My Mavic flew away at New Years Eve

[Mikenizm]

Hello all, my Mavic flew away from me with New Years Eve, it gave me a lot of errors and warnings and I haven't found it sinds then. Is there someone who could tell me what the hell happend with the Mavic?

At NYE I wanted to shoot some nice sky pictures from the fireworks in Amsterdam, but as soon as I got it in the air it started drifting and I got a lot of warnings. I tried to fly it back to me but it looked like it didn't react to all of my commands and eventually it lost connection.
I searched for it in the areas after the point it lost connection but didn't find it.

Airdata UAV - Flight Data Analysis for Drones

DJI Flight Log Viewer - PhantomHelp.com

 

[msinger]

what the **** happend with the Mavic?

You took off from a sidewalk. Most sidewalks (and other concrete structures) contain magnetic metal (rebar). That prevents the compass from working as designed -- which causes the Mavic to switch to ATTI mode and start drifting with the wind.

 

[ddodell]

You took off from a sidewalk. Most sidewalks (and other concrete structures) contain magnetic metal (rebar). That prevents the compass from working as designed -- which causes the Mavic to switch to ATTI mode and start drifting with the wind.

View attachment 28246

Being new to this and learning ... this makes sense ... but once it was away from the concrete / metal rebar, wouldn't the GPS mode kick in and enable more accurate control again?

 

[msinger]

once it was away from the concrete / metal rebar, wouldn't the GPS mode kick in and enable more accurate control again?

In most (all?) cases, you'd need to land, power off the Mavic, move it to a location where there are no nearby magnetic metal objects, and power it on again.

 

[ddodell]

In most (all?) cases, you'd need to land, power off the Mavic, move it to a location where there are no nearby magnetic metal objects, and power it on again.

Wow! Good to know ... Glad I learned not to make the assumption that it would kick into GPS mode once it got a clear view of the satellites.

 

[sar104]

Being new to this and learning ... this makes sense ... but once it was away from the concrete / metal rebar, wouldn't the GPS mode kick in and enable more accurate control again?

As @msinger said - that flight was doomed from the start. Firstly, the magnetic issues at the take off point led to to the aircraft abandoning P-GPS mode due to compass/yaw errors. Those occur when the inertial navigation system and the compass disagree on the aircraft heading, and if the disagreement persists and is severe enough the aircraft simply switches to ATTI mode. Secondly, you have 40 mph winds at 400 ft out of the SW - much too strong to be flying in.

In terms of where it ended up, if we assume that the aircraft lost uplink at the same time as downlink was lost, then it should have started to descend immediately. Projecting its descent path in that wind (likely an overestimate as the wind speed will decrease as it descends) indicates it would probably have come down around or just past the railway lines.

 

[Mikenizm]

You took off from a sidewalk. Most sidewalks (and other concrete structures) contain magnetic metal (rebar). That prevents the compass from working as designed -- which causes the Mavic to switch to ATTI mode and start drifting with the wind.

Aah didn't think about that, that's pretty stupid.

 

[Mikenizm]

As @msinger said - that flight was doomed from the start. Firstly, the magnetic issues at the take off point led to to the aircraft abandoning P-GPS mode due to compass/yaw errors. Those occur when the inertial navigation system and the compass disagree on the aircraft heading, and if the disagreement persists and is severe enough the aircraft simply switches to ATTI mode. Secondly, you have 40 mph winds at 400 ft out of the SW - much too strong to be flying in.

In terms of where it ended up, if we assume that the aircraft lost uplink at the same time as downlink was lost, then it should have started to descend immediately. Projecting its descent path in that wind (likely an overestimate as the wind speed will decrease as it descends) indicates it would probably have come down around or just past the railway lines.

Thanks, I checked that area before and after the railway lines but didn't find it. The railway lines are off limits so I cannot look over there unfortunately.

 

[ddodell]

In most (all?) cases, you'd need to land, power off the Mavic, move it to a location where there are no nearby magnetic metal objects, and power it on again.

Would their be any type of warning of compass interference before starting? Would it show the compass needed calibration or anything else like that? Or if the controller shows you're in GPS mode you're good to go?

 

[msinger]

Would their be any type of warning of compass interference before starting?

DJI GO sometimes shows a message and tells you to move the Mavic to another location. In other cases, no message is displayed (even though the compass is being affected).

Before taking off, look at the red aircraft symbol on the map in DJI GO. Make sure it's pointing in the correct direction and that it's not slowly spinning while the Mavic is sitting on the ground.

 

[ddodell]

DJI GO sometimes shows a message and tells you to move the Mavic to another location. In other cases, no message is displayed (even though the compass is being affected).

Before taking off, look at the red aircraft symbol on the map in DJI GO. Make sure it's pointing in the correct direction and that it's not slowly spinning while the Mavic is sitting on the ground.

And I also to assume if the red aircraft is NOT pointing in the correct direction, but not slowly spinning, that would also be a compass error?

 

[msinger]

That's correct. You should check for both of those things. Either is a sign of a problem.