Lost DJI Mavic Pro during Litchi mission

[Akemi]

I sent my Mavic Pro on a long 5.9 mile mission at an altitude of 100 feet(excluding a few where I told it to go 200 feet) with blowing SE at 9mph with 82% battery life left. The battery meter showed 16 minutes and 21 seconds left with a RED area covering just over half the bar. The speed I told it to travel was 33.6mph for the full trip. The first 2 miles was spent in the direction or general direction of the SE winds(headwind). The rest of the trip, it was moving away from or in the direction the winds were blowing. I attached a Link(Mission Hub - Litchi) from Litchi showing the flight path it should've followed. I am hoping someone can figure out based off the info and data I provided, where low battery RTH might've kicked in, where it might've landed and where it might be if RTH didn't kick in and it kept going until it decided to land. This drone is my life, I really need help figuring this thing out. Norfolk Southern Police(their train tracks was where my drone should've spent it's time at) and the Chesapeake PD(in case it's found) are already looking into it. There was nothing at or above 100 feet that it could've hit unless it decided that it found a nearby radio/TV antenna attractive enough to ram into.

 

[Simmo]

Post your flight logs off your phone or tablet too.
Follow these instructions and post a link back here.
DJI Flight Log Viewer | Phantom Help

 

[Akemi]

Here is the flight log. Along with a screenshot of the last telemetry I got before it left to do it's thing.



DJI Flight Log Viewer - PhantomHelp.com

 

[Meta4]

Here is the flight log. Along with a screenshot of the last telemetry I got before it left to do it's thing.

There's not enough information to help you on this one.
All we can tell is that you launched with a good battery and flew off.
I can see that the terrain in terrain in the vicinity is pretty flat so rising terrain probably wasn't an issue and it looks like there aren't a lot of tall obstacles.
Can you provide your flight plan to show where you were flying to, altitudes, speeds etc?
Did you have obstacle avoidance enabled?

 

[Akemi]

There's not enough information to help you on this one.
All we can tell is that you launched with a good battery and flew off.
I can see that the terrain in terrain in the vicinity is pretty flat so rising terrain probably wasn't an issue and it looks like there aren't a lot of tall obstacles.
Can you provide your flight plan to show where you were flying to, altitudes, speeds etc?
Did you have obstacle avoidance enabled?

The path it would've taken is here: Mission Hub - Litchi - Everything is there, and the winds were blowing southeast at 8mph at 200 feet altitude.

I think I disabled OA on the DJI Go, but I do not know if Litchi has its own setting for it or what it is at by default. The only tower in the area that I saw(after the fact) was a cell tower but the drone would've passed it by 300 feet. I am confident someone could figure out the possible landing site(assuming both it tried to RTH and that it continue to fly until it fell from the sky/landed - whichever Litchi does by default). I saw a few people up here who lost theirs and users figured out the possible landing site based off weather data, speed, altitude change, and battery life. I'm just not patient or smart enough to figure it out and I have tried for 24 hours without sleep.

By the way, the max distance between the take off point and the furthest path is about 2.7 miles. I do not know why it didn't return. Either recording during the entire trip drained the battery faster, it hit something(nothing is at or above 200 feet in the area, I think), or it went haywire because the cell tower confused the drone.

 

[Meta4]

I am confident someone could figure out the possible landing site(assuming both it tried to RTH and that it continue to fly until it fell from the sky/landed - whichever Litchi does by default).
I saw a few people up here who lost theirs and users figured out the possible landing site based off weather data, speed, altitude change, and battery life.
I do not know why it didn't return. Either recording during the entire trip drained the battery faster, it hit something(nothing is at or above 200 feet in the area, I think), or it went haywire because the cell tower confused the drone.

I'm not so confident with this incident because there is very little to work with.
You were down low which probably explains losing signal.
A few common causes of problems can be eliminated, but there's no obvious potential cause.
Your flight plan shows there was only about 30 ft variation in elevations across the route.
There's no obvious point where you've set the altitude too low.
The distance shouldn't have been a problem.
If the winds were 8mph, that shouldn't have been an issue either.

That leaves two possibilities unaccounted for.
1. Was there a tree, mast etc on your path that was high enough where your Mavic was only 30 metres up?
Particularly somewhere that the ground level may have been higher than the launch point?
2. Did your drone suffer a mystery sudden loss of power?

 

[Akemi]

I'm not so confident with this incident because there is very little to work with.
You were down low which probably explains losing signal.
A few common causes of problems can be eliminated, but there's no obvious potential cause.
Your flight plan shows there was only about 30 ft variation in elevations across the route.
There's no obvious point where you've set the altitude too low.
The distance shouldn't have been a problem.
If the winds were 8mph, that shouldn't have been an issue either.

That leaves two possibilities unaccounted for.
1. Was there a tree, mast etc on your path that was high enough where your Mavic was only 30 metres up?
Particularly somewhere that the ground level may have been higher than the launch point?
2. Did your drone suffer a mystery sudden loss of power?

Looking at the FCC's database, there was only one cell tower within the flight path that was in my drones altitude but it was NOT on the drone's flight path. And I do not think there is a single tree in the entire Southeast Virginia(where I am) area that is 100 feet or taller. Unless it decided to do a RTH and bad luck sent it right into that skinny cell tower, I do not think it would've hit it.

A power loss? I just got the drone from DJI a week before it decided to go Flight 370.

 

[Meta4]

I do not think there is a single tree in the entire Southeast Virginia(where I am) area that is 100 feet or taller.
Unless it decided to do a RTH and bad luck sent it right into that skinny cell tower, I do not think it would've hit it.

A Litchi waypoint mission will continue to the end and won't initiate RTH.
Because there's nothing to pinpoint any particular problem or potential cause of an incident, I was going over anything the might cause a problem for your flight.
If your drone was at 30 metres passing over land that was 30 ft higher than launch point and there was a 70 ft tree or mast on that land, that would be a problem for the drone.

A power loss? I just got the drone from DJI a week before it decided to go Flight 370.

There's nothing to indicate a power loss (there's not much to indicate anything) but given the lack of other potential causes, that's a possibility that should be considered.

 

[sar104]

Here is the flight log. Along with a screenshot of the last telemetry I got before it left to do it's thing.



DJI Flight Log Viewer - PhantomHelp.com

View attachment 59041

I think you possibly didn't allow enough ground clearance between waypoints 11 and 12:



For some reason you dropped the altitude down to around 30 meters, and the ground there is a bit higher. Taking into account altitude uncertainties it may not have been enough.

 

[Akemi]

A Litchi waypoint mission will continue to the end and won't initiate RTH.
Because there's nothing to pinpoint any particular problem or potential cause of an incident, I was going over anything the might cause a problem for your flight.
If your drone was at 30 metres passing over land that was 30 ft higher than launch point and there was a 70 ft tree or mast on that land, that would be a problem for the drone.

There's nothing to indicate a power loss (there's not much to indicate anything) but given the lack of other potential causes, that's a possibility that should be considered.

I have been seeing conflicting statements about battery RTH using Litchi. Some saying it will, some saying it won't. That just make it even harder to figure out. 100 feet was the lowest altitude I told it to go and it would've only happened over railroad tracks.

I think you possibly didn't allow enough ground clearance between waypoints 11 and 12:


For some reason you dropped the altitude down to around 30 meters, and the ground there is a bit higher. Taking into account altitude uncertainties it may not have been enough.

It would've flown over railroad tracks there. The trees that hover those tracks are no higher than 50 feet....maybe. I will go over and check anyway, and ask Norfolk Southern's PD to check if I think I might get arrested for going on their tracks.

 

[Meta4]

I have been seeing conflicting statements about battery RTH using Litchi. Some saying it will, some saying it won't. That just make it even harder to figure out. 100 feet was the lowest altitude I told it to go and it would've only happened over railroad tracks.
It would've flown over railroad tracks there. The trees that hover those tracks are no higher than 50 feet....maybe.

That curved corner to the south of waypoint 12 goes very close to trees.
That looks like a good spot to look.

 

[sar104]

I have been seeing conflicting statements about battery RTH using Litchi. Some saying it will, some saying it won't. That just make it even harder to figure out. 100 feet was the lowest altitude I told it to go and it would've only happened over railroad tracks.

There should be no confusion over RTH during a mission. It will abort and RTH if the "SMART_BATTERY_battery" level falls below the "SMART_BATTERY_goHomeBattery" level.

 

[Akemi]

That curved corner to the south of waypoint 12 goes very close to trees.
That looks like a good spot to look.

I will check back here if I find it. It would be great if I found it, broken or not, so I can use my Refresh warranty to replace it.

There should be no confusion over RTH during a mission. It will abort and RTH if the "SMART_BATTERY_battery" level falls below the "SMART_BATTERY_goHomeBattery" level.

Is there any way of knowing what that level was? The screenshot I shared showed it was just over half of the 16 minute bar, but I see no data.

 

[Meta4]

Is there any way of knowing what that level was? The screenshot I shared showed it was just over half of the 16 minute bar, but I see no data.

RTH isn't going to be an issue past waypoint 12.
There are no high points where you were flying at 30 metres after that.
If you were going to fly into trees. south of waypoint 12 is the most likely point for that to happen.

 

[Akemi]

Just an update. Norfolk southern Police said that day my drone went missing, one of their engineers spotted it flying low, maybe 25 feet. It was low enough where he had to stop the train. He also said they last saw it going to waypoint and 12. The officer said he'd look for it between waypoint 12 and 13 as much as he can.

If they cannot find it or refuse to look much due to the amount of work required, I'll have to ask a drone pilot to scan for it.

 

[MountainMan2017]

Sorry for your loss, hope you find it . I lost my Team Black Sheep Drone built with. DJI Naza V2 with GPS years ago way before these newer models came out. My loss cost me $1,500 including a brand new Go Pro hero 3+ silver. 4 days old all of it. I was sick for days and it still hurts. I definitely lost mine but I hope you find yours . Best of luck keep us posted

 

[Akemi]

Sorry for your loss, hope you find it . I lost my Team Black Sheep Drone built with. DJI Naza V2 with GPS years ago way before these newer models came out. My loss cost me $1,500 including a brand new Go Pro hero 3+ silver. 4 days old all of it. I was sick for days and it still hurts. I definitely lost mine but I hope you find yours . Best of luck keep us posted

That sounds horrible. This drone is my SECOND DJI Mavic Pro since December 2018. Neither one lasted longer than a week. I'm likely going to have to buy ANOTHER one unless someone finds it and doesn't keep it. I'm putting flyers up just in case.

 

[Meta4]

That sounds horrible. This drone is my SECOND DJI Mavic Pro since December 2018. Neither one lasted longer than a week.

Maybe there's a lesson in that?

 

[Akemi]

It's raining here and everything wet will be iced over tomorrow so I've concluded the search and rescue mission. It's presumed lost. So I'll just buy a Mavic Pro 2 with my tax return next month and slap a GPS tracker on it.

Maybe there's a lesson in that?

Yep, listen to the advice of Drone YouTubers.

 

[Roamer105]

Sorry to hear about your loss. I had my own story recently and I know how this feels.

Just looked at your mission. You lost connection rather soon just before WP2 where your elevation is set to 102' (you used ground level offset). WP2 is also where you meet the railroad tracks (Portlock Road). I am looking at a power transmission line following that road across the tracks and the line is pushed rather high (probably to allow for clearance to the rail activity). I don't know if it managed to clear the lines: 100' +/- possible altimeter error which can be significant depending on weather/temperature conditions (GPS altitude information is not very accurate at all so the Mavic relies on the barometric altimeter). I would definitively take a look in that area.

Rules from someone that got burnt by WP missions as well:
1) Don't mix ground level settings with relative to takeoff settings.
2) Make sure to TURN OFF "smart RTH"
3) NEVER design a mission that pushes the maximum flight time (such as yours). Note you had some critical cell deviations - may have been low battery temperature in the beginning.
4) Check, double-check and tripple-check your mission plan before attempting the flight. I any doubt - don't fly it.