Max distance reached error then could only control altitude over water on a yacht! Saved by fishermen!

[BigL]

Yesterday I launched from a yacht in what I thought in the moment was ATTI mode. Everything was fine for about 8minutes, capturing various angles of the yacht, the wind was relatively light and no hassles. Suddenly I get a maximum distance warning of 1000m Distance but I can clearly see my Mavic and there's no way she's 1000m away from me. Must have been about 200m if that. I can only gain and lose altitude and rotate left and right. No movement with my right toggle at all. The yachts a deep hull and the skipper deemed it impossible to get under the unit to land. My battery is on 55% which gives me about another 10minute or so and I'm literally going into panic mode. I select the return to home option (which I have never used before 7years flying with 2 fatal crashes under my belt) I'm prompted which location to choose Current or Home point. I select current of course as the yacht has been moving. She climbs to the set height but then starts moving in the complete opposite direction! My battery is now at 40%. I cancel return home and for what seems like 20secs I have control and horizontal movement. At full tilt I'm trying to get her back to the now stationary yacht. Then again maximum distance warning and no horizontal plane! The battery warning is prompted and I am certain it's all over until a passing speedboat carrying fishermen starts approaching. I wave them down and beg to get me onto the bank under the unit to land. They react right away, I hop on board and speed out to where she is just hanging there, get under her and manage to catch land her with 25% battery with probably another 5mins flight time at a push to play with. No lies. I return to the yacht sat down and had to drink a glass of whiskey to calm down!

Clear what happened. The home point was fixed (GPS mode) and was measuring the distance from that point, as we kept sailing that distance increased hence the maximum distance reached. BUT what is strange is losing horizontal gain and also that as we headed back towards the home point the distance did not decrease.

Has anyone experience anything similar?

Flight record only shows (Weak GPS) But shows connected to 18 satellites.

The screenshot (if you look closely) Depicts me with the skipper waving the speedboat with fishermen onboard down. I cant attached the video to this file but.... Gives you an idea of the panic. hehehe

 

[Thomas B]

Welcome to the forum from the deserts of Arizona! Enjoy.

Is this a new drone?
What kind?
What kind of controller?
Can you post your log for the flight?

here’s a link that may help you to obtain and post the logs for the flight so it can be analyzed.

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

 

[Meta4]

Suddenly I get a maximum distance warning of 1000m Distance but I can clearly see my Mavic and there's no way she's 1000m away from me. Must have been about 200m if that.

The reason for that was that you launched from a moving boat which sailed or drifted well away from where the drone was launched.
The distance shows was the distance from the recorded home point, not distance from where you had moved to.
Setting a max distance when you are moving further than your distance limit is one way to lose your drone.
You were lucky to find help this time.

There are a couple of possibilities for the other things you mentioned but it will require the flight data to confirm.
Post the .txt file or follow the link in post #2 and post a link to the report that gives you and someone will work out what happened.

 

[BigL]

Thanks Thomas.
No been flying it for almost 1,2years now. MavicPRO, standard remote with flymore combo.
What I should have done was change the maximum distance in app while in flight but in the Log I pick ups YAW Error which doenst make sense, also the log is not picking up exactly where I moved while on the yacht.

DJI Flight Log Viewer | Phantom Help

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www.phantomhelp.com

Again thanks alot for your prompt response. Cant believe how lucky I was. heheheh

Welcome to the forum from the deserts of Arizona! Enjoy.

Is this a new drone?
What kind?
What kind of controller?
Can you post your log for the flight?

here’s a link that may help you to obtain and post the logs for the flight so it can be analyzed.

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

 

[BigL]

The reason for that was that you launched from a moving boat which sailed or drifted well away from where the drone was launched.
The distance shows was the distance from the recorded home point, not distance from where you had moved to.
Setting a max distance when you are moving further than your distance limit is one way to lose your drone.
You were lucky to find help this time.

There are a couple of possibilities for the other things you mentioned but it will require the flight data to confirm.
Post the .txt file or follow the link in post #2 and post a link to the report that gives you and someone will work out what happened.

Thanks Meta 4. Yeah i know that much is clear but quite strange picking up the YAW error and then compass error. Certainly not the first time iv flown from a moving object. Rally car, 4x4, speedboats, yachts, four-wheelers etc and im sure iv travelled just as far if not further... Quite possible that was flying without GPS though.....

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

 

[Meta4]

Thanks Meta 4. Yeah i know that much is clear but quite strange picking up the YAW error and then compass error. Certainly not the first time iv flown from a moving object. Rally car, 4x4, speedboats, yachts, four-wheelers etc and im sure iv travelled just as far if not further... Quite possible that was flying without GPS though.....

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

The yaw error, compass error, atti mode and weak GPS messages are all part of yaw error problem which first showed up at 13:04.

A yaw error often ends in the loss of a drone but yours appears to have been just a small one.
A yaw error happens when the drone is launched from too close to something made of steel or perhaps a live electric cable.
The compass gets deflected toward the steel but the strength of the magnetic field is not strong enough to bring up a compass error, but its direction is different from the earth's normal magnetic field.

The gyro sensor in the IMU is initialised based on the incorrect compass reading.
After you launch and exit the magnetic field, if you turn the gyro disagrees with the compass data
and you get your yaw error.
That's followed by the drone dropping GPS and falling into atti mode and depending on the difference between the false compass reading and actual, the drone may zip away in an uncontrollable curved flight at high speed in the worst cases.
The drone detects that it is off course and is attempting to correct but each correction puts it further off course.
With a bad yaw error, it is flying at crazy speed within seconds.
Yours appears to have been a small yaw error and it was all over at 13:38.3.
Another compass error showed up at 13:32.6, possibly related but not enough to cause a problem.
Your yaw error is a little puzzling in that it took so long to show up.
The usual cause is launching from very close to steel items, perhaps something under the deck etc?

From 13:29.5 you made a lot of efforts to control the drone and it looks like this is where you thought you could not move left/right.
The reason is that the drone was still in RTH and you were fighting against the drone trying to fly a straight line as programmed.

The Max Distance Limit was hit at 13:49.6 when 1000m from the home point.
You could have fixed this either by:
Going into the app settings and changing or cancelling the Max Distance Limit.
Or .. Resetting the homepoint to where the drone was at the time.

 

[boblui]

I select the return to home option .... I'm prompted which location to choose Current or Home point. I select current of course as the yacht has been moving. She climbs to the set height but then starts moving in the complete opposite direction!

That's because the home point location memorized by the craft was still the one where it took off from. Your selection of "current location" was not effective for some reasons.

... I cancel return home and for what seems like 20secs I have control and horizontal movement. At full tilt I'm trying to get her back to the now stationary yacht. Then again maximum distance warning and no horizontal plane! .....

At that point the craft was pointing to the yacht but it was still memorizing the old home point location from which the maximum distance has exceeded. Going towards the yacht would require it to move further away from the home point hence the craft did not respond to forward stick control or "no horizontal plane" in your language.

The problem could have been avoided by :

1) Not setting any distance limit
2) Keep updating the home point as the yacht moves.

 

[BigL]

The yaw error, compass error, atti mode and weak GPS messages are all part of yaw error problem which first showed up at 13:04.

A yaw error often ends in the loss of a drone but yours appears to have been just a small one.
A yaw error happens when the drone is launched from too close to something made of steel or perhaps a live electric cable.
The compass gets deflected toward the steel but the strength of the magnetic field is not strong enough to bring up a compass error, but its direction is different from the earth's normal magnetic field.

The gyro sensor in the IMU is initialised based on the incorrect compass reading.
After you launch and exit the magnetic field, if you turn the gyro disagrees with the compass data
and you get your yaw error.
That's followed by the drone dropping GPS and falling into atti mode and depending on the difference between the false compass reading and actual, the drone may zip away in an uncontrollable curved flight at high speed in the worst cases.
The drone detects that it is off course and is attempting to correct but each correction puts it further off course.
With a bad yaw error, it is flying at crazy speed within seconds.
Yours appears to have been a small yaw error and it was all over at 13:38.3.
Another compass error showed up at 13:32.6, possibly related but not enough to cause a problem.
Your yaw error is a little puzzling in that it took so long to show up.
The usual cause is launching from very close to steel items, perhaps something under the deck etc?

From 13:29.5 you made a lot of efforts to control the drone and it looks like this is where you thought you could not move left/right.
The reason is that the drone was still in RTH and you were fighting against the drone trying to fly a straight line as programmed.

The Max Distance Limit was hit at 13:49.6 when 1000m from the home point.
You could have fixed this either by:
Going into the app settings and changing or cancelling the Max Distance Limit.
Or .. Resetting the homepoint to where the drone was at the time.

Wow Meta 4, Thank you for your analysis. I have no doubt there was certainly a lot of magnetic inteference around the take-off at the stern of the yacht. I would say I got seriously lucky this time round without serious flyaways.
Yes thinking of it now that would have been the fix, adjusting the max distance limit or resetting the home point. In the moment it never came to mind. Again thanks for your time in analyzing the record. I seriously appreciate that. Il be on the same yacht this coming weekend.... Il let you know how it goes without any max distance limit and take off from the Bow this time or.... Possibly just from the bank of the lagoon rather!

 

[BigL]

That's because the home point location memorized by the craft was still the one where it took off from. Your selection of "current location" was not effective for some reasons.


At that point the craft was pointing to the yacht but it was still memorizing the old home point location from which the maximum distance has exceeded. Going towards the yacht would require it to move further away from the home point hence the craft did not respond to forward stick control or "no horizontal plane" in your language.

The problem could have been avoided by :

1) Not setting any distance limit
2) Keep updating the home point as the yacht moves.

Hey Boblui. Thank you kindly for your analysis. I got pritty lucky I would say but yes as per my comments to Meta4 at the time adjusting the max distance and updating the hompoint didn't come to mind. Il be on the yacht again this weekend...... Il keep you posted and yeah thanks for your input.