Cranky Mavic crashed.

[SKY808]

Never had any problems with my Mavic Pro 1.

Recently I placed the Mavic on a 4 foot diameter metal garden table to take off from. I figured its profile and shape would bode well with terrain recognition on the landing.

Did all the checks. As I took off to 5 feet, it flew starboard at an angle, uncontrollably, and I instinctively tried to counter this, then as it wouldn't react, pulled the joystick down to force land. However it had already hit a garden umbrella and fell to the concrete.

I repeated the flight from grass and all went well other than it reporting 'unexpected gimble vibration' and the picture was wavy and distorted. I thought it might have buckled a prop (they looked fine). I checked this forum and it appears the gimble needed to re-clip behind a black plastic lug on the inside of the body cavity as it had unseated in the fall.

It worked thereafter (had to replace a prop with slight split)

I guess the metal interfered with the signals / checks? We live and learn.

 

[Meta4]

I guess the metal interfered with the signals / checks? We live and learn.

"Metal" is no problem. Steel is a big problem.
Never launch from a steel or reinforced concrete surface.

 

[Moose1967]

Did you have GPS lock before you took off ??

 

[4wd]

The compass was messed up, I'm surprised the app didn't tell you.
If you look at the (app) arrow indicating the direction it thinks it is pointing, that needs to check out with reality.

 

[Meta4]

Did you have GPS lock before you took off ??

Launching prematurely wouldn't have caused incident as described.
However, yaw error caused by launching from a steel surface will.

 

[Koelkop]

Do not take off from anything magnetic, the app does not always warn you before takeoff that the compasses is faulty.

I have had it happen to me after i took off from a vehicle. Nothing showed wrong but a minute into the flight it went into atti mode.

 

[sar104]

The Mavic 2 has firmware that appears to detect and correct for magnetic distortion at takeoff, but the Mavic Pro does not do that and it will cause a yaw error. If the FC switches to ATTI mode then the flight will be stable but with no position hold. However, the FC often doesn't switch fast enough, and if it continues to operate in P-GPS mode then, depending on the magnitude of the yaw error, the result can be uncontrolled flight as described above.

 

[SKY808]

Two things

Thanks for replying and it will help other too hopefully

Safe and happy flying.

On a side note my business recently had a theft of iMac computers in Essex (£7k worth). We had CCTV with good images of car and thieves, drugs dropped at scene but Police said they will not send an officer out to investigate. The BBC contacted them and they then said they would. They didn't and therefore have lied. It's their policy now it seems and a freedom of information act search notes this tens of thousands of times in Essex.

An upside?

It's a scandal, but I guess this means the Police will never come out to a report of a drone flying over a garden or 1m too high or low? It must give us responsible flyers more confidence to not worry unduly?

 

[berisen]

The Mavic 2 has firmware that appears to detect and correct for magnetic distortion at takeoff, but the Mavic Pro does not do that and it will cause a yaw error. If the FC switches to ATTI mode then the flight will be stable but with no position hold. However, the FC often doesn't switch fast enough, and if it continues to operate in P-GPS mode then, depending on the magnitude of the yaw error, the result can be uncontrolled flight as described above.

Do you know it is possible in terms of hardware of having the same detection/correction on the MP as well? It would sure feel a lot safer to have that function since it's hard to tell if there's any magnetic interference nearby or not. If possible, then maybe we can hope for a FW update on the MP in the future.

 

[sar104]

Do you know it is possible in terms of hardware of having the same detection/correction on the MP as well? It would sure feel a lot safer to have that function since it's hard to tell if there's any magnetic interference nearby or not. If possible, then maybe we can hope for a FW update on the MP in the future.

It's implemented as a computational process to check for a change in magnetic yaw on takeoff, so presumably it could be added to any DJI aircraft firmware.

As for checking for interference – that's actually really simple – just ensure that the aircraft orientation arrow in the map agrees with the direction that the aircraft is facing. If it is correct then there is no magnetic interference that matters. If it isn't then move the aircraft.