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Weird Flight & RTH behavior

RokkoRokko

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Location
Palmerston North, New Zealand
Yesterday had weird experience with my Mavic 2 Pro

Launched it by corner to get shots in adjacent Park to get shots of a fair that was on

It WAS windy but not worse than I had flown in b4 with no issue

Noticed my Mav started drifting on its own and seemed to lose control but got it back in control

took my footage

Then the video link vanished and blank phone screen

I then noted RTH activated for low battery

Disconnected my phone & reconnected - got image back

Mav wasn't returning to home point but lowered to point in Park that I had flown over

It had lowered to pre-landing height - about 3 meters

Thanks to screen image return I was able to go to it and found it hovering as amused fair visitors observed

Landed it.

I had wondered if home point had reset while flying over the park.

Checked flight logs and no, it knew where the home point was and the distance from home point was shown as it did the errant RTH

so hoping the experts here will be able to analyse my log and see what happened, coz til I know, I have lost trust in RTH.

Flew today no real issue but did note controller disconnected a couple of times and I pulled out plug to phone then replaced it & that fixed it.

Log files attached
 

Attachments

  • DJIFlightRecord_2020-02-08_[16-45-37].txt
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  • DJIFlightRecord_2020-02-08_[16-33-27].txt
    906.8 KB · Views: 6
Additional - Log from todays flight where the controller connection failed - in case there are clues there

Still a weird issue , at 18 mins 14.9 the drone hovered 34.8 ft away from home point

I manually flew it to where it launched from and forced landing.

Somethings up with the RTH feature - it knows where it is but isn't going to the home point properly

truckload of satellites - 14 odd so, hoping some of yu experienced pilots look at log, go aha.... and tell me of the dumbass mistake I made
 

Attachments

  • DJIFlightRecord_2020-02-09_[16-25-35].txt
    1.7 MB · Views: 7
Last edited:
Checked flight logs and no, it knew where the home point was and the distance from home point was shown as it did the errant RTH
so hoping the experts here will be able to analyse my log and see what happened, coz til I know, I have lost trust in RTH.
At 13:11.4 when autolanding commenced, the following warning message appears in the flight data:
Critically low power. Aircraft is landing.

There's something wrong with the way your battery data is showing.
It's showing that you started with 84% and still had 84% 14 minutes later.
Clearly that can't be correct as the battery has to have run down during the flight.

For the first two seconds of the second flight log, the %indicator shows 16% !!

If you started with 84%, that means the battery was partially discharged.
You need to always launch with a fully charged battery rather than one which has been sitting around and discharging.
Of you launch with a partially discharged battery, your % indicator will not give a correct reading.

RTH was not your problem.
A very low battery was

Here are your flight records in a form you can read:
 
There's no mystery at all about this flight. Combining the logs shows that the aircraft simply autolanded due to low battery when the battery level fell below the computed SMART_BATTERY_landBattery level of 13%.

Battery.png

At 13:11.4 when autolanding commenced, the following warning message appears in the flight data:
Critically low power. Aircraft is landing.

There's something wrong with the way your battery data is showing.
It's showing that you started with 84% and still had 84% 14 minutes later.
Clearly that can't be correct as the battery has to have run down during the flight.

For the first two seconds of the second flight log, the %indicator shows 16% !!

If you started with 84%, that means the battery was partially discharged.
You need to always launch with a fully charged battery rather than one which has been sitting around and discharging.
Of you launch with a partially discharged battery, your % indicator will not give a correct reading.

RTH was not your problem.
A very low battery was

Here are your flight records in a form you can read:

The 84% battery indication on PhantomHelp is an artifact of a log parsing error - it's not real. The flight started at 91% and ended at 3%.
 
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Recommendations:
  1. set your critical low battery warning level to something higher
  2. do not ignore that -- when it goes off, come home. (it could be this was your only problem).
Because auto-landing around people can get you into hot trouble.

It's especially troublesome that you didn't have VLOS of the craft landing (you had to use the controller image to determine where it was).

Chris

Edit: not to mention that if it auto-landed around people, that could mean that you had previously been flying over people. This is one good example is why the rules are (in some to most places) to not fly over people, because this is just one of the things that could happen.
 
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Yesterday had weird experience with my Mavic 2 Pro

Launched it by corner to get shots in adjacent Park to get shots of a fair that was on

It WAS windy but not worse than I had flown in b4 with no issue

Noticed my Mav started drifting on its own and seemed to lose control but got it back in control

took my footage

Then the video link vanished and blank phone screen

I then noted RTH activated for low battery

Disconnected my phone & reconnected - got image back

Mav wasn't returning to home point but lowered to point in Park that I had flown over

It had lowered to pre-landing height - about 3 meters

Thanks to screen image return I was able to go to it and found it hovering as amused fair visitors observed

Landed it.

I had wondered if home point had reset while flying over the park.

Checked flight logs and no, it knew where the home point was and the distance from home point was shown as it did the errant RTH

so hoping the experts here will be able to analyse my log and see what happened, coz til I know, I have lost trust in RTH.

Flew today no real issue but did note controller disconnected a couple of times and I pulled out plug to phone then replaced it & that fixed it.

Log files attached
As noted by @sar104 the M2 auto landed because the SmartBattery sysytem detected that the battery had fallen below the Smart_Battery:landBattery threshold.

But, before that the battery had dropped below the Smart_Battery:goHomeBattery and the M2 was attempting a RTH. Looks to me like it couldn't because of high winds.

At 730 secs the downlink was re-established and the battery was 16% - below the 23% Smart_Battery:goHomeBattery threshold. At this point the flyCState was GoHome. The M2 was tilted ~30° towards the HP for the next 60 secs attempting to RTH. At 760 secs the battery fell below the 13% Smart_Battery:landBattery threshold, but the M2 waited another 30 secs before auto landing.
1581267534023.png
1581268363087.png
1581267514816.png

Also, there were several warnings in the eventLog indicating the M2 was going home and experiencing high winds
737.0,LOW POWER. RETURNING HOME.
738.6,THE REMAINING BATTERY IS ONLY ENOUGH FOR RTH. RETURN HOME NOW.
739.6,HIGH WIND VELOCITY. FLY WITH CAUTION AND LAND IN A SAFE PLACE ASAP.
757.6,THE REMAINING BATTERY IS ONLY ENOUGH FOR RTH. RETURN HOME NOW.
769.6,HIGH WIND VELOCITY. FLY WITH CAUTION AND LAND IN A SAFE PLACE ASAP.
779.6,HIGH WIND VELOCITY. FLY WITH CAUTION AND LAND IN A SAFE PLACE ASAP.
780.6,THE REMAINING BATTERY IS ONLY ENOUGH FOR RTH. RETURN HOME NOW.
791.4,CRITICALLY LOW POWER. AIRCRAFT IS LANDING.
791.4,OBSTACLE AVOIDANCE WILL BE DISABLED IN LANDING.
801.6,HIGH WIND VELOCITY. FLY WITH CAUTION AND LAND IN A SAFE PLACE ASAP.
 
Last edited:
Cheers guys

I appreciate your effort spent on helping me understand this.


I never noticed the 84% continuous battery level when I checked the logs

But the RTH for low battery still kicked in when it should have and it knew where home Point was so my concern is still why it didn't.

I have flown in high winds before strong enough to tilt the aircract [tilted camera image] but the M2 still had no issue flying as I directed.

I knew it was windy, but maybe the wind above me was excessively faster

There were a couple of times during the flight where the M2 drifted and it wouldn't respond to the controller - high winds pushing it?

So you're very confident high wind from the direction of the Home Point stalled its attempts to return there?
 
I knew it was windy, but maybe the wind above me was excessively faster
Up high, where the roughness of the land (trees, houses etc) doesn't slow it, the wind will always be stronger ... sometimes much stronger.

There were a couple of times during the flight where the M2 drifted and it wouldn't respond to the controller - high winds pushing it?
So you're very confident high wind from the direction of the Home Point stalled its attempts to return there?
Look at 12:33.3 - 12:35 and from 12:41.7 - 12:53.6.
The wind gusts were too strong for RTH to make any headway and it was going slowly backwards for those times.
It used up the battery going almost nowhere and autolanded to protect the drone when it reached critical low voltage.
 
Up high, where the roughness of the land (trees, houses etc) doesn't slow it, the wind will always be stronger ... sometimes much stronger.


Look at 12:33.3 - 12:35 and from 12:41.7 - 12:53.6.
The wind gusts were too strong for RTH to make any headway and it was going slowly backwards for those times.
It used up the battery going almost nowhere and autolanded to protect the drone when it reached critical low voltage.


Many thanks bro

I can now trust my Mav again - I was concerned there was a malfunction with RTH

I appreciate and respect you guys willingness to help quickly and effectively

much appreciated.
 
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Another query, based on same flight log
Additional - Log from todays flight where the controller connection failed - in case there are clues there

Still a weird issue , at 18 mins 14.9 the drone hovered 34.8 ft away from home point

I manually flew it to where it launched from and forced landing.

Somethings up with the RTH feature - it knows where it is but isn't going to the home point properly

truckload of satellites - 14 odd so, hoping some of yu experienced pilots look at log, go aha.... and tell me of the dumbass mistake I made

ANOTHER query as I noticed something

at 4 mins 16 in this flight, as "download link restored" occurred, the video jumped out of focus and remained that way regardless of focus button pushes

This has been a recurring issue since I got my M2 in October, however it has always been from the start of the flight and all through it

This time it happened exactly as downlink restored

any ideas?
 
Can’t help you with the focus problem. I would recommend UAV Forecast, a free app, which will amaze you, simply because it will show you wind speeds and gusts at different altitudes. Sometimes the variance between ground level and 250 is startling. It could save your M2.
 
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