Mavic went ROGUE, and is gone

[Tone]

Sorry for your loss and many thanks for sharing so we can all learn - this has become a great thread!
I read previously in these forums about checking compass direction in the app is correct and have noticed mine 180° out 2 times in about 50 flights using the previous firmware (4 I think) with no warning popping up in the app. Moving position or calibrating fixed the issue.
I also had magnetic interference once on a big rock in the middle of nowhere, moved it 1m and all ok.

I always wait for good GPS lock before takeoff and move if needs be BUT...
I have been wondering what would happen if you took off in a deep valley for eg, in ATTI and the drone got a GPS lock in flight?
Even if compass and all was OK, would it still drift or toilet bowl a bit before it settled?
There's a few places like this with waterfalls I'd love to fly but without an ATTI mode switch I'm sensibly cautious.

 

[Lonjsnyder]

You should be okay.
For the first 30ft AGL, you will have downward facing VPS
Then as you ascend, you'll get eventually get GPS..

Here's a Phantom2 flying in ATTI from 5 stories below street level to then ascend & acquire GPS.

 

[DanMan32]

Note that compasses on mobile devices are often out of calibration. Waving the mobile in a figure 8 wrist movement usually will get that sorted out but often impractical when mounted to the remote. However if you know which way is north, the AC's physical heading relative to actual north, you can compare the AC icon on the radar compared to N showing on the radar. If the relationship matches, you're good. If you aren't sure where N really is, then you'll want to calibrate your device.
Of course your device could be biased just as much as the AC.

 

[LivinLarge]

So why does it try to go anywhere unless I hit the RTH button as a Plan B?
I'm perfectly capable of flying with the joysticks. Again there was certainly no wind at the location... I was hovering for only a few seconds among the trees. The drone can certainly hover properly without a gps/compass input. And the first few moments panning northward indicated no issues

The pilot should be in control and the AI features should be assisting, not overriding, so it's very difficult for me to understand that it would just decide to fly away. It seems like as soon as it picked up a GPS signal it just decides that the primary source of control isn't the pilot anymore, fitting the description of "rogue".

Again, I can see how the RTH location might be off, but it updated correctly upon take off right before the flyaway.

Very frustrating that "such smart tech" could be so... Inferior to human control.

You are correct. The drone can certainly hover without GPS or compass. Anyone who has flown earlier drones in ATTI mode would know this. It may drift if there is wind, but will not yaw wildly or suddenly fly full speed in some random direction.
The flight controller in modern drones will switch to ATTI mode if it loses GPS signal. The pilot should still be able to control the drone when this happens. It is a shame that DJI has removed the ability for the pilot to switch to this mode when it is obvious that the drone is not behaving correctly in GPS mode.
Here is an early Phantom being flown without GPS or compass:

 

[sar104]

You are correct. The drone can certainly hover without GPS or compass. Anyone who has flown earlier drones in ATTI mode would know this. It may drift if there is wind, but will not yaw wildly or suddenly fly full speed in some random direction.
The flight controller in modern drones will switch to ATTI mode if it loses GPS signal. The pilot should still be able to control the drone when this happens. It is a shame that DJI has removed the ability for the pilot to switch to this mode when it is obvious that the drone is not behaving correctly in GPS mode.
Here is an early Phantom being flown without GPS or compass:

I didn't interpret the question to be whether or not it would fly off uncontrollably - I took it to mean could the aircraft hover in place without compass data. The answer is no - as the rate gyro and accelerometer drift accumulates it will wander and yaw even without wind.

 

[Meta4]

You are correct. The drone can certainly hover without GPS or compass. Anyone who has flown earlier drones in ATTI mode would know this.
It may drift if there is wind, but will not yaw wildly or suddenly fly full speed in some random direction.

Switching to Atti mode in a Phantom doesn't switch off the compass.
The GPS keeps running and the GPS data is used to log the position of the drone but it doesn't use the GPS data so loses position holding and braking.
But it's still using the compass and knows which way it is facing at all times.

 

[LivinLarge]

Switching to Atti mode in a Phantom doesn't switch off the compass.
The GPS keeps running and the GPS data is used to log the position of the drone but it doesn't use the GPS data so loses position holding and braking.
But it's still using the compass and knows which way it is facing at all times.

As demonstrated in my video the compass is not being used in ATTI mode. It's not even installed. The whole reason to switch to ATTI mode is to ignore bad data from compass or GPS if they are compromised. Data may actually still be recorded but I don't think the compass is being used for control.
I believe the OP could have saved the drone if he could have switched to ATTI mode.

 

[sar104]

As demonstrated in my video the compass is not being used in ATTI mode. It's not even installed. The whole reason to switch to ATTI mode is to ignore bad data from compass or GPS if they are compromised. Data may actually still be recorded but I don't think the compass is being used for control.
I believe the OP could have saved the drone if he could have switched to ATTI mode.

The video, which has been used many times as an example, does show that the aircraft is short-term stable in ATTI mode with no compass input. In other words it is hovering purely using the accelerometers, rate gyros and barometer. The other data are not being ignored, but they are not being used in the sensor fusion process for flight control. Since the most common cause of switching to ATTI mode is yaw errors, it's consistent that it would not use compass data for control in that mode.

 

[LivinLarge]

The video, which has been used many times as an example, does show that the aircraft is short-term stable in ATTI mode with no compass input. In other words it is hovering purely using the accelerometers, rate gyros and barometer. The other data are not being ignored, but they are not being used in the sensor fusion process for flight control. Since the most common cause of switching to ATTI mode is yaw errors, it's consistent that it would not use compass data for control in that mode.

The problem in this case and others I have read about, is when the FC switches back to GPS mode from ATTI mode. It seems the aircraft is trying to maintain its position based on bogus data and starts flying to an incorrect position. Apparently, this function takes precedence over user input as you are not able to override it.

 

[sar104]

The problem in this case and others I have read about, is when the FC switches back to GPS mode from ATTI mode. It seems the aircraft is trying to maintain its position based on bogus data and starts flying to an incorrect position. Apparently, this function takes precedence over user input as you are not able to override it.

I don't recall many (any?) cases of an FC switching back to P-GPS with an unresolved yaw error, followed by uncontrolled flight. The far more common scenario, especially with more recent firmware, is that the FC stays in P-GPS too long after yaw errors occur, and the aircraft goes out of control during that period.

The Phantom range has user-selectable ATTI mode on the mode switch but the Mavics do not, by default. You can change that in the parameter settings though - I have ATTI programmed in place of SPORT mode on my Mavics.

It's certainly true that if the IMU and compass disagree during flight, ATTI mode is your friend since it stops the FC from making a mess of things by trying to hold position and allows you to fly the aircraft to safety. It takes some practice to fly in that mode however - difficult to get on a Mavic without changing the mode switch programming.

 

[Mrmund]

I don't recall many (any?) cases of an FC switching back to P-GPS with an unresolved yaw error, followed by uncontrolled flight. The far more common scenario, especially with more recent firmware, is that the FC stays in P-GPS too long after yaw errors occur, and the aircraft goes out of control during that period.

The Phantom range has user-selectable ATTI mode on the mode switch but the Mavics do not, by default. You can change that in the parameter settings though - I have ATTI programmed in place of SPORT mode on my Mavics.

It's certainly true that if the IMU and compass disagree during flight, ATTI mode is your friend since it stops the FC from making a mess of things by trying to hold position and allows you to fly the aircraft to safety. It takes some practice to fly in that mode however - difficult to get on a Mavic without changing the mode switch programming.

How did you do that?

 

[aokusman]

This is why I have never used quick shots with my mavic air.

 

[sar104]

How did you do that?

You mean the mode switch?

Mavic 2 Atti mode

 

[wreckinball]

Having problems for several flights before the loss should have been a sign to not fly until a thorough check was completed. Some lessons are free, some cost.

 

[Manty]

Thanks for the post. As a newbie it was a lesson in itself.

 

[ac30]

FYI dji is replacing my drone under warranty
Booyah

 

[MavicFlyer]

I learned a lot from reading these messages. Assuming the explanations of how the Mavic works are correct, and I have no reason to think otherwise, DJI was negligent in removing switchable ATTI mode in the Mavics, and continues to be so, especially given the number of drones that have been lost which could have been recovered. This is all $$$$ out of the consumers' pockets!

Checking compass alignment before flying is obviously the easiest way to go, but I don't remember seeing anywhere in the manual how to check alignment - as mentioned in an earlier post in this thread - drone actually pointing North when the display indicates that it is. A picture of what to look for would be worth a thousand words. Essentially, all DJI has to say is move to another location away from metal; this is true, but is not sufficient. Magnetic interference areas are only getting more common as the years go by so DJI needs to make more effort at educating the consumer - something you guys are doing on this forum - CONGRATULATIONS!

A final thought about what to do if this flyaway starts happening to you. If you can't regain control, perhaps you should just force a crash while it is still in view, and over an area where you can recover the pieces to send in for Refresh: Joysticks down and inward, to shut off the motors???

 

[sar104]

I learned a lot from reading these messages. Assuming the explanations of how the Mavic works are correct, and I have no reason to think otherwise, DJI was negligent in removing switchable ATTI mode in the Mavics, and continues to be so, especially given the number of drones that have been lost which could have been recovered. This is all $$$$ out of the consumers' pockets!

Checking compass alignment before flying is obviously the easiest way to go, but I don't remember seeing anywhere in the manual how to check alignment - as mentioned in an earlier post in this thread - drone actually pointing North when the display indicates that it is. A picture of what to look for would be worth a thousand words. Essentially, all DJI has to say is move to another location away from metal; this is true, but is not sufficient. Magnetic interference areas are only getting more common as the years go by so DJI needs to make more effort at educating the consumer - something you guys are doing on this forum - CONGRATULATIONS!

A final thought about what to do if this flyaway starts happening to you. If you can't regain control, perhaps you should just force a crash while it is still in view, and over an area where you can recover the pieces to send in for Refresh: Joysticks down and inward, to shut off the motors???

DJI has never, to my knowledge, advised checking the aircraft orientation arrow to confirm the absence of magnetic interference. I agree that it was unfortunate that they removed user-selectable ATTI.

 

[Mrmund]

Sorry for your loss and many thanks for sharing so we can all learn - this has become a great thread!
I read previously in these forums about checking compass direction in the app is correct and have noticed mine 180° out 2 times in about 50 flights using the previous firmware (4 I think) with no warning popping up in the app. Moving position or calibrating fixed the issue.
I also had magnetic interference once on a big rock in the middle of nowhere, moved it 1m and all ok.

I always wait for good GPS lock before takeoff and move if needs be BUT...
I have been wondering what would happen if you took off in a deep valley for eg, in ATTI and the drone got a GPS lock in flight?
Even if compass and all was OK, would it still drift or toilet bowl a bit before it settled?
There's a few places like this with waterfalls I'd love to fly but without an ATTI mode switch I'm sensibly cautious.
View attachment 53157

If it's "toilet bowling" you should probably redo the IMU.

 

[Mrmund]

I learned a lot from reading these messages. Assuming the explanations of how the Mavic works are correct, and I have no reason to think otherwise, DJI was negligent in removing switchable ATTI mode in the Mavics, and continues to be so, especially given the number of drones that have been lost which could have been recovered. This is all $$$$ out of the consumers' pockets!

Checking compass alignment before flying is obviously the easiest way to go, but I don't remember seeing anywhere in the manual how to check alignment - as mentioned in an earlier post in this thread - drone actually pointing North when the display indicates that it is. A picture of what to look for would be worth a thousand words. Essentially, all DJI has to say is move to another location away from metal; this is true, but is not sufficient. Magnetic interference areas are only getting more common as the years go by so DJI needs to make more effort at educating the consumer - something you guys are doing on this forum - CONGRATULATIONS!

A final thought about what to do if this flyaway starts happening to you. If you can't regain control, perhaps you should just force a crash while it is still in view, and over an area where you can recover the pieces to send in for Refresh: Joysticks down and inward, to shut off the motors???