Connection issues and RTH not responding

[CuriousGeorge]

During flight the DJI app / controller disconnected from Mavic Pro. I have it set to RTH if there is a disconnection, the app also prompted me to RTH which I selected. It sat and hovered for two minutes, reconnected I was able to fly it about 50m closer, then it disconnected again for another two minutes. It simply sat and hovered. It eventually reconnected and I was able to fly it back so I guess it's a happy ending.

Two questions - any thoughts on why would it disconnect (twice) and why did it not RTH? I'm nervous to fly it very far, my fear is that it stops responding, auto lands where it shouldn't if RTH isn't working, causes damage or it's not able to be retrieved due to bad terrain.

Details:

1. It was approximately 650-700 meters away when it disconnected
2. It was approximately 80-90 meters altitude
2. 15 satellites
3. Full line of sight
4. No obstructions (flying well above the trees)
5. In the middle of the country, can't imagine there would be any inteference
6. Was not flying into the sun or anything that would have intefferred with RTH obstacle detection

 

[ac0j]

Do you have it set to hover at loss of connection?

 

[CuriousGeorge]

No - I had it set to RTH if there is a disconnection.

 

[ac0j]

We may need to have @msinger or someone take a look at the flight logs. They will be along shortly to help you out!

 

[CuriousGeorge]

Thanks guys, I've had a number of issues since I purchased the Mavic, both hardware and flight related. It's been over a week and DJI has not called after multiple requests where they confirmed they would call back within 1-2 hours (there is no toll free number for Canada). I'll hang tight!

 

[CuriousGeorge]

Anyone that can have a look? Best practices for getting the flight log onto a Mac? I've been through a few threads that are older and seem antiquated

 

[ac0j]

Maybe @sar104 can coach you on getting the log info needed to see whats going on?

 

[sar104]

Maybe @sar104 can coach you on getting the log info needed to see whats going on?

The aircraft DAT file would be the most useful - if it is accessible, which they are sometimes not on later Mavics:

How to retrieve a V3 .DAT File from the AC

If not, then the DAT and txt files from the mobile device:

How to retrieve a V3.DAT from the tablet

DJI Flight Log Viewer - Phantom Help

 

[CuriousGeorge]

There were two disconnections noted (I can provide the entire log if you would like to have a look but thought this may be a good start without having to spend time combing through to find it during a 20 min flight, although I'm not an expert there was nothing notable in the messages beyond the downlink, RTH home point was set 50m, was briefly in a few other modes; sport, POI, active track, but nothing at the time of disconnections):

1. It was for sure down longer than stated, it seemed the first was at least a minute then was unresponsive and disconnected again

7m 36.2s P-GPS 15satellites 308.1ft N/A 0mph 2,574.1ft 67% 11.642V 3.884V 3.882V 3.876V 0.008V
7m 36.4s P-GPS 14satellites 308.1ft N/A 0mph 2,574.1ft 67% 11.642V 3.884V 3.882V 3.876V 0.008V
7m 36.6s P-GPS 15satellites 308.1ft N/A 0mph 2,574.1ft 67% 11.642V 3.884V 3.882V 3.876V 0.008V
7m 37.2s P-GPS 14satellites 308.1ft N/A 0mph 2,574.1ft 67% 11.634V 3.882V 3.879V 3.873V 0.009V
7m 38.8s P-GPS 15satellites 308.1ft N/A 0mph 2,574.3ft 66% 11.633V 3.881V 3.879V 3.873V 0.008V
7m 44.1s P-GPS 15satellites 308.4ft N/A 0mph 2,574.1ft 66% 11.633V 3.881V 3.879V 3.873V 0.008V Downlink Restored (after 0m 4.7s)
7m 45s P-GPS 15satellites 308.4ft N/A 0mph 2,574.0ft 66% 11.62V 3.877V 3.874V 3.869V 0.008V
7m 47.1s P-GPS 15satellites 308.4ft N/A 0mph 2,573.9ft 66% 11.618V 3.876V 3.874V 3.868V 0.008V
7m 48.8s P-GPS 15satellites 308.1ft N/A 2.4mph 2,573.3ft 66% 11.618V 3.876V 3.874V 3.868V 0.008V
7m 48.9s P-GPS 15satellites 308.1ft N/A 3.3mph 2,572.8ft 66% 11.618V 3.876V 3.874V 3.868V 0.008V
7m 49s P-GPS 15satellites 308.4ft N/A 3.3mph 2,572.2ft 66% 11.618V 3.876V 3.874V 3.868V 0.008V

2.

7m 58.8s P-GPS 15satellites 308.1ft N/A 20.2mph 2,353.1ft 65% 11.602V 3.871V 3.868V 3.863V 0.008V
7m 58.9s P-GPS 15satellites 308.1ft N/A 20.2mph 2,350.3ft 65% 11.602V 3.871V 3.868V 3.863V 0.008V
7m 59s P-GPS 15satellites 308.1ft N/A 20.2mph 2,347.5ft 65% 11.602V 3.871V 3.868V 3.863V 0.008V
7m 59.1s P-GPS 15satellites 308.1ft N/A 20.2mph 2,344.8ft 65% 11.602V 3.871V 3.868V 3.863V 0.008V
7m 59.2s P-GPS 15satellites 308.1ft N/A 20.2mph 2,342.0ft 65% 11.602V 3.871V 3.868V 3.863V 0.008V
7m 59.3s P-GPS 15satellites 308.1ft N/A 20.2mph 2,339.2ft 65% 11.607V 3.872V 3.87V 3.865V 0.007V
7m 59.4s P-GPS 15satellites 308.1ft N/A 20.2mph 2,336.4ft 65% 11.607V 3.872V 3.87V 3.865V 0.007V
9m 48.4s P-GPS 15satellites 308.1ft N/A 20.2mph 2,145.3ft 65% 11.607V 3.872V 3.87V 3.865V 0.007V Downlink Restored (after 1m 49s)
9m 49s P-GPS 15satellites 308.1ft N/A 0mph 2,145.4ft 58% 11.448V 3.82V 3.817V 3.811V 0.009V Your aircraft has entered a Warning Zone (Unpaved Airports). Please fly with caution.
9m 50s P-GPS 15satellites 308.1ft N/A 0mph 2,145.4ft 58% 11.448V 3.82V 3.817V 3.811V 0.009V
9m 51.4s P-GPS 15satellites 308.1ft N/A 0mph 2,145.4ft 58% 11.448V 3.82V 3.817V 3.811V 0.009V
9m 52.4s P-GPS 15satellites 308.1ft N/A 0mph 2,145.4ft 58% 11.445V 3.819V 3.816V 3.81V 0.009V
9m 52.6s P-GPS 15satellites 308.1ft N/A 0mph 2,145.4ft 58% 11.445V 3.819V 3.816V 3.81V 0.009V
9m 54.6s P-GPS 15satellites 308.1ft N/A 0mph 2,145.4ft 58% 11.444V 3.818V 3.816V 3.81V 0.008V
9m 55s P-GPS 15satellites 307.7ft N/A 0mph 2,145.4ft 58% 11.441V 3.817V 3.815V 3.809V 0.008V
10m 0s P-GPS 15satellites 308.1ft N/A 0mph 2,145.5ft 57% 11.435V 3.815V 3.813V 3.807V 0.008V
10m 3.2s P-GPS 15satellites 307.7ft N/A 0mph 2,145.7ft 57% 11.429V 3.813V 3.811V 3.805V 0.008V
10m 3.3s P-GPS 15satellites 307.7ft N/A 0mph 2,145.7ft 57% 11.429V 3.813V 3.811V 3.805V 0.008V
10m 3.9s P-GPS 15satellites 307.7ft N/A 0mph 2,145.7ft 57% 11.424V 3.812V 3.809V 3.803V 0.009V
10m 5s P-GPS 15satellites 308.1ft N/A 0mph 2,145.9ft 57% 11.424V 3.812V 3.809V 3.803V 0.009V
10m 6.5s P-GPS 15satellites 307.7ft N/A 2.3mph 2,144.9ft 57% 11.425V 3.812V 3.809V 3.804V 0.008V
10m 6.6s P-GPS 15satellites 307.7ft N/A 4.0mph 2,144.3ft 57% 11.425V 3.812V 3.809V 3.804V 0.008V

 

[sar104]

That's not nearly enough information to figure out what is happening. See post #8.

 

[CuriousGeorge]

My apologies I only pulled the .txt file out when reading the second part of your post. I will get the .DAT file and full flight log posted (hopefully this evening)

 

[sar104]

My apologies I only pulled the .txt file out when reading the second part of your post. I will get the .DAT file and full flight log posted (hopefully this evening)

If you can post the txt and DAT files that would be best.

 

[HWCM]

No - I had it set to RTH if there is a disconnection.

Double check that. Make sure both the Mavic and controller are on and connected when making settings changes, as the settings are stored on the Mavic.

 

[CuriousGeorge]

Attached the dat and txt. Thanks in advance for taking a look.

@HWCM The settings had been updated during a previous flight (updated RTH height to 50m) and were verified prior to take off.

 

[CuriousGeorge]

Any insights? I FINALLY spoke with DJI support - they wanted nothing to do with the logs and their sole suggestion was to:

1. Reinstall firmware
2. Calibrate IMU (Before EVERY flight)
3. Calibrate Compass (Before EVERY flight)
4. Do a max distance test

I'm still nervous flying, especially given the yellow light flashing I've been having lately, but will be doing a distance test this week with a friend at the other end. Everything I've seen seems to say the IMU should only be calibrated when prompted (even from DJI themselves), and the compass when travelling a greater distance. Calibrating both before every flight ¯\_(ツ)_/¯

 

[sar104]

Any insights? I FINALLY spoke with DJI support - they wanted nothing to do with the logs and their sole suggestion was to:

1. Reinstall firmware
2. Calibrate IMU (Before EVERY flight)
3. Calibrate Compass (Before EVERY flight)
4. Do a max distance test

I'm still nervous flying, especially given the yellow light flashing I've been having lately, but will be doing a distance test this week with a friend at the other end. Everything I've seen seems to say the IMU should only be calibrated when prompted (even from DJI themselves), and the compass when travelling a greater distance. Calibrating both before every flight ¯\_(ツ)_/¯

I apologize – I didn't get around to looking at the files you posted. I'll do that and get back to you.

 

[SYC12]

To OP,

1. You said that both DJI GO4 & controller disconnected from MP, then how you got a RTH request from GO4?

2. What’s message you got from GO4 when you believed GO4 disconnects from MP? Was it “aircraft disconnected “?

 

[CuriousGeorge]

This was several days ago now, a little foggy on some of the details, that being said here's what I remember:

1. It said disconnected - a few seconds at most after a message appeared with a 'swipe' to return home. It didn't make sense to me because if it's disconnected it should have no way to communicate, why even prompt a command that cannot be issued? The behaviour I expected based on my settings, the manual etc was that it would ascend if needed and return home after a very brief disconnection. It did not.

2. I can't recall the exact message if any. The video feed went down and it said 'disconnected' in the top left corner. I don't recall the exact message on the remote

 

[SYC12]

If you search “aircraft disconnected” you will find a lot MP pilots have this BIG issue and have no idea what is the reason causing it.
It happened to me twice but both time my connector was still working.

As why we got “aircraft disconnected “, the followings are my thoughts:

1. I believe that we are getting this issue because we have updated to the latest GO4/FW. All the pilots will tell you the first year after the introduction of MP, nobody has this issue.

2. In order to resolve the flyaway issue in the earlier Phantom drone, DJI started to use dual compass in MP. GO4 will pick the campass with smaller value (less interference) for navigational purposes. Calibrate compass (or IMU) will make both campass (or IMU) values more accurate thus less likely to trigger an unforeseen program coding error.

3. I have to say this is my unproven theory and I am still in the process of testing

 

[sar104]

The log shows the two periods of downlink interruption, but it does not appear that the aircraft ever switched to RTH - it hovered simply because it was not receiving any stick inputs. Just a guess, but that suggests to me that perhaps the downlink was not lost but that the app lost connection with the RC. Do you recall if the RC itself indicated a loss of connection?

It may also be possible that the downlink was lost but the uplink was still intact, so that the aircraft did not know that it had lost connection. I've always been a bit hazy on exactly what happens if the link goes down asymmetrically, because it seems to be rare in posted logs and I've never seen both aircraft and app logs for such an event.

The app txt and DAT files are obviously missing the aircraft data when not connected to the aircraft. If you are able to access the aircraft DAT file that will tell us the aircraft state during those two periods of downlink (or app connection) loss.