Lost drone: possible crash due to lost signal?

[fharrihill]

Hi everyone

I fly a DJI Mavic air 2 for work, and I don't know much about it apart from using pre-set flight paths and taking panoramic photos from set waypoints.
I was flying today using Litchi on a Samsung Galaxy tablet when I suddenly lost signal. I wasn’t flying far or in a range-challenging situation, so I don’t believe this was a simple out-of-range issue. I was unable to reconnect, and the drone never returned. The area where the drone launched is a dry floodplain that's quite open with only small shrubs scattered around, but where the drone was flying towards (about 200m from the home point) there are several large trees and thick shrubs. At the point where the drone had lost connection it was out of my eyesight and I couldn't hear it flying.

I’ve since:

• Retrieved the flight log from Litchi
• Uploaded it to PhantomHelp and reviewed the map
• Thoroughly searched the area around the last recorded connection point (as well as we could between the shrubs)

Unfortunately, no luck so far.

At this point, I’m trying to understand:

• How far beyond the last recorded point the drone may realistically have traveled
• Whether there are common failure modes (battery, GPS, failsafe behavior, etc.) that could explain continued flight or drift after signal loss
• Any additional recovery strategies I might not be thinking of

Also, I'm not sure if this is connected to my issue but before the flight began I had an error message on the Litchi screen ("Failed in initializing flight simulator. Try again") which was preventing me from launching the drone, so I restarted the app and the error was gone

If anyone is willing to take a look or offer general guidance, I’d really appreciate it. At this point I'm guessing even if I find the drone it will be broken, so we are looking into a replacement.

Thanks in advance for any help or insight.

 

[Meta4]

I was flying today using Litchi on a Samsung Galaxy tablet when I suddenly lost signal.

Drones don't crash due to losing signal.
But crashing or losing power would show on the screen as losing signal.
If your drone was well above the vegetation, it probably didn't crash.

I’ve since:

• Retrieved the flight log from Litchi
• Uploaded it to PhantomHelp and reviewed the map

Please post a link for the Phantomhelp report

At this point, I’m trying to understand:

• How far beyond the last recorded point the drone may realistically have traveled
• Whether there are common failure modes (battery, GPS, failsafe behavior, etc.) that could explain continued flight or drift after signal loss

On losing signal your drone would continue the Litchi waypoint mission if you have that option selected in settings.
If not It should return to home.
That it didn't return suggests that stopped flying somewhere along the route.

 

[fharrihill]

Drones don't crash due to losing signal.
But crashing or losing power would show on the screen as losing signal.
If your drone was well above the vegetation, it probably didn't crash.

Please post a link for the Phantomhelp report

On losing signal your drone would continue the Litchi waypoint mission if you have that option selected in settings.
If not It should return to home.
That it didn't return suggests that stopped flying somewhere along the route.

Thanks for your quick reply!
Here is the Phantomhelp report DJI Flight Log Viewer - PhantomHelp.com
I did look for the drone at the end point of the waypoint mission. Unfortunately a lot of the route isn't accessible to search because of dense vegetation. The settings are set to 'hover' if connection is lost. Please let me know if there are other possibilities to where it may have landed! Thanks

 

[Meta4]

Thanks for your quick reply!
Here is the Phantomhelp report DJI Flight Log Viewer - PhantomHelp.com
I did look for the drone at the end point of the waypoint mission.

The flight data ends with no changes in the pitch, roll and yaw data, so we know that there was no crash at that point and the drone probably didn't end up in that tree..
But just to eliminate that as a factor, the obvious point to address is the height of the large tree/s where the data ends.
The drone was flying at a height of 33.5 metres relative to the home point.
The ground level around the tree was 5 metres higher than the homepoint.
Would that tree be 28.5 metres high or somewhere close to that height?

The most likely scenario would be that there was a sudden loss of power, maybe due to a battery dislodging.
If that happened, the drone would not fall straight downwards, but continue forwards as it fell.
With the drone flying at 9.8 metres/sec, it would take approximately 2.5 seconds to fall to the ground, and travel approximately 20-25 metres beyond the last recorded location.

That would put a fallen drone close to the southwestern edge of the tree canopy and any searching should be around there at -34.13052° 140.74096°.

The drone could have been caught in the tree branches on the way down, so also look up when searching.

 

[PHZ]

Great analysis Meta4, as always!

 

[AMann]

Very good of you to help, Meta4. Hope fharrihill recovers it and writes back about the results.

Note to self: in Litchi, set the on signal loss to RTH, not hover…

 

[PINEBARON]

Note to self: in Litchi, set the on signal loss to RTH, not hover…

Thats a good point to note for sure!

 

[fharrihill]

Hi everyone and thanks for the help @Meta4 !!
This morning I searched the area around -34.13052° 140.74096° and I found the drone! You were correct that the battery had fallen out, and thankfully the reeds seemed to have cushioned the fall as it seems to be in working order. I wasn't able to find the battery in the nearby area, but I have two backups so I am not too worries about that.
Thanks again for your advice, I will now always double check the battery is connected securely!

PS for your interest I have attached a photo of where the drone was found, to show how hidden it was next to a pile of rubbish!

 

[MS Coast]

This morning I searched the area around -34.13052° 140.74096° and I found the drone! You were correct that the battery had fallen out, ... I will now always double check the battery is connected securely!

Well, there's a happy ending and a sterling example of the value of the rigorous analysis of flight logs over speculation and conjecture. Nice job, @Meta4.

A battery disconnect can be the result of battery swelling. It's a good idea to inspect the battery before and immediately after a flight for any signs of swelling. It would also be a good idea to give the drone a very close examination to look for any cracks that might have closed, propeller damage (including the hubs) and problems. A cautious and conservative test flight before venturing too far is a good idea, too.

 

[AMann]

I don’t have the link, but you can also get straps to hold the battery down better. They’re not too expensive and definitely worth the effort!