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Lost my Mavic Pro! GPS Signal?? HELP

C.h.gogo

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Hi everybody,
I went for a flight with my DJI Mavic Pro today. The wind was so strong that it blew my drone away, we were following it with the car until it run out of battery and tried to land, in exactly this moment (video) signal turned off. It landed in the middle of a sugar cane field..

Since I was just 200 m far away I ran to the location it was supposed to be and the I got connected to the drone, saw the live view and everything, but than it turned off and I couldn’t find it in 6 hours searching :/

Now I have some questions for keep on searching tomorrow... I have the track of the whole flight, very precise I think (17 satelites when tracking was finished). The last cordinates of the flight record are more or less 20 meters away from the cordinates shown on “find my drone” (20 meters in (last) flight direction (against the wind))

1. Does the drone loose (satelite) signal when its on the ground? (Reason for wrong coordinates on”find my drone”?)
2. At what moment does DJI stop the flight record? At the moment it turns of the motor? So it got in contact with the sugar cane and immediatly turned of the motor and stoped recording?

Many thanks for any tips!!!
 

JDawg

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"I went for a flight with my DJI Mavic Pro today. The wind was so strong that it blew my drone away, " Umm... never mind... Post your logs and there are a couple of people here who can most likely lead you right to it.
 
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C.h.gogo

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"I went for a flight with my DJI Mavic Pro today. The wind was so strong that it blew my drone away, " Umm... never mind... Post your logs and there a are couple of people here who can most likely lead you right to it.
Thanks! Already posted the FlightRecord.txt
 

sar104

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You weren't kidding about the wind. How did you imagine that would not end badly?


Anyway - the log doesn't quite go to landing, but close enough to make a pretty good estimate. Comparison of the flight track with the ultrasonic height measurements indicates that the track is within a few meters of reality.

That puts the landing as shown below. The imagery is quite recent - March this year - so you may be able to count crop rows to get an accurate location.

1542260043256.jpeg
 

xman1

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Get a tracker for your drone when you do find it. The most long range lightweight tracker that I know of that is not cellular based (cell based won't work when there is no cell signal but this device will) is as follows:

Loc8tor Lite - Loc8tor

This model will go to 400 feet. When my drone went down in dense woods due to a malfunction that caused it to not hover, I would have never found it without this device. It is tiny, has no weight, and I attached it to the front of the Mavic. Works great!

 

Simmo

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@sar104 in your pic, what height does the yellow line stop at? Could there have been crops at that height, and the drone stopped around there?
 

gtione

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Get a tracker for your drone when you do find it. The most long range lightweight tracker that I know of that is not cellular based (cell based won't work when there is no cell signal but this device will) is as follows:

Loc8tor Lite - Loc8tor

This model will go to 400 feet. When my drone went down in dense woods due to a malfunction that caused it to not hover, I would have never found it without this device. It is tiny, has no weight, and I attached it to the front of the Mavic. Works great!

Yes this is a very good idea. Got mine ages ago but thankfully not had a need to use it.

10782064384_IMG_0180.JPG
 

Meta4

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@sar104 in your pic, what height does the yellow line stop at? Could there have been crops at that height, and the drone stopped around there?
.The final data point shows VPS reading 13 feet above something.
The Mavic was in autoland and going down but it was 6 kilometres from launch point and losing signal.
The data stopped before touchdown.
The flyer was pushing the right stick forward which is going to make for a crash rather than a landing.

The last cordinates of the flight record are more or less 20 meters away from the cordinates shown on “find my drone” (20 meters in (last) flight direction (against the wind))

1. Does the drone loose (satelite) signal when its on the ground? (Reason for wrong coordinates on”find my drone”?)
2. At what moment does DJI stop the flight record? At the moment it turns of the motor?
Find-my-drone can only show you the last recorded position for the drone.
If it was moving when signal was lost, the drone won't be at that point.
1. If the drone ends up updide down or under something, it may lose GPS reception.
2. The flight record stops when signal is lost or when the Mavic is powered off.
 
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C.h.gogo

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Many thanks for all the hints! I am on my wsy to the field again.

One rhing I haven’t mentioned clearly before... just before it landed/crashed, Video signal was disconnected, I ran into the field and got connected again and could even see the live image again (couldn’t recognize anything, just dry grass)
1. “Find my drone” shows me 14.3821330,-90.8276750 (got signal when already landed)
2. Last flight record shows me 14.3819890,-90.8277210

@sar104 your location is almost in the center of these to pooints... how accurate eould you say is you location? more or less a radius of...? Will update you as soon as I found something.
 

sar104

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Many thanks for all the hints! I am on my wsy to the field again.

One rhing I haven’t mentioned clearly before... just before it landed/crashed, Video signal was disconnected, I ran into the field and got connected again and could even see the live image again (couldn’t recognize anything, just dry grass)
1. “Find my drone” shows me 14.3821330,-90.8276750 (got signal when already landed)
2. Last flight record shows me 14.3819890,-90.8277210

@sar104 your location is almost in the center of these to pooints... how accurate eould you say is you location? more or less a radius of...? Will update you as soon as I found something.
My estimate was an extrapolation to ground level, and suggested that it travelled around 9 meters beyond the last flight record point. Your "Find my drone" point suggests that it traveled a further 8 or 9 meters on the same heading, which is perfectly consistent with just a small error in altitude - i.e. it was a bit higher off the ground than` the data indicated. I had omitted to plot that point previously but, given where it is, I'd look there first. I'd be extremely surprised if it was more than a few meters away.
 

sar104

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@sar104 in your pic, what height does the yellow line stop at? Could there have been crops at that height, and the drone stopped around there?
The flight data, relative to the Google Earth DEM, indicates 11 meters. The VPS, which had been intermittently indicating credible altitudes since the 900 second mark, has data at the last recorded flight point after a link loss of 2.2 seconds, of 4 meters. Over a surface like crops that may be somewhat inaccurate but does mean that it got returns off something and was reasonably close to the ground. I'd call those two data sets likely consistent.

Graph0.png
 

Mike Smith

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Hi everybody,
I went for a flight with my DJI Mavic Pro today. The wind was so strong that it blew my drone away, we were following it with the car until it run out of battery and tried to land, in exactly this moment (video) signal turned off. It landed in the middle of a sugar cane field..

Since I was just 200 m far away I ran to the location it was supposed to be and the I got connected to the drone, saw the live view and everything, but than it turned off and I couldn’t find it in 6 hours searching :/

Now I have some questions for keep on searching tomorrow... I have the track of the whole flight, very precise I think (17 satelites when tracking was finished). The last cordinates of the flight record are more or less 20 meters away from the cordinates shown on “find my drone” (20 meters in (last) flight direction (against the wind))

1. Does the drone loose (satelite) signal when its on the ground? (Reason for wrong coordinates on”find my drone”?)
2. At what moment does DJI stop the flight record? At the moment it turns of the motor? So it got in contact with the sugar cane and immediatly turned of the motor and stoped recording?

Many thanks for any tips!!!
Tip 1: don’t fly in high winds
 
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C.h.gogo

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We are 4 persons searching right now and without sucess until now...
what about the “obstacle avoid” during the forced landing? The sugar cane is 3-4meter high... don’t know if the last VPS altitude was meassured from the ground or top of the canes... Could it be that at last point of signal it tried landing but got up again because of the “obstacle avoid” setting?

Does the drone stop its propelers/ flight engine immedeatly after first contact with an obstacle (sugar cane)?

We gonna focus and have a very detailed eye close around the two locations: last signal and your estimated landing location
 

sar104

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We are 4 persons searching right now and without sucess until now...
what about the “obstacle avoid” during the forced landing? The sugar cane is 3-4meter high... don’t know if the last VPS altitude was meassured from the ground or top of the canes... Could it be that at last point of signal it tried landing but got up again because of the “obstacle avoid” setting?

Does the drone stop its propelers/ flight engine immedeatly after first contact with an obstacle (sugar cane)?

We gonna focus and have a very detailed eye close around the two locations: last signal and your estimated landing location
As I said - I would look first around the "Find my Drone" coordinates (say a 5 meter radius circle) and then work back towards my estimated landing point. The coordinates you got on reconnection should be accurate. If you don't find it then increase your circle to 10 meters, etc.

Make sure that you are at the correct coordinates - what kind of GPS device are you using to find that precise location?
 

C.h.gogo

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We are using two iPhone SE for location... yesterday we searched precisly the area of “find my drone” a radius of 5 meters very very detailed... and several more meters...

As mentioned and researched the GPS Signal when it was already on the ground could be incorrect because maybe it is upsidedown and weak signal...
 

sar104

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We are using two iPhone SE for location... yesterday we searched precisly the area of “find my drone” a radius of 5 meters very very detailed... and several more meters...

As mentioned and researched the GPS Signal when it was already on the ground could be incorrect because maybe it is upsidedown and weak signal...
You had the live camera view - presumably you could tell if it was upside down. Either way, those two locations are very close together - the chances of it being outside a 10 meter radius from one of those points is extremely small. Are your iPhones consistently taking you to the same spot with those coordinates?
 

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