We have all seen the dramatic  claims of drone equipment failure, including "Aircraft Disconnected" and wondered why?
We have probably wondered what to do if this unsimulatable crisis should happen to us. Well, I have, and I am glad I did.
What actually happened? I had lined up to take a photo of a lighthouse. I took the pic and seconds later I lost all connection with the aircraft The screen also told me so and the picture froze.
I had two serious concerns.
1/ The battery was low at 17.50 mins into the flight and it would not give me much time to drive to the location and pray, catch it, phone a friend…
2/ If the craft drifted for any reason, it could fly into the lighthouse. After all, it was on its own. Eventually, perhaps if the drone was still responding to its own programming, it would return to home and still collide with the lighthouse.
I had prepared some sort of contingency plan after reading other peoples reports.
Frantically, I shut down the controller. The press and re-press procedure to switch off was not working because in my panic, my timings were all over the place. OK, it shut down and now I was truly out of contact.
Next, I killed off all running applications on my phone. Hell, simple things take an eternity. OK, light up Go4.
Restart the controller.
Craft reconnected and picture restored. BUT where the heck was the drone now? Nothing on the screen looked remotely like a lighthouse, just open scrubland devoid of all familiar land marks.
Seconds after scrutinising the readouts on the screen, I noticed the BIG red cross. Joy of joys it was returning home. Hopefully the same ‘Home point’ it started from.
I stopped the return home, because I needed to know where the craft actually was.
WARNING Battery DANGEROUSLY LOW
Holy c**p even if it was still near the lighthouse, I would be hard pushed to get home.
Think, think! Where is the drone?
I tapped the mini-map and went large. Relief, it was heading to the take off home point.
More warnings from the bitch in the controller.
I had taken back control.
Mr Mavic was coming home! Yea!
The battery was actually at 12% when it landed, so dropping from the sky was not actually imminent.

For those who are interested, here are some facts so possible reasons can be put forward.

Phone, Samsung J7 with Nougat firmware update the day before the flight.  NB the previous test flight went well and had no issues. However, the next consecutive flight, after battery change, threw up a constant stream of warning messages about entering airspace, tick to confirm… As a result, I landed, switched everything off and restarted with 3 minutes of the battery used.
The flight went well and no repeat of the air space warning.
I had killed off all running apps, but one might have come back and caused the disconnect. It is Opera Max, which is supposed to reduce data consumption and limit some running apps. I have never used this app before and will prevent it working. It may not have had any part in the problem, but why take the risk.
Weather fine, sunny and wind about 9 miles per hour.
Only one known source of radio interference in the area and Mr Mavic was well away from it.
It is unlikely there is a radio source on this lighthouse. I have been in it and it is light only. However, I will make enquiries.
After looking at the flight map and data, all data stopped being recorded immediately after the photo was taken.
The map and data after restart of the controller showed the flight on its way home, in a direct line from the lighthouse. I can only surmise that it went into return to home, went straight up and pointed towards home.

Assuming no drift, had the drone dropped from the sky at the lighthouse, it would have fallen on waste land. OK, I know that now, but in my panic, I feared the worst.

  Any thoughts that would help someone else?

Thank you for your detailed report! It confirms that there are options for action if the pilot is not completely paralysed by panic. I am happy that it all ended well for you, good job!

Glad you got your bird back in one piece

Wachtberger Posted at 2018-3-21 04:15
Thank you for your detailed report! It confirms that there are options for action if the pilot is not completely paralysed by panic. I am happy that it all ended well for you, good job!

Thank you. Great relief, I can tell you.

Woe Posted at 2018-3-21 04:22
Glad you got your bird back in one piece

Yup, Mr Mavic will spend a few batteries-full being tested, before I regain my confidence.

Are you sure the actual controller disconnected as well?  Something similar happened to me on my second flight with the mavic pro.  The DJI go app said disconnected, screen went black and white I think, and the controller beeped.  I wasn't too far away, maybe 400 feet?  The MP just stayed there in a hover.  The app was dead, but the sticks and buttons on the remote still worked.  Hit the RTH button, and it started climbing and coming back to me.  While on the way back, I killed the app and restarted it, and the DJI go app reconnected.  I ended up aborting the RTH before it landed, I think.

If it happens again, see if you still have control via the sticks, and can initiate at RTH...

Great narrative - palpitations just reading it! These 'disconnects' though are really an issue, as even the flight record gets cropped off and slightly corrupted. I had 2 flight records show for the same flight as the re-connect registered as a new flight!  So with these it is very hard to nail done the actual cause - if it is from and external source or if it is a bug in the firmware/software and on which device - drone, RC or Go4.

Great save. I can relate to that dreadful feeling..

AlansDronePics Posted at 2018-3-21 04:26
Yup, Mr Mavic will spend a few batteries-full being tested, before I regain my confidence.

Slow and easy is a good idea

Lamplighter55 Posted at 2018-3-21 04:56
Great narrative - palpitations just reading it! These 'disconnects' though are really an issue, as even the flight record gets cropped off and slightly corrupted. I had 2 flight records show for the same flight as the re-connect registered as a new flight!  So with these it is very hard to nail done the actual cause - if it is from and external source or if it is a bug in the firmware/software and on which device - drone, RC or Go4.

My personal view is that in most cases it is the rubbish on the phone/tablet that is the cause. I stress, it is only a view, based on what goes on with software.
The only other panic mode, brown-trouser event I have ever had was a floppy gimbal on my P3P. A once only event. Apart from this last event, I have always kept apps to the bare minimum and killed all running apps, prior to flight.
The only reason Opera Max got on the phone was because of the phone firmware update. I was stupid for not dealing with it before flight.

Lamplighter55 Posted at 2018-3-21 04:56
Great narrative - palpitations just reading it! These 'disconnects' though are really an issue, as even the flight record gets cropped off and slightly corrupted. I had 2 flight records show for the same flight as the re-connect registered as a new flight!  So with these it is very hard to nail done the actual cause - if it is from and external source or if it is a bug in the firmware/software and on which device - drone, RC or Go4.

Thank you.

Jay W Posted at 2018-3-21 04:59
Great save. I can relate to that dreadful feeling..

Not a good feeling, is it.

I been using Samsung J7 (1 yr) w/ same AOS you have and always flying in Airplane Mode.....never had a disconnect (knock on wood).
Then again I stayed w/ my OEM FW (neglected all updates) and the MP still flying like a champ.
Just hit the anniversary date this month w/ almost 500 flights and had 0 to non issue issue w/ it.

GLAD THAT YOU GOT YOUR BIRD BACK!

mlamb Posted at 2018-3-21 04:49
Are you sure the actual controller disconnected as well?  Something similar happened to me on my second flight with the mavic pro.  The DJI go app said disconnected, screen went black and white I think, and the controller beeped.  I wasn't too far away, maybe 400 feet?  The MP just stayed there in a hover.  The app was dead, but the sticks and buttons on the remote still worked.  Hit the RTH button, and it started climbing and coming back to me.  While on the way back, I killed the app and restarted it, and the DJI go app reconnected.  I ended up aborting the RTH before it landed, I think.

If it happens again, see if you still have control via the sticks, and can initiate at RTH...

I find this a very good post which everybody should need to read and know. When the app disconnects, checking your remote is the first thing you should do, you might still have a connection eventhough you lost your visual.
Thank you for sharing this!

Good recovery     

A CW Posted at 2018-3-21 06:58
Good recovery

Good question earlier in the thread on whether the actual controller has disconnect or just the GO4 app.  I have seen the apps disconnect the the controller have full controll on a number of occasions. In that case you still have control.

Eagle_Eye Posted at 2018-3-21 06:18
I been using Samsung J7 (1 yr) w/ same AOS you have and always flying in Airplane Mode.....never had a disconnect (knock on wood).
Then again I stayed w/ my OEM FW (neglected all updates) and the MP still flying like a champ.
Just hit the anniversary date this month w/ almost 500 flights and had 0 to non issue issue w/ it.

I have never tried Airplane mode. Photography is my hobby, so not likely to try that mode.
Thanks for your comment.

AlansDronePics Posted at 2018-3-21 07:07
I have never tried Airplane mode. Photography is my hobby, so not likely to try that mode.
Thanks for your comment.

Airplane Mode is a option on your phone to turn off you wifi and all app running in the background giving you uninterrupted use of you device meaning no calls/email/text etc. It's not a flight mode for the AC.

LoSBoL Posted at 2018-3-21 06:26
I find this a very good post which everybody should need to read and know. When the app disconnects, checking your remote is the first thing you should do, you might still have a connection eventhough you lost your visual.
Thank you for sharing this!

Looking at the replay of the flight record, there was no stick movement showing between photo and end of record.
I doubt there was any control, because projecting the line back after reconnecting took the origin to the break in control. The drone was just to the right of the Lighthouse and would have been well to the left, had my forward stick command been actioned by the drone. Not only that, the disconnect must have been bi-directional, else the return to home would not have been triggered in the drone. I never used it, it did it itself.
I tried going forward, because after the photo, I wanted to clear the lighthouse safely. There would have been clear space in front of the drone to do so. I planned the shot that way.
I have included the pic I took. Such a poor pic as pics go, so don't hammer me for revealing a delete able. The point being, it was in the first third (rule of thirds) so I could safely go past.

LoSBoL Posted at 2018-3-21 06:26
I find this a very good post which everybody should need to read and know. When the app disconnects, checking your remote is the first thing you should do, you might still have a connection eventhough you lost your visual.
Thank you for sharing this!

And the next thing is to slip into fresh underpants.

WolfgangStiller Posted at 2018-3-21 07:04
Good question earlier in the thread on whether the actual controller has disconnect or just the GO4 app.  I have seen the apps disconnect the the controller have full controll on a number of occasions. In that case you still have control.

Good point. I have now answered that in the earlier comment about this.
Thanks for your interest.

AlansDronePics Posted at 2018-3-21 07:07
I have never tried Airplane mode. Photography is my hobby, so not likely to try that mode.
Thanks for your comment.

You might been mixing Fixed wing mode which is flight mode for the AC with Airplane mode for the phone.

AlansDronePics Posted at 2018-3-21 07:30
And the next thing is to slip into fresh underpants.

Another thing to pack in the fly more combo bag

AlansDronePics Posted at 2018-3-21 07:29
Looking at the replay of the flight record, there was no stick movement showing between photo and end of record.
I doubt there was any control, because projecting the line back after reconnecting took the origin to the break in control. The drone was just to the right of the Lighthouse and would have been well to the left, had my forward stick command been actioned by the drone. Not only that, the disconnect must have been bi-directional, else the return to home would not have been triggered in the drone. I never used it, it did it itself.
I tried going forward, because after the photo, I wanted to clear the lighthouse safely. There would have been clear space in front of the drone to do so. I planned the shot that way.

I don't know if the flight recorder from the app would still function if the appview disconnects. Or did you by change refered to the flight record from the craft itself?
I'm not saying that you might still have had a connection with the remote, but it was a very good post to check the remote first if the App disconnects, in the line of 'any thoughts that would help someone else'  

I can only imagine the stress. I am glad it all worked out and the bird is back. Well done.

Eagle_Eye Posted at 2018-3-21 07:13
Airplane Mode is a option on your phone to turn off you wifi and all app running in the background giving you uninterrupted use of you device meaning no calls/email/text etc. It's not a flight mode for the AC.

I am most grateful to you for that info. I confess I saw it mentioned and disregarded it. I thought why would I want to fly it like an aeroplane? Thinking 'photography' Hovering is what I do. Missed ot there, big time.
Thanks.

G_Sig Posted at 2018-3-21 07:41
You might been mixing Fixed wing mode which is flight mode for the AC with Airplane mode for the phone.

I will check my settings, but unlikely if you read the chain of events.
Good point though.

LoSBoL Posted at 2018-3-21 07:46
I don't know if the flight recorder from the app would still function if the appview disconnects. Or did you by change refered to the flight record from the craft itself?
I'm not saying that you might still have had a connection with the remote, but it was a very good post to check the remote first if the App disconnects, in the line of 'any thoughts that would help someone else'

As I said, I saw no stick movement after the pic, when replaying the second or so after.
If you are right, why would Go Hoe kick in? If it is receiving, there would be no need to return to home.

Marian Posted at 2018-3-21 07:47
I can only imagine the stress. I am glad it all worked out and the bird is back. Well done.

Thank you.

LoSBoL Posted at 2018-3-21 07:41
Another thing to pack in the fly more combo bag

It is a bit tight in there.  

AlansDronePics Posted at 2018-3-21 08:06
As I said, I saw no stick movement after the pic, when replaying the second or so after.
If you are right, why would Go Hoe kick in? If it is receiving, there would be no need to return to home.

I wasn't questioning if you still had a connection with the remote. Just loved the tip made by mlamb. which should be nr.1 on the checklist when confronted with an app disconnect.

AlansDronePics Posted at 2018-3-21 05:19
My personal view is that in most cases it is the rubbish on the phone/tablet that is the cause. I stress, it is only a view, based on what goes on with software.
The only other panic mode, brown-trouser event I have ever had was a floppy gimbal on my P3P. A once only event. Apart from this last event, I have always kept apps to the bare minimum and killed all running apps, prior to flight.
The only reason Opera Max got on the phone was because of the phone firmware update. I was stupid for not dealing with it before flight.

"Opera Max got on the phone was because of the phone firmware update."

This is one of things that scared me off of using a Samsung Galaxy 8 or 9.
Unknown software getting loaded by firmware updates or changes to other software through "pushed services".

Natuarally with non-DJI product, there is no testing of conflicts between GO4 App, Android OS, Samsung Firmware, and built-in App updates.

All mute, being my CS Ultra was flaky from get go.  

"   Any thoughts that would help someone else? "

Need to clarify something.  When you lost contact with your drone - Was Remote Controller also showing it was no longer connected or only the GO app on your smartphone?


Without being there.  
I would have immediately tried to initiate a RTH.  
If that failed, immediately rebooted Remote Controller, while moving closer or changing position,.
Then tried another RTH if drone was still hovering.

LoSBoL Posted at 2018-3-21 08:19
I wasn't questioning if you still had a connection with the remote. Just loved the tip made by mlamb. which should be nr.1 on the checklist when confronted with an app disconnect.

No, I didn't think you were questioning. I agree, with you it is a good tip, however, just consider this:-
If the drone is out of sight at the time, lets be honest, it usually is or hard to find again when you look up, how will you know if it is responding to RTH?
If the operator has a disconnect, even if just from drone back, where is it now headed?
Will RTH actually function reliably, after all, something bad has happened.
Obviously it is up to the drone operator to make his own decision what he/she does. My priority was to regain control ASAP.
Based on other users flight issues, fly-aways etc, I try and have some sort of plan to solve the problem, rather than waiting till it happens and trying to think of one. Doesn't everyone do that?
I will be quite honest, I am so scared the drone is going to fall out of the sky, I deviate off course to go past rather than over anything it might drop on. I live on a small island, so there is a lot of sea around me. It took several days of planning to fly out to a ship wreck.  See video
I am very risk averse.

AlansDronePics Posted at 2018-3-21 08:41
No, I didn't think you were questioning. I agree, with you it is a good tip, however, just consider this:-
If the drone is out of sight at the time, lets be honest, it usually is or hard to find again when you look up, how will you know if it is responding to RTH?
If the operator has a disconnect, even if just from drone back, where is it now headed?

Yes, I agree, its good to know what to do and expect if your connection fails, I even made a topic for the Mavic Air so you can expect what happens when it does: https://forum.dji.com/thread-139795-1-1.html (A Mavic Pro flies straight to home, a Mavic Air retraces its path for 60 seconds before going returning straight to home)

I don't know how you can see on the display of a Mavic Pro remote if you are still connected, somebody with a Mavic Pro could answer that. For a Mavic Air there is a green led that tells you if the Aircraft and Remote are connected.
Initiating a RTH in such cases should work, and the remote starts beeping when you hit that RTH button. So I would expect it would come back from that point.

HedgeTrimmer Posted at 2018-3-21 08:22
"Opera Max got on the phone was because of the phone firmware update."

This is one of things that scared me off of using a Samsung Galaxy 8 or 9.

That is so true. If I could afford it, I would buy a CrystalSky because it would be a dedicated device free from Samsung bloatware.
The advantage of a super bright screen is huge for me as a happy-snapper. The good thing about Samsung screens are that they are brighter than most phones.
I am unlikely to upgrade from the J7, because the screen is so bright, the battery is replaceable and the interconnection of apps and data harvesting that goes on is just unacceptable to me.
I respect others choices though.

HedgeTrimmer Posted at 2018-3-21 08:30
"   Any thoughts that would help someone else? "

Need to clarify something.  When you lost contact with your drone - Was Remote Controller also showing it was no longer connected or only the GO app on your smartphone?

OK, happy to touch on the points again.
The remote showed disconnect and telemetry did not change with stick thrashing. Also go4 app showed it.
Have a look at my reasoning below about the RTH issue. I accept that if you were flying, what you do is your best judgement. I respect that.

AlansDronePics Posted at 2018-3-21 08:58
OK, happy to touch on the points again.
The remote showed disconnect and telemetry did not change with stick thrashing. Also go4 app showed it.
Have a look at my reasoning below about the RTH issue. I accept that if you were flying, what you do is your best judgement. I respect that.

Thanks for clarifying that.

This is strictly a side thought, to go into DJI suggestion box.

What if there was a separate compact Remote Controller a person could use that would send out a boosted Return to Home signal?   

Device dedicated to one thing, with no issues of software / firmware upgrades.  Essentially, a panic-button wrist-watch.  

LoSBoL Posted at 2018-3-21 08:48
Yes, I agree, its good to know what to do and expect if your connection fails, I even made a topic for the Mavic Air so you can expect what happens when it does: https://forum.dji.com/thread-139795-1-1.html (A Mavic Pro flies straight to home, a Mavic Air retraces its path for 60 seconds before going returning straight to home)

I don't know how you can see on the display of a Mavic Pro remote if you are still connected, somebody with a Mavic Pro could answer that. For a Mavic Air there is a green led that tells you if the Aircraft and Remote are connected.

I have no knowledge of the MAir. Sounds like a great advance in getting out of the mire. I love it.
The display shows a large 'Connecting' and an an animated symbol.
Yes, RTH and everything else would probably work if it wasn't showing Disconnected.
So, if it is disconnected, what would everyone do?

HedgeTrimmer Posted at 2018-3-21 09:07
Thanks for clarifying that.

This is strictly a side thought, to go into DJI suggestion box.

Sounds like a great idea for DJI to make something else to sell.  As a gadget freak, the idea appeals to me.
I think the reality is different though. If the drone is not receiving the coded signal and it didn't fail because of range issues, you could power the booster from the national grid and the drone would still not recognise it. (A bit of exaggeration on the power demands, but you know what I mean.)