Mavic Air seemingly flew away

[dirkclod]

You guys never cease to amaze me.

Some don’t me ether. Why my gif. I have no clue what I was
looking at but I’m sure it was right. Some very smart members
here as well as our other forums.
Sorry I took it OT but I had one of my moments so let’s get
this back on topic.

 

[ldcam21]

Thanks for the advice. I have insurance but choose to not pay for hull. I'll continue to take my chances based on previous experience but that doesn't mean I will simply flop at the first offer with no pilot error.

Insurance don’t help unless you have the
Copter to give them

 

[BD0G]

Insurance don’t help unless you have the
Copter to give them

Not true in the case of StateFarm insurance and there was one case posted on the forum in which a member was actually able to wrangle a reduced cost of replacement from DJI for a Mavic Pro that he could produce data from (but not the actual drone) that indicated there was a defect that caused loss of the drone which was unrecoverable.

In the large majority of cases you are right that DJI will not honor a refresh claim without the drone being physically available to be returned or presented to them.

 

[JSKCKNIT]

I've been reading just about every fly away posting that's been made. Would hitting the pause flight button work in this type of situation? Asking for personal knowledge, not to criticize or anything like that. Thanks in advance.

 

[VooDooZG]

so why don't we take of sidewalks ?? I don't know, just ask to know in future !?

And another question after another topic like this -- would this happen also to Phantom 4 PRO with 2x compas + IMU ?? also just want to know so I now better what I gonna buy or not in near future ..

thx

 

[sar104]

I've been reading just about every fly away posting that's been made. Would hitting the pause flight button work in this type of situation? Asking for personal knowledge, not to criticize or anything like that. Thanks in advance.

No - that's not going to work because there is no flight action to pause. The FC is simply trying to hold position or respond to stick inputs, but the resulting flight is unstable because the aircraft orientation is not equal to the IMU yaw value.

 

[swooshdave]

so why don't we take of sidewalks ?? I don't know, just ask to know in future !?

And another question after another topic like this -- would this happen also to Phantom 4 PRO with 2x compas + IMU ?? also just want to know so I now better what I gonna buy or not in near future ..

thx

Rebar in the sidewalk's concrete can affect the compass.

 

[JSKCKNIT]

No - that's not going to work because there is no flight action to pause. The FC is simply trying to hold position or respond to stick inputs, but the resulting flight is unstable because the aircraft orientation is not equal to the IMU yaw value.

Thanks

 

[Taylor1430]

No - that's not going to work because there is no flight action to pause. The FC is simply trying to hold position or respond to stick inputs, but the resulting flight is unstable because the aircraft orientation is not equal to the IMU yaw value.

So...if one were in this position, is there a way to stop it from occurring? I know much can be done prior to taking off to prevent this. But, in the instance of some sort of failure in flight, can something be done to prevent the flyoff and have the drone hold it's position or land?

 

[sar104]

So...if one were in this position, is there a way to stop it from occurring? I know much can be done prior to taking off to prevent this. But, in the instance of some sort of failure in flight, can something be done to prevent the flyoff and have the drone hold it's position or land?

Unless you have reprogrammed the mode switch to access ATTI mode manually, there is not much you can do. The entire problem is that the FC cannot hold position, and is in uncontrolled flight. You could simply go to minimum throttle and bring it down, but with no lateral control, or issue a CSC and bring it down really fast with good lateral control. Neither are attractive options.

 

[Taylor1430]

Unless you have reprogrammed the mode switch to access ATTI mode manually, there is not much you can do. The entire problem is that the FC cannot hold position, and is in uncontrolled flight. You could simply go to minimum throttle and bring it down, but with no lateral control, or issue a CSC and bring it down really fast with good lateral control. Neither are attractive options.

Thanks for the prompt reply. Looking for something to have in my bag of tricks if it should hit the fan like this.

 

[sar104]

Thanks for the prompt reply. Looking for something to have in my bag of tricks if it should hit the fan like this.

Good plan. Aside from always checking the aircraft orientation arrow before takeoff, I recommend reprogramming the mode switch.

 

[ddublu]

Good plan. Aside from always checking the aircraft orientation arrow before takeoff, I recommend reprogramming the mode switch.

Very helpful. Thanks again for the assistance.

 

[ddublu]

Good plan. Aside from always checking the aircraft orientation arrow before takeoff, I recommend reprogramming the mode switch.

How do you do that?

 

[sar104]

How do you do that?

DJI Assistant 2 v 1.1.2 (not the current version) with developer tools and debug mode enabled - a quick search will reveal how to do that. Then change "g_config_control_control_mode[1]" from 8 (Sport mode) to 3 (ATTI).

 

[jimprayn]

The comparison of location computed from IMU x and y velocities with the fusion location using GPS is fascinating and alarming. The markers are at one second intervals, with the 15 s locations indicated.

View attachment 38686

If you look at the pitch, roll and yaw data the issue becomes clearer:

View attachment 38687

Note that after the start of significant motion around 8 seconds, and especially after 15 seconds, the pitch is negative and the roll is small. The indicated yaw is approximately north before turning CCW towards NW. That combination should cause the aircraft to move forwards, towards the north, but it is actually moving south. That means that the yaw is almost 180° off. A 180° yaw error will cause exactly this kind of uncontrolled flight in P-GPS as the FC attempts to correct the motion but with exactly the opposite pitch and roll than is actually needed.

The next question is how can the yaw be 180° off if it was initialized correctly, as "appeared" to be the case. The only suggestion I can offer there is that the OP actually placed the aircraft facing the NE and incorrectly thought that it was facing SW. That's only a hypothesis, however.

If that were correct, however, then the explanation is magnetic distortion at the takeoff location, causing the yaw to initialize 180° off the correct value.

The comparison of location computed from IMU x and y velocities with the fusion location using GPS is fascinating and alarming. The markers are at one second intervals, with the 15 s locations indicated.

View attachment 38686

If you look at the pitch, roll and yaw data the issue becomes clearer:

View attachment 38687

Note that after the start of significant motion around 8 seconds, and especially after 15 seconds, the pitch is negative and the roll is small. The indicated yaw is approximately north before turning CCW towards NW. That combination should cause the aircraft to move forwards, towards the north, but it is actually moving south. That means that the yaw is almost 180° off. A 180° yaw error will cause exactly this kind of uncontrolled flight in P-GPS as the FC attempts to correct the motion but with exactly the opposite pitch and roll than is actually needed.

The next question is how can the yaw be 180° off if it was initialized correctly, as "appeared" to be the case. The only suggestion I can offer there is that the OP actually placed the aircraft facing the NE and incorrectly thought that it was facing SW. That's only a hypothesis, however.

If that were correct, however, then the explanation is magnetic distortion at the takeoff location, causing the yaw to initialize 180° off the correct value.[/QUOTE

 

[jimprayn]

I’m a new pilot, so this may be a dumb question, but how do you pull up all the flight data?

Just reading these posts blows me away!

 

[sar104]

I’m a new pilot, so this may be a dumb question, but how do you pull up all the flight data?

Just reading these posts blows me away!

There are two kinds of log files on the mobile device - the txt log and the DAT file. The DAT file is more comprehensive:

DJI Flight Log Viewer

How to retrieve a V3.DAT from the tablet

The aircraft itself has a much more detailed and faster data rate DAT file, but it can be difficult to retrieve from later Mavics:

How to retrieve a V3 .DAT File from the AC

 

[msinger]

A few other log viewing tools can be found here.

 

[ddublu]

DJI ended up changing their offer from 30% off to 50% off for the Mavic Air replacement (aircraft and battery only). I found that to be interesting.