Slightly erratic behaviour

[bewa]

I've had a handful of flights with out any issues with my MA and i'm currently on the latest firmware version (aircraft/controller) and DJI go app on Android (OnePlus 6 (9.0.2)). Weather about 3/4 degrees C but dry calm with little to no wind and no fog/mist.

Today however was the first flight on 2.4ghz (and this could have been the issue) and a PolarPro ND4 filter. The flight process started off with calibrating the compass 3 times (first two it complained ).

The flight started off ok doing my usual get it up in the air with auto-take off and a precision RTH selected. However as the flight progressed the MA would just suddenly stop and not respond to controls then it the control would return however would go slightly weird again and stop and i found the video feed quite glitchy.

Here's the uploaded flight log: DJI Flight Log Viewer - PhantomHelp.com

I see there's a couple of entries regarding downlink restored and I remember at the time it said signal was lost. I also noticed at 3m 5.3s there is a battery cell deviation marked as red.

On checking another log file i found in the dji go app directory there are these entries

## 07:30:38
GEO: You are in a Warning Zone (Unpaved Airports). Fly with caution.
## 07:30:41
Home Point recorded. Return-to-Home Altitude:98FT
## 07:33:19
Attitude is too large. Forward Obstacle Sensing is not functioning.
## 07:33:19
Attitude is too large. Backward Obstacle Sensing is not functioning.
## 07:33:39
Strong Aircraft Interference

The flight ended not with landing (or crashing) but it was hovering at about 6ft, refused to land so i managed to grab it from the front and flip it over to stop the engines (the not recommended way obviously). I've flown in this location before without any issues which is weird.

I'd appreciate some thoughts or perhaps if you think i should contact DJI support i will?

 

[Kilrah]

Just suggests high interference on the 2.4GHz band at that location.

 

[bewa]

Just suggests high interference on the 2.4GHz band at that location.

And do you think that's the most likely reason for that behaviour?
I only selected 2.4ghz (custom) because i wanted better range at that location but perhaps i should know better than to override what DJI pre-selected for that location!

 

[大疆御Air]

2.4 not necessarily gives good range unless you are on open areas. 5.8 still the best for most area especially Urban

 

[Meta4]

The flight process started off with calibrating the compass 3 times (first two it complained ).

Was there a particular reason you were calibrating the compass?
It should not be necessary at all.
That multiple attempts failed is a bit of a red flag but it would be unrelated to the issues you saw.

I see there's a couple of entries regarding downlink restored and I remember at the time it said signal was lost. I also noticed at 3m 5.3s there is a battery cell deviation marked as red.

You lost downlink a couple of times. This is not a big deal.
A 0.1 volt deviation is no problem and couldn't affect control of the drone.

The flight ended not with landing (or crashing) but it was hovering at about 6ft, refused to land so i managed to grab it from the front and flip it over to stop the engines (the not recommended way obviously). I've flown in this location before without any issues which is weird.

The flight data looks normal for much of the flight but there's something odd in your flight data toward the end of the flight.

You lose downlink at 5:45.3 and it comes back 17.8 seconds later.
When it comes back, the throttle is registering 1185 (centred =1024) and it stays at 1185 until the end of the flight record at 6:12.8 - that's about 9 seconds later.

This is suspicious because:
If you were trying to land, I would expect the throttle to be in the down position (<1024) .. and
I wouldn't expect you could hold the left joystick perfectly still for 9 seconds.

I'm not sure what's going on there but would first check your joystick calibration to confirm that isn't the problem.

 

[bewa]

Was there a particular reason you were calibrating the compass?
It should not be necessary at all.
That multiple attempts failed is a bit of a red flag but it would be unrelated to the issues you saw.

It said before taking off that the compass needed calibrating.

The flight data looks normal for much of the flight but there's something odd in your flight data toward the end of the flight.

You lose downlink at 5:45.3 and it comes back 17.8 seconds later.
When it comes back, the throttle is registering 1185 (centred =1024) and it stays at 1185 until the end of the flight record at 6:12.8 - that's about 9 seconds later.

This is suspicious because:
If you were trying to land, I would expect the throttle to be in the down position (<1024) .. and
I wouldn't expect you could hold the left joystick perfectly still for 9 seconds.

I'm not sure what's going on there but would first check your joystick calibration to confirm that isn't the problem.

Yes this is when things got really weird as it tried ascending and it was like i was fighting to descend and then eventually. unless i just started doing weird stuff in the heat of the moment, which could be possible for an amateur/novice like my self.
and at the end of the flight before i grabbed it, there was no response at all, apart from when i tried grabbing from the back that upset the avoidance sensors so it slight ascended by an inch or two.

 

[Meta4]

It said before taking off that the compass needed calibrating.

If you think it's telling you that you need to recalibrate, check again.
Because it's probably saying Move Aircraft or Calibrate Compass.
And due to DJI's very bad wording, it really means Move the Aircraft away from the magnetic influence that is upsetting the compass.
Calibrating the compass won't do anything to fix that problem which was probably why your attempts to recalibrate didn't work.

Something was telling the Mavic that you had the left stick pushed a little forward for the last 9 seconds.
If you were trying to land, you were probably pulling the left stick downwards.
You need to check the joystick calibration to see if the joysticks are working properly or not, to at least eliminate that.

 

[bewa]

If you think it's telling you that you need to recalibrate, check again.
Because it's probably saying Move Aircraft or Calibrate Compass.
And due to DJI's very bad wording, it really means Move the Aircraft away from the magnetic influence that is upsetting the compass.
Calibrating the compass won't do anything to fix that problem which was probably why your attempts to recalibrate didn't work.

I'll pay more attention to the wording, it does show up every other flight from memory, could be wrong though. I don't tend to fly in urban areas though.

Something was telling the Mavic that you had the left stick pushed a little forward for the last 9 seconds.
If you were trying to land, you were probably pulling the left stick downwards.
You need to check the joystick calibration to see if the joysticks are working properly or not, to at least eliminate that.

I've now done the joystick calibration so we'll see if that helps.

As i mentioned i've reverted the wifi signal from custom (2.4ghz) back to Auto which has gone back to 5.8ghz.