar.  Without the .dat logs though we cant tell.

gnirtS Posted at 4-5 21:49
It sounds like the temporary IMU/Yaw disagree issue thats hit some M2s (mine included) on some flights then recovers.
It thinks its pointing and heading 90 degrees away from actual, tries to correct, thinks its even more off course, corrects even more etc.  Thats how you can get huge speeds too.

Litchi logs can be retrieved on Airdata . Not sure how good they are though.

hallmark007 Posted at 4-6 06:32
Litchi logs can be retrieved on Airdata . Not sure how good they are though.

Litchi creates its own CSV log and a standard DJI TXT log in a separate directory, they aren't as comprehensive as the DJI TXT log, let alone the DJI DAT log though.

No DAT file i created with Litchi, which is necessary to get hold of the sensor data ... in this case the magYaw (compass direction).

The Litchi log files can be retrieved here:

On iOS devices:
The Litchi CSV logs are in Litchi » Documents » flightlogs, and the DJI TXT logs are in Litchi » Documents » SDK_logs » FlightRecord.​
​
On Android devices:
The Litchi CSV logs are in LitchiApp » flightlogs, and the DJI TXT log is stored in a subdirectory in the DJI app directory, DJI » com.aryuthere.visionplus » FlightRecord.​

slup Posted at 4-6 12:12
Litchi creates its own CSV log and a standard DJI TXT log in a separate directory, they aren't as comprehensive as the DJI TXT log, let alone the DJI DAT log though.

No DAT file i created with Litchi, which is necessary to get hold of the sensor data ... in this case the magYaw (compass direction).

Honestly I have never seen them, but it’s as I thought it would be, thanks for that.

DJI Natalia Posted at 4-6 02:10
Hi BrianKushner, for fly safety considering, you are recommended to use the DJI official app to fly the drone. If the issue persists, you may contact our support at the link below to open a case and send the drone in for a thorough diagnosis. Thanks.
http://www.dji.com/support

I would fly the DJI  app if you added VR to the app. Is there a reason DJI has never given this other then they want to sell goggles?

BrianKushner Posted at 4-5 21:58
Yeah the 90 degree angle was weird as was the speed. So then these drones can do 75? That's 30 over current sport mode speed. Did you recover your bird from this?

My Spark speed record is 85 mph..
In Atti mode, obviously a gps glitch..

BrianKushner Posted at 4-6 21:17
I would fly the DJI  app if you added VR to the app. Is there a reason DJI has never given this other then they want to sell goggles?

Hi there, I'd like to forward your request to the related team, however, you are not recommended to use the third party app, it may void your warranty. Thanks for your kind understanding.

Labroides Posted at 4-5 19:23
OK .. on a box about 2ft above concrete should prevent issues with simple reinforcing mesh.
The issue happens when the drone is initialised within a weak magnetic field.
If it's strong, the drone will warn with a compass error and won't launch.

Hi: I was just reading your responses to the problem that happened.  I learned a while back about magnetic issues when launching a drone but the assistance you provided to this topic is outstanding.  You took the time to provide detailed but simple answers to his questions.  Bravo!

I had this happen to me once a few years ago and it was after I had taken of from the ROOF of my CAR !    Lesson learned don't take of from the ground , I generally always take of holding the Drone and I've never had any issues since.