Lost my drone, it didn't return.

[jedrekd]

Yesterday I went to fly my DJI Air 2S at altitude over 300 meters and 1,2 km away over the ocean in Seixal on Madeira and I visual connection with my drone on my mobile. I pressed Return to Home twice to initiate RTH mode, I could hear 2 beeps signal on the controller for a while then it turned into a single beep signal and I waited and waited and waited and the drone never returned. What could have happened? I lost signal many times before and it was always able to make it back by itself and only this time it didn't make it. Then I saw a drone over my head but it was flying as if it was controlled by someone so it wasn't my drone unless someone could intercept it somehow. Is it even possible? Or maybe some authorities intercepted it because I violated the max altitude of 120 ft. Not sure if they are allowed to just steal somebody's property. I am trying to understand what could have happened an learn something from this experience. Are there any logs in the app on the phone that could shed some light into what happened there? Not to mention that I lost a very good drone worth a lot of money and I feel quite sad about it.

 

[GFields]

If you had already lost connection, hitting RTH would do nothing. However, it should have returned on its own after losing connection.

 

[slup]

At 300m height out over a ocean the wind speeds can be very, very different than where you are... & if you flew out with a tail wind it's a real possibility that your drone didn't come home due to

A: it couldn't counter a strong headwind & instead drifted backwards...
or B: it couldn't reach a enough high ground speed in a strong headwind & the battery ran out before reaching back.

Another common scenario we have seen here at the forum is that you flew out before a HP was recorded... it was then later recorded along the flight path... out over the ocean, & it returned to that spot & drowned.

For logs...

Go here --> DJI Flight Log Viewer | Phantom Help & read up how you retrieve the logs from the screen device you flew with, then upload the log there... & then if you want help to interpret it, share the link they provide here in this thread in a new post.

 

[mavic3usa]

No idea but I've heard that pressing RTH twice can sometimes start it and then cancel it, maybe?

When you said lost the connection, did you lose visual but still maybe had a connection with your remote controller?

What are your RTH settings like, do you have it set to hover when you lose connection where it just sits there until the battery gets super low....at which point I would think it would start to come home perhaps. But being that high and far away....maybe it didn't make it. Or it flew to another home point which is over your head and back to camp.....

That drone that flew over your head, did it look like yourself? Or can you not tell when it was flying at nearly 1,000 feet....my Evo 2 Pro I could barely see all that orange at that high overhead.

 

[Yorkshire_Pud]

Ah @mavic3usa beat me to the comment abiut pressing RTH twice.

That said, what was the battery percentage whem you lost contact?
If above the low battery RTH threshold then even if you did cancel an ongoing RTH the low battery RTH should have kicked in.
However if the battery percentage was below the low battery RTH threshold and you did cancel the RTH then your drone may have gone swimming.

"Then I saw a drone over my head but it was flying as if it was controlled by someone so it wasn't my drone..." what was it doing?

Posting the flight log as suggested by @slup may provide some answers

 

[Meta4]

Then I saw a drone over my head but it was flying as if it was controlled by someone so it wasn't my drone unless someone could intercept it somehow. Is it even possible? Or maybe some authorities intercepted it because I violated the max altitude of 120 ft. Not sure if they are allowed to just steal somebody's property.

None of those scenarios are possible or likely.

I am trying to understand what could have happened an learn something from this experience. Are there any logs in the app on the phone that could shed some light into what happened there?

There are several possibilities.
If you want to find out, you need to post your flight data and it will solve the mystery.

There are a couple of options ...

1. 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 on the flight data.
Come back and post a link to the report it provides and someone might be able to analyse it and give you an understanding of the cause of the incident.
or
2. Just post the .txt file here
or
3. If you use Airdata, you can view the flight data on Airdata and post a link for the Airdata report

 

[RodPad]

@jedrekd
Post your flight info, many here will help, if you got questions.

That's it for me.
To all that post's later, I hope this thread is mostly facts..

Rod ..

 

[Telthecelt]

Yesterday I went to fly my DJI Mavic 2S at altitude over 300 meters and 1,2 km away over the ocean in Seixal on Madeira and I lost signal with my drone. I pressed Return to Home twice to initiate RTH mode, I could hear 2 beeps signal on the controller for a while then it turned into a single beep signal and I waited and waited and waited and the drone never returned. What could have happened? I lost signal many times before and it was always able to make it back by itself and only this time it didn't make it. Then I saw a drone over my head but it was flying as if it was controlled by someone so it wasn't my drone unless someone could intercept it somehow. Is it even possible? Or maybe some authorities intercepted it because I violated the max altitude of 120 ft. Not sure if they are allowed to just steal somebody's property. I am trying to understand what could have happened an learn something from this experience. Are there any logs in the app on the phone that could shed some light into what happened there? Not to mention that I lost a very good drone worth a lot of money and I feel quite sad about it.

It's a good idea to check the map for restricted areas out from the runways of airports, which in the case of Madeira is bound to include areas over the ocean as well as the land. I've been to the island a few times and I am aware that airlines count the airport as being one of the more challenging ones to land in, sometimes requiring the aborting of a first attempt, a circle over the sea and another go (something I have experienced). Flying the drone at more than twice the altitude even over the sea, is perhaps not the most wise thing to do. If a drone distracted my pilot (or worse) that would make me feel quite sad.

 

[jedrekd]

If you had already lost connection, hitting RTH would do nothing. However, it should have returned on its own after losing connection.

That's not true. Many times I pressed the H button on the controller after I lost visual signal on my phone (screen went black and a red text said Device not connected) and the drone always returned back.

 

[jedrekd]

It's a good idea to check the map for restricted areas out from the runways of airports, which in the case of Madeira is bound to include areas over the ocean as well as the land. I've been to the island a few times and I am aware that airlines count the airport as being one of the more challenging ones to land in, sometimes requiring the aborting of a first attempt, a circle over the sea and another go (something I have experienced). Flying the drone at more than twice the altitude even over the sea, is perhaps not the most wise thing to do. If a drone distracted my pilot (or worse) that would make me feel quite sad.

What did you want to say with your comment? I don't understand. As I said, I was flying over Seixal so on the opposite site of the island. Around the airfield (Machico, Santa Cruz) the app will not even let you start your drone but what does this have to do with the drone not returning back?

 

[jedrekd]

No idea but I've heard that pressing RTH twice can sometimes start it and then cancel it, maybe?

When you said lost the connection, did you lose visual but still maybe had a connection with your remote controller?

What are your RTH settings like, do you have it set to hover when you lose connection where it just sits there until the battery gets super low....at which point I would think it would start to come home perhaps. But being that high and far away....maybe it didn't make it. Or it flew to another home point which is over your head and back to camp.....

That drone that flew over your head, did it look like yourself? Or can you not tell when it was flying at nearly 1,000 feet....my Evo 2 Pro I could barely see all that orange at that high overhead.

That's what happened. I simply had a black screen from the drone cam on my phone and pressed H button, like many times before. I didn't change any settings so I guess they are default which is RTH I guess since it returned many times before. That drone I saw indeed looked like mine.

 

[jedrekd]

I retrieved the flight logs from my phone and here's the logs. It doesn't say much, though. The last line says "RC not connected to mobile device".

UPDATE
I now see in line 5 it says "Home Point updated. RTH altitude adjusted to 30 m." I don't know why it changed the RTH altitude from 100 to 30. Does the drone still have the proximity sensors enabled while returning home in fail safe mode? If not maybe it hit a rock and fell into the water? I don't know why it changed the RTH altitude by itself, though. It doesn't sound right to me.

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

 

[jedrekd]

Ah @mavic3usa beat me to the comment abiut pressing RTH twice.

That said, what was the battery percentage whem you lost contact?
If above the low battery RTH threshold then even if you did cancel an ongoing RTH the low battery RTH should have kicked in.
However if the battery percentage was below the low battery RTH threshold and you did cancel the RTH then your drone may have gone swimming.

"Then I saw a drone over my head but it was flying as if it was controlled by someone so it wasn't my drone..." what was it doing?

Posting the flight log as suggested by @slup may provide some answers

The battery was at about 80% for sure because it was at 100% when I lifted off and it was my only flight.

 

[slup]

I retrieved the flight logs...

Well... you apparently neither lost the control or the video connection...


From the message event log it's clear that your screen device got disconnected from the RC... so the RC was still connected to the drone, meaning that the drone still was fully controllable from the RC.

So if you pushed twice on the RTH button you first started the RTH... then cancelled it on the second push & left the drone just hovering out there over the ocean.

Once you either turned off the RC or in another way disconnected the RC from the drone it would have gone into RTH automatically... if you instead was just waiting, the battery would later be depleted down to the low battery RTH instead. All this could have taken a rather long time as you had 78% battery when the screen device was disconnected from the RC.

According to the log & what was recorded before the screen device disconnected... nothing indicate any failure, overly strong wind or a late recorded HP.

My bet is that the drone actually returned to the recorded HP... but much later than you expected.

This was the wind speeds & directions



And this the most important telemetry from the log just in the end... the chart marker is placed just where the log ends, the values from that point for the graphs is shown in the legend below the chart.

The drone was just hovering out there 1476ft above the take off location...

(Click on the chart to make it larger)

 

[jedrekd]

So if you pushed twice on the RTH button you first started the RTH... then cancelled it on the second push & left the drone just hovering out there over the ocean.

On DJI Mavic 2S you active RTH by pressing and holding the H button on the controller, just like you power on your drone - you press once and press another time and hold it. This is how this drone works. I read it in the manual and this is what I always did in the past. If you do this, the controller starts double beeping just like in this case and it was double beeping for around 30 seconds and it switched to a single beep after that. So I did not cancel RTH, it was flying back home but something caused it not to return home. I waited over 40 minutes which is way more than the battery would have lasted even when hovering over the ocean, which means that it fell into the ocean.

Once you either turned off the RC or in another way disconnected the RC from the drone it would have gone into RTH automatically...

That's what I would expect but it didn't happen.

My bet is that the drone actually returned to the recorded HP... but much later than you expected.

As I said, I waited more than 40 minutes which is more than the batter would have lasted but it never returned.

 

[Yorkshire_Pud]

That's not true. Many times I pressed the H button on the controller after I lost visual signal on my phone (screen went black and a red text said Device not connected) and the drone always returned back.

If you lost control connection then the RTH button does nothing. That is simple fact, it can't because the controller has no way of communicating with the drone.
If you lost the JUST video signal that is a different matter because you still have control communication between the drone and the controller.
You said " ...... Madeira and I lost signal with my drone ....." and it is a reasonable assumption to assume you meant control connection so what Gfields said was correct.

Home Point updated. RTH altitude adjusted to 30 m.

There is nothing in the log to suggest that the RTH was ever anything but 30m, look at the csv downloaded from phantomhelp and the column HOME.goHomeHeight [ft]. It is 98.4ft for the whole column.
If it was 100m in a previous flight then I would guess you accidentally changed the height before the drone started to record a log. Unfortunately that is very easy to do ...... as I know from personal experience.
One other thought occurs, could you have set the drone/app to use imperial units?

altitude over 300 meters and 1,2 km away

more like over 440m and 1.5km away.

The last line says "RC not connected to mobile device".

Which would normally mean
a) the phone had disconnected from the controller but
b) the controller was still controlling the drone.
What model of controller do you have?
It is therefore possible that your double press of the RTH button started and then cancelled the RTH.

When the drone stopped on its outbound flight it looks at if there was a side wind but I doubt that it was strong enough to cause the drone problems.

With the battery percentage and the possible cancelling of the RTH I think it is possible that the drone will have hovered until low battery RTH kicked in.

Given the drone's distance and height a straight forward RTH commanded by you would, I think, have started a "smart RTH", in which drone descends at 14deg. If my maths is correct it would have arrived over the home point at a height of around 64m and then descended vertically. Whether or not a low battery RTH uses "smart RTH" I have no idea. @slup?
If it doesn't then your drone will have arrived over the home point at a height of around 444m and then descended vertically.

Does the drone still have the proximity sensors enabled while returning home in fail safe mode?

It can do but you should know the answer to that question already, it's covered in the manual. I do not know if OA can be switched off but I would assume it can.
However, thoughts of OA raise another question, where was the sun and how low was it?
If the drone was RTH'ing into the sun and OA was on then it has been known to cause the drone to detect an obstacle. You should read the manual to check what the drone's behaviour is if it thinks there is an obstacle in the way, especially when it is flying at or near the set maximum height ..... which your drone was.... at least around the start of your problems.

Then I saw a drone over my head but it was flying as if it was controlled by someone so it wasn't my drone unless someone could intercept it somehow.

Again this is covered in the manual.
RTH places constraints on what controller commands the drone will follow during the various phases of the RTH.


Final point, I think. If the drone did get back to above the home point and did have OA on then I suspect, note suspect, that HORIZONTAL OA will be disabled during the vertical descent but I am not sure about that.
Others will have to address that point. @slup??

Landing protection will still work but with no screen device you will not have seen any messages. Any vibrations from the controller would not have had any meaning and I have no way of knowing what audible messages, if any, the controller gives out because I am deaf.

My suggestion, look around/underneath where you saw the 'other' drone and or describe its flight path.

PS Perhaps @slup can confirm this but I think logs DO NOT tell us whether or not OA is switched on, if I am correct I think that that is a major oversight on DJI's part.

 

[jedrekd]

If you lost control connection then the RTH button does nothing. That is simple fact, it can't because the controller has no way of communicating with the drone.
If you lost the JUST video signal that is a different matter because you still have control communication between the drone and the controller.
You said " ...... Madeira and I lost signal with my drone ....." and it is a reasonable assumption to assume you meant control connection so what Gfields said was correct.

Sorry, I misspoke, I lost camera visibility on my phone but the controller was still connected with my drone.

It is therefore possible that your double press of the RTH button started and then cancelled the RTH.

You active RTH by pressing and holding the H button on the controller, just like you power on your drone - you press once and press another time and hold it. I read it in the manual and that's what I always did in the same situations many times in the past. This is a video that demonstrates this.

When I got a black screen I pressed and held the H button and the controller started beeping, just like on a video. This is what this button is meant for - it's meant to be used when you can't control your drone in situations when you loose camera view from your drone and you can't see it physically in the sky.

 

[slup]

@jedrekd ... you deleted your last post?

But your version about double tapping the RTH button is how you activate RTH on a MA2s isn't correct... below is from the manual.

Once again... you started the RTH but then cancelled it on the second button push, & left the drone hovering.

 

[jedrekd]

@jedrekd ... you deleted your last post?

But your version about double tapping the RTH button is how you activate RTH on a MA2s isn't correct... below is from the manual.

Once again... you started the RTH but then cancelled it on the second button push, & left the drone hovering.

View attachment 170351

If I canceled RTH then the controller would have stopped beeping but it didn't stop beeping.

 

[GFields]

That's not true. Many times I pressed the H button on the controller after I lost visual signal on my phone (screen went black and a red text said Device not connected) and the drone always returned back.

Then, in those cases, you have only lost the video feed, not connection between the remote and the drone. They are two different things.

You edited your post to include "visual connection between your phone and controller". My response was to the original statement "I lost connection". If the connection between the remote and drone are severed, no remote commands will make it to the drone.