Please help me analyze the flight log to recover a drone

[essenciya]

Dear people,
An unfortunate situation happened today to my drone while flying it I lost a signal and drone activated return home mode, at some point, it regained the signal and immediately after tried to land and landed in trees, it was still about 60% charged and was still sending video feed to the controller, but it was tilted up so footage was not useful. Gimble was not responding to the controller and drone was not able to get back to fly, so I had screenshots of what DJI GO4 app was showing, also GPS coordinates from the flight record in the app. The one thing I was able to do is to activate gimble calibration which moved the gimble and I've got to see a bit more useful image from the drone, but then gimble stuck for and also app in fly mode was showing constantly 10% gimble calibration overlay so at the end it didn't help much. We did scout the area where last GPS coordinates were recorded, and couldn't find a drone. Now we are back at the computer analyzing the data from drone what is strange is that crash coordinates are very close to the home position and we were physically close to it and couldn't hear the drone (to be clear around was loud too, but still). Would anybody please with experience be able to look at the log data and tell what is the most probable location (lon, lat) we should look for it?

 

[Mossiback]

Did you try using the Find my Drone feature of Go 4?

 

[Simmo]

Hey Bud, sorry for your loss.
Home point looks like it was recorded a little distance away (a matter of feet) as you didn't have good GPS coverage.
That being said, it looks like it came back pretty close (within 12ft?)
It should be in the trees right near where you were??

 

[essenciya]

Hey Bud, sorry for your loss.
Home point looks like it was recorded a little distance away (a matter of feet) as you didn't have good GPS coverage.
That being said, it looks like it came back pretty close (within 12ft?)
It should be in the trees right near where you were??View attachment 66506

That's what i thought first. Looked today, not there. Last altitude is 108 meters. Now I am thinking it might be up ON the cliff, in the trees.

 

[essenciya]

Did you try using the Find my Drone feature of Go 4?

I wish! First the app glitched and had no access to the hoke menu, then it died.

 

[essenciya]

@msinger I heard about your legendary log analytics. Would you mind terribly to have a look at my log, please? Just need another opinion if the drone could indeed have landed 108m above home. And we need to climb multipitch tomorrow. Last message was: motor obstructed... It feels like it could have stuck in those trees on the rock face, but I lack experience to make a conclusion here. Thanks a lot!

 

[Simmo]

@sar104

 

[Meta4]

That's what i thought first. Looked today, not there. Last altitude is 108 meters. Now I am thinking it might be up ON the cliff, in the trees.

It appears that you were flying from the side of a cliff that blocked GPS.
You had no GPS and couldn't record a home point until 2:01.1, but you had been flying some distance in those two minutes and we can't tell how far that was from the recorded home point.

At about 6:43.3 while autolanding, your drone crashed in trees (?) 109 metres directly above the recorded homepoint - but that is not where you launched from..
You had been adding throttle and rudder input from 6:36.2 soon after the drone commenced the descent after RTH to above the recorded home point.
At 6:43.3 the drone rolled nearly upside down and pitched heavily and it stopped descending.
The recorded data continues for another four seconds with the drone hanging there.

We know the drone ended up directly above the recorded homepoint (which is not the launch point).
We can't tell how far that is from where you launched but we do have a good GPS location for it.
We also know that the recorded home point was only a little higher than the launch point.

The drone is at 8.00868N 98.83580E and about 109 metres higher than where you launched from.

You chose a very bad spot to launch and by going up close to the cliff, you made another mistake.
Descending in autoland beside a tree covered cliff which would block GPS was extremely unwise.
The only safe way to bring the drone back would have been to have cancelled RTH and resumed control, flown the drone a couple of hundred feet out from the clif and brought it down where it had good GPS and then brought it towards you once it was down near your level.

 

[sar104]

Dear people,
An unfortunate situation happened today to my drone while flying it I lost a signal and drone activated return home mode, at some point, it regained the signal and immediately after tried to land and landed in trees, it was still about 60% charged and was still sending video feed to the controller, but it was tilted up so footage was not useful. Gimble was not responding to the controller and drone was not able to get back to fly, so I had screenshots of what DJI GO4 app was showing, also GPS coordinates from the flight record in the app. The one thing I was able to do is to activate gimble calibration which moved the gimble and I've got to see a bit more useful image from the drone, but then gimble stuck for and also app in fly mode was showing constantly 10% gimble calibration overlay so at the end it didn't help much. We did scout the area where last GPS coordinates were recorded, and couldn't find a drone. Now we are back at the computer analyzing the data from drone what is strange is that crash coordinates are very close to the home position and we were physically close to it and couldn't hear the drone (to be clear around was loud too, but still). Would anybody please with experience be able to look at the log data and tell what is the most probable location (lon, lat) we should look for it?

That's a very strange flight record. The aircraft behaved basically as described, at least until the end of the flight. Note that the home point was not recorded until 122 seconds into the flight by which time the aircraft had moved 11 m to the NW, so that needs to be taken into account. The unusual data are at the end. If we look at altitude, pitch and roll:



The aircraft switches to autolanding at 394 s and an altitude of 130 m. It starts to descend at 3 m/s but at 403 s, having only descended 20 m to 109 m, the VPS height goes to zero, the aircraft stops descending, the pitch goes to 66° and the roll goes to -144°. It now appears to be stationary, nearly upside down, 109 m (360 ft) above the home point, with motor obstructed messages. I assume that the trees there are not 100 m tall? Then the log stops.

The highest terrain nearby appears to be only 20 or 30 m higher than the launch point, so that doesn't help. How tall are the trees in that location?

 

[Gorm]

Could it be a bird strike that caused the motor obstruction?

 

[sar104]

Could it be a bird strike that caused the motor obstruction?

It could, but unless the bird then grabbed the aircraft that doesn't explain the subsequent lack of descent.

 

[essenciya]

It appears that you were flying from the side of a cliff that blocked GPS.
You had no GPS and couldn't record a home point until 2:01.1, but you had been flying some distance in those two minutes and we can't tell how far that was from the recorded home point.

At about 6:43.3 while autolanding, your drone crashed in trees (?) 109 metres directly above the recorded homepoint - but that is not where you launched from..
You had been adding throttle and rudder input from 6:36.2 soon after the drone commenced the descent after RTH to above the recorded home point.
At 6:43.3 the drone rolled nearly upside down and pitched heavily and it stopped descending.
The recorded data continues for another four seconds with the drone hanging there.

We know the drone ended up directly above the recorded homepoint (which is not the launch point).
We can't tell how far that is from where you launched but we do have a good GPS location for it.
We also know that the recorded home point was only a little higher than the launch point.

The drone is at 8.00868N 98.83580E and about 109 metres higher than where you launched from.

You chose a very bad spot to launch and by going up close to the cliff, you made another mistake.
Descending in autoland beside a tree covered cliff which would block GPS was extremely unwise.
The only safe way to bring the drone back would have been to have cancelled RTH and resumed control, flown the drone a couple of hundred feet out from the clif and brought it down where it had good GPS and then brought it towards you once it was down near your level.

Thank you Meta4 for your analysis. I understand now that was very... bad launching spot and the whole crash was the pilot's mistake. The cliff right behind the launching area is blocking the GPS greatly and I learned this lesson the hard way. I also think I should have canceled the RTH but at the moment the connection with the controller was so weak I only had few seconds of control before it was too late. Special thank you for the coordinates you think the drone is at. I'll make another effort to recover it tomorrow.

 

[essenciya]

That's a very strange flight record. The aircraft behaved basically as described, at least until the end of the flight. Note that the home point was not recorded until 122 seconds into the flight by which time the aircraft had moved 11 m to the NW, so that needs to be taken into account. The unusual data are at the end. If we look at altitude, pitch and roll:

View attachment 66552

The aircraft switches to autolanding at 394 s and an altitude of 130 m. It starts to descend at 3 m/s but at 403 s, having only descended 20 m to 109 m, the VPS height goes to zero, the aircraft stops descending, the pitch goes to 66° and the roll goes to -144°. It now appears to be stationary, nearly upside down, 109 m (360 ft) above the home point, with motor obstructed messages. I assume that the trees there are not 100 m tall? Then the log stops.

The highest terrain nearby appears to be only 20 or 30 m higher than the launch point, so that doesn't help. How tall are the trees in that location?

Thank you sar104 for looking into my log. I questioned myself the same about 109m high trees, but after scouting the area today, I came to a conclusion that it's not on just a tree, but there is an overhanging cliff right behind with few trees and bushes on a side of it, so most likely the drone is stuck in there. The cliff is very high (one of the rock climbing route right behind the HP is 130m and it doesn't go all the way up)

 

[sar104]

Thank you sar104 for looking into my log. I questioned myself the same about 109m high trees, but after scouting the area today, I came to a conclusion that it's not on just a tree, but there is an overhanging cliff right behind with few trees and bushes on a side of it, so most likely the drone is stuck in there. The cliff is very high (one of the rock climbing route right behind the HP is 130m and it doesn't go all the way up)

Then that's clearly a likely explanation. The Google Earth DEM doesn't show any terrain even remotely that high, so it must be wrong - that does happen sometimes in locations with cliffs.

 

[JDFMavic]

I'm much too new to the sport to give you any advice on how to locate your drone. The reason I joined this forum was to learn from the pilots that make these kinds of mistakes and the pros who help them recover from them. There's many years of experience here and many generous member who willingly share their knowledge.

The only advice I can offer is to be very careful trying to retrieve your bird from the side of a cliff. Unlike you, your drone can be replaced.

 

[Shon]

I’m new to the Air, but not to drones. I sweat bullets flying into a narrow canyon. Saturday I saw a small waterfall I wanted to film. Narrow canyon, lots of rocks and trees, some power lines over the canyon, minimal VLOS partially obscured by trees and bushes... flight would be over river rapids, and likely the drone would not be retrievable in this terrain if crashed. I decided not to risk it. There will be other waterfalls... and better subjects to film. Even if I managed to get the shot I was looking for, I doubt it would have been all that “epic” anyway...

 

[slkfis]

This is a great example of the cooperation and knowledge of the folks on this Forum. Thanks from me to all the people who worked on this diagnosis. A lesson learned, always check the available satellites before flying!

But I have one question, Did he find his Drone? He has left us with a "Cliff Hanger"

lol
slkfis

 

[Peio64270]

(...) after scouting the area today, I came to a conclusion that it's not on just a tree, but there is an overhanging cliff right behind with few trees and bushes on a side of it, so most likely the drone is stuck in there. The cliff is very high (one of the rock climbing route right behind the HP is 130m and it doesn't go all the way up)

Is it this cliff ? If so, it doesn't appear at all in Google Earth. But I already observed such discrepancies between real elevations and Google data in my area. Some are off by more than 100m.
Anyway, take care if you decide to explore this rock and don't go there alone.

 

[IgorD2]

omg

 

[essenciya]

Hi there, sorry for not finishing on this story I'm going to fix it now.
Peio64270 - yes this is the real rock, Google maps/earth does not represent the hight of the area correctly.
I had to stay longer in the area and explore more. I've returned there and found nothing on the coordinates, then I realized the drone should be way above on the same coordinates, and even though I climb, this mountain was a bit over my skill, so I hired local rock climbers to do the job, I had a deal with them I'll pay them X and if they find a drone I double that. I gave them coordinates and photos of what drone saw the last (it regained connection with the controller after the crash and still was able to pass video feed). But they also did not find anything, they also scouted the mountain at the bottom.
By now I left the area posting on FB page of local climbers a message with the reward offer.
A few days ago one of the climbers contacted me posting the picture of the drone looked like mine, claiming that he found it and asking for reward, I asked for the serial number picture and unfortunately, it didn't match. So I think I'm not the only one who lost it there, climbers told me they get hired for this kind of rescue missions a lot in the area.
So yes, the takeaway lesson here, always fly your drone with strong gps signal, always withing the sight, always have enough memory on the phone to cache the footage, also I'm thinking of buying a Marco Polo locator (radar?).
Safe flights!