(urgent) Mavic Air 2 lost, not located where log or "Find my drone" indicates

edouardmavic · May 10, 2021

Hello the MavicPilots community,
I know forum members usually dont like request for urgent replies
but i lost my drone in the nature and there is a rain forecast in the next 12 hours so it is kind of "now or never"...
Your help would mean a lot to me.
Thank you,
--

Here is a quick summary:
- flying around Apoyeque volcano/lake in Nicaragua
- forgot bag with batteries in the car
- took off with only 50% battery
- got to low battery level, cancelled RTH (all my fault i know) for "one more shot"
- lost signal in the worst possible moment with literally no reason (no interference, etc.) with 15+ active GPS (i dont understand...)
- could not get signal back in time
- only got it when auto-landing started 500m from my location
- tried to push it as far away from the lake cliff while auto-landing (log indicates my RC was indeed still active all this time)
- went to find it where "find my drone" indicated >> no drone
- spent 3 hours yesterday and 3 hours today with 3 other people looking for it >> drone is nowhere to be found in a 100m radius around the last registered location

last log entry:

Time	Flight Mode	GPS	Altitude	Speed	Home Distance	Battery

7m 30.5s

Auto Landing

16satellites

-59.7ft

22.0mph

1,769.3ft

5%

>> my question is:
where do you think my drone can be ?
with some underlying questions:
- any reason the last logged location may be wrong ?
- why is the last log entry at 22.0 mph and not 0.0 mph if it did indeed (auto-)land ? / could it be a crash while auto-landing?
- why is there no log entry of the last section (from 22.0mph to 0.0mph or from 22.0mph to crash) ?
- in the last logged entry, RC is still active on "UP" and "Forward". Do you think it kept being active for the last 5% and pushed the drone further away in the forward direction ?

Here is the logviewer link:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

and the log txt file is attached

I can not tell you how much it would mean if you could answer me in the next few hours as i am heading for one last 2/3 hours walk to find it tomorrow before it rains

Thank you

Phantomrain.org · May 10, 2021

edouardmavic said:
Hello the MavicPilots community,
I know forum members usually dont like request for urgent replies
but i lost my drone in the nature and there is a rain forecast in the next 12 hours so it is kind of "now or never"...
Your help would mean a lot to me.
Thank you,
--

Here is a quick summary:
- flying around Apoyeque volcano/lake in Nicaragua
- forgot bag with batteries in the car
- took off with only 50% battery
- got to low battery level, cancelled RTH (all my fault i know) for "one more shot"
- lost signal in the worst possible moment with literally no reason (no interference, etc.) with 15+ active GPS (i dont understand...)
- could not get signal back in time
- only got it when auto-landing started 500m from my location
- tried to push it as far away from the lake cliff while auto-landing (log indicates my RC was indeed still active all this time)
- went to find it where "find my drone" indicated >> no drone
- spent 3 hours yesterday and 3 hours today with 3 other people looking for it >> drone is nowhere to be found in a 100m radius around the last registered location

last log entry:

Time Flight Mode GPS Altitude Speed Home
Distance Battery

7m 30.5s Auto Landing 16satellites -59.7ft 22.0mph 1,769.3ft 5%

>> my question is:
where do you think my drone can be ?
with some underlying questions:
- any reason the last logged location may be wrong ?
- why is the last log entry at 22.0 mph and not 0.0 mph if it did indeed (auto-)land ? / could it be a crash while auto-landing?
- why is there no log entry of the last section (from 22.0mph to 0.0mph or from 22.0mph to crash) ?
- in the last logged entry, RC is still active on "UP" and "Forward". Do you think it kept being active for the last 5% and pushed the drone further away in the forward direction ?

Here is the logviewer link:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

and the log txt file is attached

I can not tell you how much it would mean if you could answer me in the next few hours as i am heading for one last 2/3 hours walk to find it tomorrow before it rains

Thank you

Couple things : Rain is not the end of the world for that drone, so just relax on that and the time line as you can extend that.

Worst case you loose the battery but the drone should be Ok .

What's more important is that you find it.

Can you post some of the video in the Cashe and I would look forward past where you were.

Phantomrain.org
Gear to fly your Mavic in the RAIN and LAND on the Water.

sar104 · May 10, 2021

The last logged location was the aircraft position when the downlink was lost. You were applying full up throttle (presumably to try to hold off autoland), and full forward elevator (to move away from the cliff). It was moving NW at 8 m/s at a height of just a couple of meters above the ground, according to the VPS data, and with the ground rising in that direction. When it lost uplink it will have stopped and completed its critical low battery autoland, so I don't see how it can have gone very far from that location. It should certainly be within 100 meters, but looks like pretty thick vegetation though. Did you continue forward stick input after you lost the video download link?

slup · May 10, 2021

Agree with @sar104 ...

"...When it lost uplink it will have stopped and completed its critical low battery autoland, so I don't see how it can have gone very far from that location."

edouardmavic said:
- lost signal in the worst possible moment with literally no reason (no interference, etc.) with 15+ active GPS (i dont understand...)

Below you have some insights into what caused the disconnect ...

Importing the flight path into Google Earth & there mark out how the topography looks relative your HP it looks like this. The green areas is within line of sight (ground level) from the HP... & there where you lost the connection, the AC was really close to ground & out of line of sight.

As you see, the area where you lost your AC isn't in LOS from where you stood ... the HP was behind a hill.

Meta4 · May 10, 2021

edouardmavic said:
- took off with only 50% battery

Your data shows you launching with only 30% in the battery !!!!
At 223.7 sec, with the battery down to 20%, you engaged Sport Mode (which burns battery wastefully, and flew back to 172 metres from home.
But then changed your mind, turned around and went out to 542 metres.
Even with the battery running down to a very low level, you kept taking it away from home and never turned back.
This drone was never going to make it home.
At 832.2 sec your battery was down to 10% and the drone started autolanding.

edouardmavic said:
- lost signal in the worst possible moment with literally no reason (no interference, etc.)

You lost signal because the drone was out of sight behind a ridge that blocked signal.

edouardmavic said:
with 15+ active GPS (i dont understand...)

Your drone had a clear, unobstructed line of sight to the satellites 20000 km above the earth.
GPS has nothing to do with the control signal between the drone and controller.

edouardmavic said:
- why is the last log entry at 22.0 mph and not 0.0 mph if it did indeed (auto-)land ? / could it be a crash while auto-landing?

Because you were fighting against the autolanding and had the right stick pushed full forward/right

edouardmavic said:
- why is there no log entry of the last section (from 22.0mph to 0.0mph or from 22.0mph to crash) ?

Because the signal was blocked .. no signal = no data.

It really looks like you did everything you could to ensure that the drone wouldn't be able to return.

edouardmavic · May 10, 2021

hello all, thank you so much for your answers.
sar104, i do not remember if i did continue forward stick input after i lost the video download link.
Would that change the drone itinerary before crashing ?
or the RC input would not reach/move the drone when the downlink is lost ?

sar104 said:
The last logged location was the aircraft position when the downlink was lost. You were applying full up throttle (presumably to try to hold off autoland), and full forward elevator (to move away from the cliff). It was moving NW at 8 m/s at a height of just a couple of meters above the ground, according to the VPS data, and with the ground rising in that direction. When it lost uplink it will have stopped and completed its critical low battery autoland, so I don't see how it can have gone very far from that location. It should certainly be within 100 meters, but looks like pretty thick vegetation though. Did you continue forward stick input after you lost the video download link?

View attachment 128917

sar104 · May 10, 2021

edouardmavic said:
hello all, thank you so much for your answers.
sar104, i do not remember if i did continue forward stick input after i lost the video download link.
Would that change the drone itinerary before crashing ?
or the RC input would not reach/move the drone when the downlink is lost ?

I don’t recall ever seeing a documented case of uplink maintained after downlink was lost, so whether it can happen is speculation on my part. In general I would guess not. But, if it did continue to respond to RC control inputs, and if you don’t recall what those inputs might have been, or for how long they continued, then it had a few percent of battery left to travel in an unknown direction - if it didn’t hit vegetation or terrain.

Capt KO · May 10, 2021

Ouch. Ph # on drone? 1st thing I do on all my drones. GL

tlswift58 · May 10, 2021

Meta4 said:
Your data shows you launching with only 30% in the battery !!!!
At 223.7 sec, with the battery down to 20%, you engaged Sport Mode (which burns battery wastefully, and flew back to 172 metres from home.
But then changed your mind, turned around and went out to 542 metres.
Even with the battery running down to a very low level, you kept taking it away from home and never turned back.
This drone was never going to make it home.
At 832.2 sec your battery was down to 10% and the drone started autolanding.

You lost signal because the drone was out of sight behind a ridge that blocked signal.

Your drone had a clear, unobstructed line of sight to the satellites 20000 km above the earth.
GPS has nothing to do with the control signal between the drone and controller.

Because you were fighting against the autolanding and had the right stick pushed full forward/right

Because the signal was blocked .. no signal = no data.

It really looks like you did everything you could to ensure that the drone wouldn't be able to return.

Don't get WHY anyone would fly even at 50% battery at take-off, much less it actually being 30%. Then flying way out (500+ meters) on a low battery and expect it to come home.

Pilot seems to be very new and had no idea what they were doing to make sure an ill-fated flight.

edouardmavic · May 10, 2021

sar104 said:
I don’t recall ever seeing a documented case of uplink maintained after downlink was lost, so whether it can happen is speculation on my part. In general I would guess not. But, if it did continue to respond to RC control inputs, and if you don’t recall what those inputs might have been, or for how long they continued, then it had a few percent of battery left to travel in an unknown direction - if it didn’t hit vegetation or terrain.

thank you sar104 for your relevant and quick answers