Compass error

[Fufar Visual]

HI
I just had a crash with Mavic Air in a shipyard,because I suddenly got the message 'compass error' (or similar) and completely lost control as the Magic flew into a newly painted supertanker in the dock ( the subject for my filming). Unfortunately I forgot to mount the propeller guards so the drone fell to the bottom of the concrete dock from about 8 m. I had previously at the same shipyard in the bottom of the dry dock had to re calibrate the compass several times. Anyone with similar experiences and a possible solution for the future ? kr
Torben

 

[Mrmund]

I recently had a similar problem and an old wharf. What I finally did was to calibrate outside the property fly my Air and walk in(VLOS) and then took my shot. My guess is you never got a clean calibration so your compass was affected the whole time

 

[brett8883]

HI
I just had a crash with Mavic Air in a shipyard,because I suddenly got the message 'compass error' (or similar) and completely lost control as the Magic flew into a newly painted supertanker in the dock ( the subject for my filming). Unfortunately I forgot to mount the propeller guards so the drone fell to the bottom of the concrete dock from about 8 m. I had previously at the same shipyard in the bottom of the dry dock had to re calibrate the compass several times. Anyone with similar experiences and a possible solution for the future ? kr
Torben

I’m sorry you had this bad experience but it’s part of the learning process and you did the right thing by coming to the forum to get more information. I suspect the mass amount of metal in the ship affected the compass as you flew into it. The Mavic switched to Atti mode. In this mode the aircraft will level itself when you release the sticks instead of braking so it will continue in the current direction until you fly it in another direction or it loses inertia.

If you flew into the ship it also could just be that it lost GPS reception in which case it also will revert to Atti mode.

You have to be really careful when flying inside of a structure because of this and I would have advised not to do this until you you are a extremely experienced pilot because this is a very risky and complicated mission. This is also why it pays off to get practice flying in Atti mode so you will know how to fly if something like this happens unexpectedly.

I’m sorry this happened. In the future if you plan to fly in an unusual location like this you are welcome to ask the forum if we suspect there might be an issue and we’d be happy to give you advice on how to do it safely or give you heads up about the potential problems you might encounter. In this case I would have advised to maintain distance from the vessel or to turn on the mavic and carry it along the flight route to see if the ship itself would mess with the instruments. When you carried it into the ship it would have given you a magnetic interference warning or let you know that there was an issue with gps inside the vessel.

It’s just a matter of experience and now you are better informed and will be able to take this experience and are a better pilot for it.

Let me know if you have any other questions

 

[Meta4]

I just had a crash with Mavic Air in a shipyard,because I suddenly got the message 'compass error' (or similar) and completely lost control as the Magic flew into a newly painted supertanker in the dock ( the subject for my filming). Unfortunately I forgot to mount the propeller guards so the drone fell to the bottom of the concrete dock from about 8 m. I had previously at the same shipyard in the bottom of the dry dock had to re calibrate the compass several times. Anyone with similar experiences and a possible solution for the future ?

The steel in the ship did not cause the problem at all and there was probably no problem with GPS either..
The problem was that you launched from very close to enough steel to cause a yaw error.
When you powered up and the compass was initiating, the magnetic field form some nearby steel caused the compass to get an incorrect setting for north.
The most likely cause was launching from reinforced concrete (the steel reinforcing in the concrete causes the problem).
Once your Mavic launched and left the magnetic field that caused the problem, it's compass was now reading incorrectly and confusing the flight controller.
It tries to correct but because of the incorrect compass data each correction makes things worse.

Launching from a steel or reinforced concrete is something you should always avoid.

 

[Meta4]

You start by saying the steel in the ship didn’t cause the problem but then go on to say the steel in the ship was the problem... ?

That's not what I said at all - read it again.
The OP wasn't launching from onboard the ship, he was in a shipyard and most of the area available for launching would have been reinforced concrete.

Flying close enough to a large steel object to get a warning of magnetic interference doesn't cause the drone to fly off uncontrollably.
Try it yourself sometime by descending toward a steel roof.
As you get closer, maybe 6 feet or so above the roof, you'll see the drone start to wander a little or slowly spiral.
That's the compass being affected by the magnetic field in the steel interfering with the compass reading of the earth's normal field.
Lift the drone a few feet higher and it hovers properly, lower it and you see the effect.
But the drone won't zoom off on a kamikaze flight as it often does when launching from reinforced concrete causes a yaw error.

 

[brett8883]

That's not what I said at all - read it again.

Flying close enough to a large steel object to get a warning of magnetic interference doesn't cause the drone to fly off uncontrollable.
Try it yourself sometime by descending toward a steel roof.
As you get closer, maybe 6 feet or so above the roof, you'll see the drone start to wander a little or slowly spiral.
That's the compass being affected by the magnetic field in the steel interfering with the compass reading of the earth's normal field.
Lift the drone a few feet higher and it hovers properly, lower it and you see the effect.
But the drone won't zoom off on a kamikaze flight as it often does when launching from reinforced concrete causes a yaw error.

I reread the mesaage and deleted my original my message because I did in fact read it wrong.

However I just don’t see there being enough information to support your conclusion. What I heard was the Mavic was flying normally until it flew inside of a ship which is presumably all steel. When surrounded on all sides by a magnetic field will most certainly cause a compass error and is different from flying close to a roof.

We both agree this is metal related but why you think that flying inside of an all metal ship would not cause a compass error or for it to lose GPS I don’t quite understand. That seems like a certainty. Either of those things will cause an error that will most certainly cause it to switch the Atti mode and for someone not expecting this or understanding Atti mode yea it could seem like it’s flying off on its own.

 

[sar104]

Rather than speculate about the cause, I suggest that the OP retrieves and posts the mobile device DAT file for the flight. That will show unambiguously what happened.

 

[Meta4]

However I just don’t see there being enough information to support your conclusion.

I've seen many, many incidents just like this and have a pretty good idea what happened.

What I heard was the Mavic was flying normally until it flew inside of a ship which is presumably all steel. ..
We both agree this is metal related but why you think that flying inside of an all metal ship would not cause a compass error or for it to lose GPS I don’t quite understand. That seems like a certainty. Either of those things will cause an error that will most certainly cause it to switch the Atti mode and for someone not expecting this or understanding Atti mode yea it could seem like it’s flying off on its own

The OP didn't say he flew inside the ship.
His words were the Mavic flew into a newly painted supertanker in the dock .
He almost certainly meant the Mavic flew into (the side of) a newly painted supertanker in the dock .
Tankers don't have a lot of entry points where you could fly inside.
But they do have very large hulls that present a hard-to-miss target for a runaway drone to slam into.
Further confirmation was when he said that the drone fell down into the bottom of the dry dock, which wouldn't have happened if he was flying inside the ship.

To help you visualise ... this is the sort of vessel he was talking about:

 

[Former Member]

I've seen many, many incidents just like this and have a pretty good idea what happened.


The OP didn't say he flew inside the ship.
His words were the Mavic flew into a newly painted supertanker in the dock .
He almost certainly meant the Mavic flew into (the side of) a newly painted supertanker in the dock .
Tankers don't have a lot of entry points where you could fly inside.
But they do have very large hulls that present a hard-to-miss target for a runaway drone to slam into.
Further confirmation was when he said that the drone fell down into the bottom of the dry dock, which wouldn't have happened if he was flying inside the ship.

To help you visualise ... this is the sort of vessel he was talking about:

 

[Meta4]

What does that mean?

 

[Former Member]

What does that mean?

Oh sorry, just testing out the new emoticons.

Carry on.

 

[brett8883]

I've seen many, many incidents just like this and have a pretty good idea what happened.


The OP didn't say he flew inside the ship.
His words were the Mavic flew into a newly painted supertanker in the dock .
He almost certainly meant the Mavic flew into (the side of) a newly painted supertanker in the dock .
Tankers don't have a lot of entry points where you could fly inside.
But they do have very large hulls that present a hard-to-miss target for a runaway drone to slam into.
Further confirmation was when he said that the drone fell down into the bottom of the dry dock, which wouldn't have happened if he was flying inside the ship.

To help you visualise ... this is the sort of vessel he was talking about:

So just to be clear you don’t think that a thousand tons of steel nearby had nothing to do with a compass error?

 

[Meta4]

So just to be clear you don’t think that a thousand tons of steel nearby had nothing to do with a compass error?

It's probably more like 100,000 tons and I don't think it had anything to do with the issue described.
My main drone photo subject is ships.
I've photographed hundreds of them and never had any compass issues doing it.

As I mentioned earlier, getting close to a steel object in flight won't make the drone zoom away uncontrollably.
But launching from a magnetically influenced area will and we see reports of that kind of incident every week here.

 

[brett8883]

It's probably more like 100,000 tons and I don't think it had anything to do with the issue described.
My main drone photo subject is ships.
I've photographed hundreds of them and never had any compass issues doing it.

As I mentioned earlier, getting close to a steel object in flight won't make the drone zoom away uncontrollably.
But launching from a magnetically influenced area will and we see reports of that kind of incident every week here.

Hah I did look everywhere to find the tonnage of a ship like that and it was so difficult! They only classify them in DWT! I figured the point would get across anyway if I went on the way low end of it.

I forgot you have a lot of experience flying from these ships so I defer that point to you it’s just hard to believe that wasn’t a major factor.

@Fufar Visual do you know how to upload a dat file for us?

 

[sar104]

Hah I did look everywhere to find the tonnage of a ship like that and it was so difficult! They only classify them in DWT! I figured the point would get across anyway if I went on the way low end of it.

I forgot you have a lot of experience flying from these ships so I defer that point to you it’s just hard to believe that wasn’t a major factor.

@Fufar Visual do you know how to upload a dat file for us?

It's going to depend a lot on just how close you get. @Meta4's photos (at least the ones that I've seen) are taken from far enough away to get the entire vessel in the field of view. At that distance I wouldn't expect any magnetic interference. On the other hand, if one launched from a pier and flew close to the ship then that's a different matter - it might well interfere enough to cause flight issues or even a switch to ATTI mode. We have seen at least one case of that here recently caused by flying close to a steel bridge.

 

[Mrmund]

The OP didn't say he flew inside the ship.
His words were the Mavic flew into a newly painted supertanker in the dock .
He almost certainly meant the Mavic flew into (the side of) a newly painted supertanker in the dock .
Tankers don't have a lot of entry points where you could fly inside.
But they do have very large hulls that present a hard-to-miss target for a runaway drone to slam into.
Further confirmation was when he said that the drone fell down into the bottom of the dry dock, which wouldn't have happened if he was flying inside the ship.

To help you visualise ... this is the sort of vessel he was talking about:

[/QUOTE]
Great shot! yours?

 

[Mrmund]

I could be mistaken but from my experience and what I've read here this doesn't sound like an issue with GPS at all.
Sounds like the compass was disagreeing with the IMU.
I'm always willing to learn so Fufar please post your mobile device DAT file for the flight like Sar104 suggested

 

[Meta4]

Great shot! yours?

Thanks ... yes

 

[Fufar Visual]

Appreciate the interest in 'my' problem ! I never uploaded a dat file, but if that can help to define a 'diagnosis' can someone tell me how to upload ?

 

[sar104]

Appreciate the interest in 'my' problem ! I never uploaded a dat file, but if that can help to define a 'diagnosis' can someone tell me how to upload ?

Mobile device DAT file: How to retrieve a V3.DAT from the tablet