Mavic Air started fly away

[Arthur.N]

Hello guys,
after 2 years of flights my Mavic Air attempted to fly away...
Actually the problem started from very begining.
The AC said that it cannot take off. I've checked that I'm not in NFZ.
Switched it off, re-checked battery (pull and put it again), and restarted AC.
After those actions everything went rather smoothly during 8mins 5sec. and when I've started PANO360 shoot I had gotten the message "Aircraft disconnected".
Immediatly after this messgae I've seen that my Mavic start to fly to from point P (see tab Sensors) in parrallel to the shore and slightly toward the sea.
I've not panicked, but I've thought that I may lose my drone. Since I always fly in VLOS, so I've run to the highest point on the hill and turns directly to my AC, and tried to bring it back blindly (the screen was frozen). Few seconds it didn't respond to joysticks input then I've seen it has turned a little. Then I had pressed RTH and it has started to approach to me. I've relaxed, since I've though that everything finished well, but... AC came almost to the home point (few meters from home), but hovered over edge of cost cliff, still do not respond to my input. I've knew that I have not too many time to land it, so I've restarted DJI Go 4 and remote controller. After about a minute the AC started respond and I've succeeded to land it safely. Now, I'd like to understand the reason of such behaviour, since this time I was rather lucky, but next time it may finish with crash.

Here is AirData logs:

Thanks for help.

P.S. I've just realised that AC had flew almost against wind direction (according with Weather tab).
--
AN

 

[Meta4]

Now, I'd like to understand the reason of such behaviour, since this time I was rather lucky, but next time it may finish with crash.

It's difficult to tell what happened because there is no recorded data for the period between 8:16.6 and 12:09.7.
Whatever happened in nearly four minutes is not recorded.
The drone was 14 metres up and 114 metres out and the next record we have shows the drone six metres from home and autolanding.

But your difficulty with control when landing is because you didn't realise the drone was autolanding.
Instead of cancelling the autolanding and resuming control, you fought against the autolanding.

 

[slup]

This was most probably not a mystery & definitely not a fly away ... the MA1 did exactly what it's programmed to do.

1. You lost the AC-RC connection due to some unknown reason at 496,5sec into the flight ... then at 14,3m height relative HP & at a distance of 113,78m from HP, hovering just after a pano shot.

2. The AC most probably then initiated the failsafe action which was "GoHome", ascended up to set RTH height which was 50m & started to fly home.

3. At 729,8sec on 0,3m height & 6m distance from HP you regain the AC-RC connection & the failsafe action was in the landing phase ... in the flight action "GoHomeFinish".

All this shown in the log & depicted in below chart ... have placed the markers just where you have regained the connection, all values from there can be read out from the graph legend below the chart. The large white gap in the chart is the disconnect.

(Click on it to make it larger)


When you regained the connection you was confused & didn't understand what was going on ... you tried to fight the automated RTH function by various manual stick inputs (all shown in below chart) ... the landing was approx 6m off, which can happen. The take away from this is that you should firstly taken off much further away from that cliff edge ... then cancelled the RTH before trying to correct the landing spot.

 

[Arthur.N]

But your difficulty with control when landing is because you didn't realise the drone was autolanding.
Instead of cancelling the autolanding and resuming control, you fought against the autolanding.

I've seen that it did autolanding, but as I had said earlier the screen was frozen with message "Aircraft disconnected" and AC did RTH alone. When it came home (almost) it hovered over edge of cliff (there were no ground under it). So it stopped autolanding alone. I know that I can cancel autolanding at some point or even can move AC horizontally during autolanding, but that was not the case. AC just ignored my joysticks input until I did restart of RC and application. But you know, I didn't see in the log that signal was restored, which is rather strange. Since only after restart of RC I was able to bring AC closer to me and land it manually.

Anyway, thanks for looking at this case.

 

[Arthur.N]

This was most probably not a mystery & definitely not a fly away ... the MA1 did exactly what it's programmed to do.

1. You lost the AC-RC connection due to some unknown reason at 496,5sec into the flight ... then at 14,3m height relative HP & at a distance of 113,78m from HP, hovering just after a pano shot.

It disconnected during PANO shot. By the way it didn't store this shot. I've gotten the message "Aircraft disconnected" and immediatly it started fly away to Southwest. I've tried to move joysticsks without visible result and then hit RTH button (few times with delays between hits) on RC only then I've seen it start RTH procedure. At least I guessed it started fly away, since during RTH procedure AC should fly directly to home if there is no obstacles after it reached specified height (50m in my case). And I've seen it returned to me from South whereas it lost connection a bit North from the home point.

3. At 729,8sec on 0,3m height & 6m distance from HP you regain the AC-RC connection & the failsafe action was in the landing phase ... in the flight action "GoHomeFinish".

When it stopped landing and hovered over edge of cliff I still wasn't able to cancel autolanding or bring AC close to me until I had restarted the RC and the application. I know that during autolanding I can move AC horizontally at least, but not in this case. AC just ignored my inputs. Only after restart of the RC I've succeeded to bring AC close to me and it landed (by itself or with my help, since I've pushed down left stick too). The other stargne thing is that I don't see anything in log that concerns to restart. For example I don't see that radio signal was restored to 100% (it remains 0% at the end).

Is it possible that AC stopped itself autolanding since it didn't see ground under it?

When you regained the connection you was confused & didn't understand what was going on ... you tried to fight the automated RTH function by various manual stick inputs (all shown in below chart) ... the landing was approx 6m off, which can happen. The take away from this is that you should firstly taken off much further away from that cliff edge ... then cancelled the RTH before trying to correct the landing spot.

I've gotten the point about take off further from dangerous things like edges of cliffs and water.

How can I cancel auto landing in case when the application DJI Go 4 is frozen?

Is there a way to analyse logs from AC somethow? I really want to understand why it suddenly lost the connection not so far from me and in VLOS.

Thanks for analysis.

 

[Meta4]

I know that during autolanding I can move AC horizontally at least, but not in this case. AC just ignored my inputs.

You can try, but while RTH autolanding is acting, the drone will keep trying to land where RTH wants to.
You must cancel the RTH autolanding if you want it to go anywhere else.
More than a few crashes have been caused by fighting against RTH autolanding.

Is it possible that AC stopped itself autolanding since it didn't see ground under it?

No .. the drone stayed in Autolanding till the end
And not seeing ground under the drone has no effect.
The drone can land anywhere, higher or lower than the launch point.
It doesn't look for the ground at any particular level.

How can I cancel auto landing in case when the application DJI Go 4 is frozen?

The quickest way is to flick the flight mode switch to Sport mode and back.
That's only going to work if you have signal connection.

 

[slup]

... I've gotten the message "Aircraft disconnected" and immediatly it started fly away to Southwest.

That observation seems to be correct ... from the point where you lost the connection (market with a cross) the direction to the HP is pretty much in a South Westerly direction. The return area would have been approx from the red painted area considering the retracing functionality (see more about that further below...)



What you saw was the automated failsafe functionality in action ... from the manual you can read:

...then hit RTH button (few times with delays between hits) on RC only then I've seen it start RTH procedure

No signs of a RC initiated RTH exists in the flight log, rather natural if your RC wasn't connected to your AC. No RTH command can be relayed if you aren't connected.

You can easily see on your RC if it's disconnected to your AC ... or if it's only the GO4 app that have stopped ... If below LED is green your RC is still connected ... if it's red you're disconnected.

... I don't see anything in log that concerns to restart. For example I don't see that radio signal was restored to 100% (it remains 0% at the end).

How could you? If your RC was disconnected nothing is recorded in the log ... And after the connection is reestablished the log shows full 100% connection ... see the blue graph below. That Airdata says 0% is only their interpretation of the log, you aren't looking at the actual log there.

How can I cancel auto landing in case when the application DJI Go 4 is frozen?

As said ... either you flip it over to Sport or you push the RTH button once ...

Is there a way to analyse logs from AC somethow?

No ... the AC DAT log is encrypted & can only be read by DJI staff.

 

[Arthur.N]

So, I glad that my AC still works properly, according with designed protocols.
The only thing remained not disclosed is why it suddenly lost connection. And as far as I understand w/o AC logs nobody can shed light on this... except may be DJI engineers.

Thank you very much for your explanations.

 

[Van Belle Jean Marc]

This was most probably not a mystery & definitely not a fly away ... the MA1 did exactly what it's programmed to do.

1. You lost the AC-RC connection due to some unknown reason at 496,5sec into the flight ... then at 14,3m height relative HP & at a distance of 113,78m from HP, hovering just after a pano shot.

2. The AC most probably then initiated the failsafe action which was "GoHome", ascended up to set RTH height which was 50m & started to fly home.

3. At 729,8sec on 0,3m height & 6m distance from HP you regain the AC-RC connection & the failsafe action was in the landing phase ... in the flight action "GoHomeFinish".

All this shown in the log & depicted in below chart ... have placed the markers just where you have regained the connection, all values from there can be read out from the graph legend below the chart. The large white gap in the chart is the disconnect.

(Click on it to make it larger)
View attachment 128472

When you regained the connection you was confused & didn't understand what was going on ... you tried to fight the automated RTH function by various manual stick inputs (all shown in below chart) ... the landing was approx 6m off, which can happen. The take away from this is that you should firstly taken off much further away from that cliff edge ... then cancelled the RTH before trying to correct the landing spot.

View attachment 128473

Perfect answer! Due respect. +je

 

[MAvic_South_Oz]

Good the OP got some great feedback on how their drone works.
Goes to show it's worth reading that manual on these important flight functions many time over to help it sink in.

2. The AC most probably then initiated the failsafe action which was "GoHome", ascended up to set RTH height which was 50m & started to fly home.

In hindsight here, considering a very low over ocean flight, no more than approx 46 feet (14 metres) above your take off point, there was absolutely no reason not to set your RTH altitude at say 10m.

Going to 50m RTH on that flight was totally unnecessary, taking you up into perhaps higher winds to fight, and using up valuable battery.
Not sure the drone went to 50m, the data obviously is missing, but assume so, did you notice that on it's flight back ?

I always set mine to a low figure when flying above the ocean, where the ground / sea level is constant and no obstacles exist . . . reset RTH height for every flight to suit surrounding obstacles, and use your battery resources better.