Hello,

First of all, thank you anyone trying to help people on this forum.

I'm a new drone pilot with little experience. I have had DJI Spark before but besides some quick shots and short flights around my house(Spark cannot make long flights anyways), I didn't use it too much or very often to have a great deal of experience. But still, I'm not having diffuculties navigating a drone in the air, I'm not that newbie.


I've purchased Mavic 3 classic last week and I love it. I'm not a professional, I got the drone for hobby/amatour flights. I also have piloting license for the drone so I'm legally covered.

Today I almost lost the drone and I was really scared. I believe I've dodged a bullet. But I still don't understand why/how and how I can prevent same thing in the future.

I was at the shore and there is an island 6-7 kilometers away from the shore. Since my drone have 8km RC range(EU regulations), I thought I could make it without issues and send the drone on the island to get some nice shots. And even if RC gets disconnected, it will return to the home point, right? After all it was a sunny day with great and clear weather and low wind. So I started flying it to that island, at 70m altitude. I also wanted to speed things up a little bit by using it in sports mode(also wanted to see how fast it can fly). After going 2000 meters, RC connection is lost momentarily. It took only around 5 secs before reconnecting(dropped connection suddenly and before dropping connection, it was showing full reception). After reconnecting, it was at full reception again. I have no idea what happened and why since there were no boats around or anything that could block the signal after all. It is open sea. But the real issue happened right after that. After reconnecting, suddenly RC started beeping indicating GPS signal is lost. There are no clouds. Great weather, there is nothing I can think of to cause loss of GPS signal. And at that point, RC started disconnecting/connecting again. I have managed to turn the drone in opposite direction and started pushing forward. I got lucky and it moved towards me. After a while, RC signal stabilised again and GPS signal is captured again. After that point, I had no issues returning it back to me and I was able to fly for another 20 mins without any issues(I kept it close to me of course).

Now I have some questions;
1. What happened, why I lost GPS signal? I'm not obsessed with RC signal lost, it might be normal and even my cellphone might have caused it, but losing GPS signal is a big problem. It could land on water because of that.
2. Maybe going too fast(at max speed with sports mode for around a minute) caused GPS signal loss?
3. If there is GPS signal, it should return to home point on RC signal loss. If there is no GPS signal, it should hover wherever it is on RC signal loss instead of landing immediately(it can try to land on low battery and there is nothing to be done at this point, but I want it to hover until RC signal is restored instead of landing if there is not GPS signal so I can try to save it).


Thank you so much for sharing your experience in advance.

Until you are familiar with the drone DON'T try flights to great distance over water, experiment over dry land well away from people.  Quoted range is in ideal conditions.

Regarding "it can try to land on low battery and there is nothing to be done at this point", strictly speaking that is incorrect, the manual says "The aircraft will land automatically if the current battery level can only support the aircraft long enough to descend from its current altitude. Auto landing cannot be canceled but the remote controller can be used to alter the direction and the speed of descent of the aircraft during landing.''  and, though the manual is not well worded, it implies that you can even make the drone climb slowly ..... whilst there is sufficient power.

I know of no option to choose what happens when you lose BOTH GPS and connection. I wish you the best of luck in trying to get DJI to implement it.

Just cause it says no GPS and say signal lose doesn't mean your drone will go out of control or anything. It will always come back to home as long as there is enough battery. I have my drone lose signal and GPS and it always come back. These drone are so advanced you can never lose it if you don't fly like a idiot. Most people who lose their drone are those who ignore low battery return home and tried to return from like 4-5 miles away with 40% battery. You will not make it. Lol. Also don't fly over open water, that is how you lose your drone. Your drone will always return home, I think you over panic cause you are new and think losing signal/GPS your drone won't come back. It will come back.

djiuser_zKR5HFX3a2EC Posted at 5-22 14:46
Just cause it says no GPS and say signal lose doesn't mean your drone will go out of control or anything. It will always come back to home as long as there is enough battery. I have my drone lose signal and GPS and it always come back. These drone are so advanced you can never lose it if you don't fly like a idiot. Most people who lose their drone are those who ignore low battery return home and tried to return from like 4-5 miles away with 40% battery. You will not make it. Lol. Also don't fly over open water, that is how you lose your drone. Your drone will always return home, I think you over panic cause you are new and think losing signal/GPS your drone won't come back. It will come back.

I have my drone lose signal and GPS and it always come back.
Not true.
Your drone cannot return home if it has actually lost GPS.

Also don't fly over open water, that is how you lose your drone.
Why do you say that?
FLying over open water is safer than flying over solid ground.

Now I have some questions;
First, there are a few problems with your description of what you think happened.
To get proper help you need to post the recorded flight data so people can see what really happened.

Go to: https://www.phantomhelp.com/LogViewer/Upload/
... where you'll find instructions to upload the data to that site and it will give a report
For help interpreting the data you can post a link for the report here.
Or just post the .txt file.

1. What happened, why I lost GPS signal?
Did it actually lose GPS?
Lets see the recorded flight data.

I'm not obsessed with RC signal lost, it might be normal and even my cellphone might have caused it, but losing GPS signal is a big problem. It could land on water because of that.
No, your cellphone couldn't have caused anything.

2. Maybe going too fast(at max speed with sports mode for around a minute) caused GPS signal loss?
No ... going too fast doesn't cause GPS loss, but it does drain the battery faster.

3. If there is GPS signal, it should return to home point on RC signal loss. If there is no GPS signal, it should hover wherever it is on RC signal loss instead of landing immediately(it can try to land on low battery and there is nothing to be done at this point, but I want it to hover until RC signal is restored instead of landing if there is not GPS signal so I can try to save it).
If you lose GPS the drone is still fully controllable.
But it cannot hold position or RTH.

hopefully you have such coverage in your country, DJI Care Refresh.  i suggest you get a least a year if available to you.  it's good insurance.

Stop flying further than you can handle.  It is just asking for trouble.  

Labroides Posted at 5-22 15:11
Now I have some questions;
First, there are a few problems with your description of what you think happened.
To get proper help you need to post the recorded flight data so people can see what really happened.

Thank you for your reply.

Here is the report: https://www.phantomhelp.com/LogViewer/6JNTJRY3HAK8HHIU367M/

Labroides Posted at 5-22 15:11
Now I have some questions;
First, there are a few problems with your description of what you think happened.
To get proper help you need to post the recorded flight data so people can see what really happened.

Thank you for your reply.

Here is the report: https://www.phantomhelp.com/LogViewer/6JNTJRY3HAK8HHIU367M/

1. What happened, why I lost GPS signal?
Your satellite numbers dropped off quite rapidly from about 20 to 8-10 and the flight controller's confidence in the data it was getting from those 8-10 was low.
This is the effect that you see with GPS jamming.
Jamming of GPS is known from a few places in your country:
https://gpsjam.org/?lat=39.43985 ... 4.8&date=2023-05-21

I'm not obsessed with RC signal lost, it might be normal and even my cellphone might have caused it, but losing GPS signal is a big problem. It could land on water because of that.
If you lose signal, the drone will initiate your failsafe action (the default setting is RTH).
If you lose GPS, you still have full control, but the drone won't hold position and can drift on the wind.
If you lose GPS and lose control signal, the drone will autoland where it is.
Lucky for you the loss of signal was only for one second.

If you are out over water when that happens, that's a big dose of bad luck.
In most places this would be very rare, but in your part of the world, not so rare.
So it would be a good idea to be careful before flying long distances over water.

Labroides Posted at 5-23 02:35
1. What happened, why I lost GPS signal?
Your satellite numbers dropped off quite rapidly from about 20 to 8-10 and the flight controller's confidence in the data it was getting from those 8-10 was low.
This is the effect that you see with GPS jamming.

Thank you so much for sharing this link and explaining in detail. Now I know what happened and I think it is best that I won't fly too far away in water where RC signal could be lost.

This is a question for Bartuc only, please no one else answer it. I want to see if Bartuc can work out the answer, doing so might make the ' lesson' 'stick' better.

Bartuc, have a look at the artificial-horizon/attitude-indicator, the circle with a blue segment in it.
In the replay on PH, looking at that indicator and the reported speeds what do you notice about the outbound and return portions of the flight?
I had my suspicions almost as soon as the drone started the out bound movement but it was confirmed as soon as reliable data commenced on the return. There is similar information available "live" in the app as the drone is being flown.


So far I have not looked at any other data from the flight log but I think you were lucky that this problem arose and prevented the flight to the island.
I think that if you had managed to reach the island you probably WOULD NOT have got your drone !
The problems your encountered early on in that attempt saved your drone.

Sean-bumble-bee Posted at 5-23 03:02
This is a question for Bartuc only, please no one else answer it. I want to see if Bartuc can work out the answer, doing so might make the ' lesson' 'stick' better.

Bartuc, have a look at the artificial-horizon/attitude-indicator, the circle with a blue segment in it.

I believe that indicates a tailwind while going outbound. Which means I'd probably run out of power on my way home. But I had confidence in DJI fly app about not letting me go that far away and I was thinking that possibly I won't make it to the island and I'd have to come back because of low battery on my way to the island, but due to head wind, I understand I'd run into problems. Still, I can see that flying on the water that far away is never a good idea. Renting a boat to go to that island(or any island) is way better and cheaper than losing the aircraft

Labroides Posted at 5-23 02:35
1. What happened, why I lost GPS signal?
Your satellite numbers dropped off quite rapidly from about 20 to 8-10 and the flight controller's confidence in the data it was getting from those 8-10 was low.
This is the effect that you see with GPS jamming.

Is there a way to change this behaviour?

If GPS and RC signals both lost, it should hover until battery is critical and only with critical battery it should land. That would give me a shot on saving the drone in the future. Is it possible to do?

We agree, a tail wind, Airdata indicates 11mph NE to SW.
Your go home height was set to 328 ft, over the sea that height is unnecessary and there is a fair chance an RTH would have sent the drone up into stronger winds.
I don't think you drone entered RTH during this phase of the flight, its height didnt change significantly.
I do not know if the low battery RTH takes encountered wind into consideration.

I am not criticising you, merely pointing out what I think are mistakes that are risky.

I think this video is an absolute cracker of a lesson

If you do not have JJB*'s FRAP but have a windows computer you can download CsvView from
https://datfile.net/CsvView/downloads.html
and use it to process the Phantomhelp csv.
I get the attached

Sean-bumble-bee Posted at 5-23 07:13
We agree, a tail wind, Airdata indicates 11mph NE to SW.
Your go home height was set to 328 ft, over the sea that height is unnecessary and there is a fair chance an RTH would have sent the drone up into stronger winds.
I don't think you drone entered RTH during this phase of the flight, its height didnt change significantly.

Thank you so much. If it wasn’t for you, I’d never realise this danger. In the video it is clear that rth battery doesn’t account for the wind. I would possibly end up in water with no battery left.

Hi,

Had a look at your flightlog too.

GPS jamming is seen in the log looking at the Lattitude and Longitude GPS recordings,
when GPS is jammed the positions are random or at a different positions than where the craft is actually flown.

This is not seen ion your log.

At record 1249 at 4m15.2s in flight Lat Lon data:  LAT = 40.937209 , LON = 29.081489.
Distance to home 1974.7 meter.  Distance is calculated from actual postion to HP.

From 4m15.2s to 6m25.6s no changes to the LAT LON positions. You must have seen this on the fly app screen, as the distance did not change!
At record 1895 (6m25.6s) LAT LON data is recording again actual postion, now distance to HP = 1669.8 meter.
In this period 8, 9 or 10 sats with 2 for 'quality' (range = 0-5).  Value 0 or 1 is normally drone into ATTI mode, so your were kind of lucky there.

Many warning " GGPS sinyali zayf. Hava duru dengesiz. Dikkatli u = GPS siignal is weak. The air is unstable. Careful u (funny google translate)

Remaining flight time in the FlyApp is not corrected for wind...it uses the current battery usage to extrapolate for the rest of the flight....
So flying away from HP with tail wind, and returning when the app says so to do...flying back wind head wind can be tricky, does my drone reach HP or not....

In the log 2x a short connection loss (both 1 second). The downlink value (range bad 0 - 100 good ) at that point just 18.  (see smaller chart)
Has nothing to do with your GPS.

In the Google Map chart the 2 positions where in bewteen the LATLON data did not change.
If there was GPS jamming, to me not logic to have in only there   :-)  [ plus 2 great straight lines.... ]

For Drone safety...loosing connection to the drone and drone is for some reason in ATTI mode > drone will autoland, safer * than drifting away on the wind uncontrolled.
* asssuming that before loosing connection drone was flying in safe airspace.

For the analist under the readers ; Field "OSD.isGPSUsed" is FALSE with "Field OSD.gpsLevel"  = 2. GPS not in use with a 0 = ATTI mode.
This is the first time i see that the LATLON data is not changing with a 2. Normally even in ATTI mode due to compass errors GPS is not used but LATLON data is recording actual positions.

cheers
JJB   [ Charts by FRAP ; the 'best' software for flightlog analysis ]

Good catch about the ATTI mode JJB*.

Bartuc Posted at 5-23 06:49
Is there a way to change this behaviour?

If GPS and RC signals both lost, it should hover until battery is critical and only with critical battery it should land. That would give me a shot on saving the drone in the future. Is it possible to do?

No ... that's the way DJI have programmed it and there are no options to change it.

Hello, I lost my drone. Connection failed during flight, and the last location has my drone seen is not correct. I looked at everywhere but still haven't find it. What should I do? I'm really upset. It haven't return the home and it's been 2 hours.

Derin Güngör Posted at 4-7 12:24
Hello, I lost my drone. Connection failed during flight, and the last location has my drone seen is not correct. I looked at everywhere but still haven't find it. What should I do? I'm really upset. It haven't return the home and it's been 2 hours.

See my post (#5) above for instructions to post your flight data.
That might help understand what happened to your drone.

Derin Güngör Posted at 4-7 12:24
Hello, I lost my drone. Connection failed during flight, and the last location has my drone seen is not correct. I looked at everywhere but still haven't find it. What should I do? I'm really upset. It haven't return the home and it's been 2 hours.

Hi, Derin. We're sorry to know the incident happened to your unit. If your unit is still within the warranty period, we suggest contacting our team at https://www.dji.com/support to set up a flyaway case. After finalizing the request, we will ask you to provide specific files to help the investigation. Thank you for your understanding and support.

You were lucky! One possibility could be poor battery contacts, this could explain the problems starting in sport mode (high power demand) Cheers

Interesting.     I had my Mavic 3 go into ATTI mode a few times but luckily never over water.
I was flying a airport infrastructure mission  & cell tower transmission coming from a cell tower by the airport terminal I flew by during the operations sent my M3 into ATTI, I learned very quickly to take into account for any near by Radio obstruction. because my expreince with flying a Mavic3 in ATTI mode is like trying to fly a hockey puck on ice. and if you do not have a good visual on your aircraft its going to be extremely difficult to control it to get it back if you can not see it.  So that my only advice I have for that reason, keep your UAV in VLOS.  Now days on commercial missions I always use a arc strobe light on my drone even in the day time so I can pick up the visual on it quickly .  
I am glad that this had a happy ending for you
Happy flying