DJI Mavic, Air and Mini Drones
Friendly, Helpful & Knowledgeable Community
Join Us Now

FOUND! Lost my Mavic Pro during storm

Yes critical battery voltage will cause the Mavic to Autoland. While doing so it is not a straight line downwards as the wind is still pushing the Mavic in the direction of the wind. So its not like a rock falling from the sky straight down. I believe that Sar104 has included that in the estimate with the + /- 3 degree's.

Search the area indicated. Then find your Mavic. Sing the Praises of Sar104 and consider this a teaching moment. I personally think Sar104 should monetize his assistance and start a Paypal Donation account . :) He has helped out many forum members out of the goodness of his heart resulting in many found Mavics. Truly selfless acts of kindness.
i agree!!!
 
@sar104 you're like the Walter White of drone whereabouts. I'd just be out there looking till I blacked out in the field. They say work smarter, not harder though so your skills on finding drones are definitely more advanced than mine haha!
 
@sar104 you're like the Walter White of drone whereabouts. I'd just be out there looking till I blacked out in the field. They say work smarter, not harder though so your skills on finding drones are definitely more advanced than mine haha!

Well let's not get too carried away, at least until (if) the OP has any luck finding it.
 
I’m seriously waiting for an update from the Op @sar104 they should have hired you to find mh370. No joke at all. Seems like you’d be the guy for the job. Op. Plz update everyone ASAP. May the force be with you op!
 
Yes critical battery voltage will cause the Mavic to Autoland. While doing so it is not a straight line downwards as the wind is still pushing the Mavic in the direction of the wind. So its not like a rock falling from the sky straight down. I believe that Sar104 has included that in the estimate with the + /- 3 degree's.

Search the area indicated. Then find your Mavic. Sing the Praises of Sar104 and consider this a teaching moment. I personally think Sar104 should monetize his assistance and start a Paypal Donation account . :) He has helped out many forum members out of the goodness of his heart resulting in many found Mavics. Truly selfless acts of kindness.
@Sar104="Mavic Whisperer" [emoji4]
 
  • Like
Reactions: Flapper and BD0G
Status?... Does it work?
 
Last edited:
MAN, YOU’RE A LEGEND!!!!

I have FOUND my drone at the EXACT spot where you speculated it should have landed!

I’m too happy and can’t thank you enough for your help, it would have been impossible to find it without your help!

THANK YOU soo much again!

Will upload detailed pictures shortly.

View attachment 39606

Good result. We had some advantages with this one - the wind field was pretty consistent and the battery depletion rate was consistent enough to have some confidence in the timing of autoland. I wish they all ended this well.
 
Why are you all wearing flip flops... you need some wellies for that journey!

Well done! What a great result!

Would be great if @sar104 could share their methods for working this out for ourselves, should the time come
 
  • Like
Reactions: Fried Toast
Why are you all wearing flip flops... you need some wellies for that journey!

Well done! What a great result!

Would be great if @sar104 could share their methods for working this out for ourselves, should the time come

It's not as complicated as it might appear, and the entire method is essentially described in post #32. In the case of a steady wind-induced drift in P-GPS mode, then once you have the .txt flight log converted you have access to all the necessary information. Specifically the following fields:
  1. OSD.flyTime: elapsed flight time in seconds
  2. CENTER_BATTERY.fullCapacity: full battery capacity in mAh
  3. CENTER_BATTERY.currentCapacity: current battery level in mAh
  4. OSD.latitude: decimal degrees
  5. OSD.longitude: decimal degrees
  6. OSD.xSpeed: velocity north in m/s
  7. OSD.ySpeed: velocity east in m/s
  8. OSD.height: altitude above home point in meters
  9. OSD.flycState.RAW: flight mode (P-GPS is 6, RTH is 15, ATTI is 1)
  10. SMART_BATTERY.landBattery: the FC's estimated battery percentage at which it will commence autoland
In P-GPS mode when uplink is lost the aircraft will attempt (or continue to attempt in this case) to RTH, and then autoland when the battery percentage (100 x CENTER_BATTERY.currentCapacity/CENTER_BATTERY.fullCapacity) decreases to the calculated minimum level from which it can land from its current altitude (SMART_BATTERY.landBattery). The time at which autoland will occur can be estimated by extrapolating the decreasing battery percentage until it meets the autoland level. In the graph that is the intersection of the dashed red line and the dashed orange line.

2018-06-05_[17-41-08]_02.png

Reading off the bottom time axis then gives the estimated autoland start time - in this case 1150 s. If it was drifting steadily before downlink is lost then that drift rate can be used to estimate where it will be at the autoland start point.

You can (a) use the latitude and longitude data (converted to distance north and east since lat/long is not linear on the ground) or the x and y speeds, either (b) directly (averaged at the end and multiplied by elapsed time to get distance) or (c) integrated with respect to time to give distance north and east and then extrapolated by linear fit to the appropriate time. If the aircraft is basically moving directly away from the home point you can also simplify the problem and (d) just use the calculated distance from home point field in the data (CALC.distance), extrapolating that from the last recorded point at the appropriate rate. I generally use either (a) or (d) depending on the situation.

Anyway - in the graph (d) is used, and the distance of the autoland point from the homepoint is found by extrapolating the distance data (blue) with a linear regression fit to the last part of the data when the aircraft was in RTH mode (dashed blue trace) to the 1150 s mark giving 9620 m. Then estimate the time required to autoland from the current altitude (need to take into account any change in ground elevation from the takeoff point) and add that to the time to get the estimated landing time since drift will continue during descent (around 30 s from 80 m at the default descent rate fo 3 m/s in this case). Bear in mind that the drift rate will likely decrease with altitude, and so this should be a bounding upper value. Extrapolating distance further to that time in this case gives 9985 m.

Direction of travel can be derived from the final averaged values of x and y speed, or estimated directly in Google Earth from the kml flight track. Then it's just a question of plotting the estimated track to the appropriate distance in Google Earth to find the estimated landing point, with some appropriate estimates for error in track direction, based on how steady the drift direction was at the end of the logged part of the flight.

The main source of error is an unsteady wind field, leading to variation in drift rate and direction. There is also an assumption that after the downlink is lost (end of the log) then either the uplink (control) is also lost or that the pilot doesn't send more control inputs (sticks or other commands) that will change the aircraft behavior.

I hope that helps.
 
Yeah thats not complicated at all !

Congratulations on the find! I knew you would find it with Sar104's help.

How many found Mavics is that now?
You should have a graphic of a Mavic with a found statement posted over the Mavic diagonally that you can post and update in your signature line. Indicating how many Mavics you have helped find.

Kinda like fighter pilots listed kills on the sides of thier planes.
 

Attachments

  • brain_explode.jpg
    brain_explode.jpg
    34 KB · Views: 61
Last edited:
Yeah thats not complicated at all !

Congratulations on the find! I knew you would find it with Sar104's help.

How many found Mavics is that now?
You should have a graphic of a Mavic with a found statement posted over the Mavic diagonally that you can post and update in your signature line. Indicating how many Mavics you have helped find.

Kinda like fighter pilots listed kills on the sides of thier planes.

OK - I agree that it involves a number of steps, but they are a well-defined progression of simple manipulations of the recorded data. There is no magic or even intuition involved, just the progressive application of high-school-level mathematics. This kind of stuff always looks more impressive at first glance when someone else does it, but if you follow the reasoning it's not really difficult. A data analysis and graphing package may be the prerequisite that stymies casual analysis by most people.
 
  • Like
Reactions: Rogat19
Hi Guys,

Have been flying today, the wind was high and couldn’t imagine it would go crazy high within seconds, altitude was about 100m, tried my best to bring it down manually and through RTH but it kept on going with the wind for 6500m distance until i lost connection.

I reached the place where it was disconnected and tried a search nearby but all in vain.

If I upload the flight record, is there any possibility to get any approximate location or any idea how far it could’ve gone from that location?

There are all fields in that area so i have a hope it can be found after some struggle.

Thanks in advance for the help.
Regards
Glad you found it!!
 

DJI Drone Deals

New Threads

Forum statistics

Threads
134,739
Messages
1,598,116
Members
163,239
Latest member
simon007
Want to Remove this Ad? Simply login or create a free account