RTH failure - need help locating my drone

[zorrex]

Hello,

first, I never had issues with my Mavic Pro. I owned the drone for 2 years and been in the air literally hundreds of times. Never had any accident.

BUT
Yesterday, when the drone was in the air for like 5 minutes (about 1500 ft away), suddenly the phone disconnected. OK, not a big deal. I unplugged the cable, plugged it in again, restarted the app. Nothing. OK, not a problem. I hit the RTH and the drone was approaching home. I was able to see that the distance on the RC is going down, so I was like - OK, it's coming home. Suddenly the RC disconnected from the drone and it wasn't able to get it reconnected again. I restarted it and nothing. I was trying to see the drone, but I didn't see it anywhere. So I waited for it to land. Nothing. I waited for like 30 minutes, restarted the RC couple more times and still nothing. I searched the whole area close to home point and nothing.

So I went home, analysed the phone log file and last know location of the drone was above river when the phone disconnected. I was thinking, there should be some log in the RC too, since it was connected to the drone longer. So I did some research and yes - there is what is called Black Box in the RC too. I downloaded it. Found a way to decrypt it and was able to see what was happening with the drone.

Based on the log from the RC the drone was approaching the home point when at a distance of 27ft from the home point the distance suddenly changed to 999999ft !!! and the drone kept on flying. The remote control was connected for another 3 minutes to the drone - the distance was still 999999ft. And after those 3 minutes the RC disconnected and wasn't able to connect any more.

So here's my question. What do you think happened? Did the drone had some type of glitch, when it suddenly started to think it is 999999ft away from the home point and it kept on trying to approach to the home point? If yes - would you assume it kept on flying the same direction? Or?

I would like to locate the drone - there is high chance it didn't hit anything, so it was able to land somewhere - it still had 52% battery when it lost the connection with RC.

Thank you.

 

[Meta4]

So here's my question. What do you think happened? Did the drone had some type of glitch, when it suddenly started to think it is 999999ft away from the home point and it kept on trying to approach to the home point? If yes - would you assume it kept on flying the same direction? Or?

It doesn't matter what some people might guess as to what happened.
What's important is to look at the recorded flight data to find out what really happened.
Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report of the flight.
Come back and post a link to the report it gives you.
The data should help solve the mystery and with a little luck, might point to a likely search area.

 

[zorrex]

It doesn't matter what some people might guess as to what happened.
What's important is to look at the recorded flight data to find out what really happened.
Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report of the flight.
Come back and post a link to the report it gives you.
The data should help solve the mystery and with a little luck, might point to a likely search area.

Please read my entire post. I already did that - the log shows last known location when the phone disconnected (about 1500ft away from home point). Which is totally useless since I know the drone was able to approach the home point to the distance of 27ft.

 

[Meta4]

Please read my entire post. I already did that - the log shows last known location when the phone disconnected (about 1500ft away from home point). Which is totally useless since I know the drone was able to approach the home point to the distance of 27ft.

I did.
If you want help, I've told you want you need to do.
There are people here that can analyse recorded flight data and see a lot you might not have.

 

[zorrex]

Here is the log - DJI Flight Log Viewer - PhantomHelp.com

 

[Meta4]

Here is the log - DJI Flight Log Viewer - PhantomHelp.com

That's the data for the first 7:21 and leave the drone hovering above the bridge where the phone disconnected.
It's what happened after that that's important.

Based on the log from the RC the drone was approaching the home point when at a distance of 27ft from the home point the distance suddenly changed to 999999ft !!! and the drone kept on flying. The remote control was connected for another 3 minutes to the drone - the distance was still 999999ft. And after those 3 minutes the RC disconnected and wasn't able to connect any more.

Can you post data from this part of the flight?

 

[zorrex]

That's the data for the first 7:21 and leave the drone hovering above the bridge where the phone disconnected.
It's what happened after that that's important.

I know.

Can you post data from this part of the flight?

I have only data from the remote controller black box - not the phone log, because the phone never connected to the remote controller again. And the log from the RC black box isn't in the same format as the standard phone log, so I can't upload it to the website you posted earlier.

 

[Meta4]

I have only data from the remote controller black box - not the phone log, because the phone never connected to the remote controller again. And the log from the RC black box isn't in the same format as the standard phone log, so I can't upload it to the website you posted earlier.

That's the data that matters.
Are you able to post the raw data somehow, either direct here or upload to dropbox (or similar) and post a link.

 

[zorrex]

That's the data that matters.
Are you able to post the raw data somehow, either direct here or upload to dropbox (or similar) and post a link.

Here it is - https://we.tl/t-nXovF1MvJB

 

[Meta4]

Here it is - fatal.log

Looks like a case for @sar104

 

[zorrex]

Looks like a case for @sar104

Thank you!

 

[sar104]

Thank you!

Fatal.log is encrypted, so not much use. The txt log doesn't give many clues either. Can you get the mobile device DAT file FLY133.DAT?

How to retrieve a mobile device DAT file: How to retrieve a V3.DAT from the tablet

 

[zorrex]

Fatal.log is encrypted, so not much use. The txt log doesn't give many clues either. Can you get the mobile device DAT file FLY133.DAT?

How to retrieve a mobile device DAT file: How to retrieve a V3.DAT from the tablet

I know, it's actually pretty easy to decrypt fatal.log ... See MAVProxyUser/DJI_ftpd_aes_unscramble

Here is the FLY133.DAT - 19-11-28-02-29-37_FLY133.DAT

Thank you

 

[sar104]

I know, it's actually pretty easy to decrypt fatal.log ... See MAVProxyUser/DJI_ftpd_aes_unscramble

Here is the FLY133.DAT - 19-11-28-02-29-37_FLY133.DAT

Thank you

Okay - I don't see anything useful in the DAT file either.

 

[zorrex]

Okay - I don't see anything useful in the DAT file either.

Thank you, what do you use to open the DAT file?

 

[sar104]

Thank you, what do you use to open the DAT file?

DatCon

 

[Dave Maine]

When you describe the phone disconnecting, what do you mean? Did you just loose picture? Normally the display app is always connected to the rc via cable and never gets disconnected unless you have a bad cable or pull it out of the socket. Most video failures come when the downlink from the ac to the controller fails. This is caused by the downlink being blocked by something, or strong interference. Restarting the app, or unplugging and replugging the cable won’t change the cause of the problem which is the downlink speed.

you will often have an intact uplink which will allow the controller to send flight commands still. If true climb and hope that height will clear the signal path. It may also accept a clean RTH signal to get trrough to the drone. This entire problem situation is confusing and scary when it happens so thinking it through beforehand and planning your response ahead of time will help.

 

[sar104]

When you describe the phone disconnecting, what do you mean? Did you just loose picture? Normally the display app is always connected to the rc via cable and never gets disconnected unless you have a bad cable or pull it out of the socket. Most video failures come when the downlink from the ac to the controller fails. This is caused by the downlink being blocked by something, or strong interference. Restarting the app, or unplugging and replugging the cable won’t change the cause of the problem which is the downlink speed.

you will often have an intact uplink which will allow the controller to send flight commands still. If true climb and hope that height will clear the signal path. It may also accept a clean RTH signal to get trrough to the drone. This entire problem situation is confusing and scary when it happens so thinking it through beforehand and planning your response ahead of time will help.

DJI GO 4 app disconnects from the RC are relatively common, especially with certain Android devices/flavors, as well as due to bad cables.

 

[sar104]

Thank you, what do you use to open the DAT file?

I've never examined a decrypted fatal.log, but if you want to share it and/or elaborate on the contents that you are seeing then I'd be happy to take a look.

 

[Dave Maine]

I guess I am spoiled by the iPd iPhone experience. Never had one, nor talked with any iPad user that did.