“I’ve just upgraded the DJI Go4 app, I’m going out for a flight.”

Famous last words.

Magic Air
Motorola Droid Razer cell phone (without ability to call and receive) used as the controller

After doing the preflight (14 satellites) I lifted off and climbed to 300 feet and headed due south for about 500 yards and still in line of sight. As I approached the point where the Mavic Air would not be visible against the clear blue sky (and the background would be a mountain) my cell phone turned itself off.

“Oh no.”

When I last checked about 80% battery and RTH Time was 1 min 30. I rebooted the phone but was not able to get it to connect to the Mavic Air.  I left the RTH location and boarded my vehicle with the controller on the dash, and drove within about 100 yards away from where I thought Mavic Air should be. I was now maybe 50 feet lower in elevation that RTH point. I could not see the Mavic Air against the mountain terrain.

I heard the low battery sounding, and scouring the sky, could not locate it. I couldn’t connect to the drone and waited for the low battery sound to end.

I opened the DJO Go app and used the Find My Drone location. That location was not accessible by the time I got there as darkness would hamper my search. Returning to the house, a search of the RTH point did not locate the drone.

Tomorrow morning I plan to search the Find My Drone location. As I understand, that’s the last transmitted position of the drive.

Is that where it went down, or is that the position at the time of the last communication with my controller?

The flight log for the downed flight is not present in the DJI Go4 app. While a similar flight for yesterday exists, there is no flight data from my “downed” flight. Is there a means to extract that? A search of the forums didn’t help, I may not have used the correct search string as I became frustrated.

Going forward, tomorrow morning I plan to hike into the wilderness where the Find My Drone is last reported. But, if that’s the last transmitted location, then the drone coukd be anywhere between there and the RTH location. Is that correct?

Your guidance is appreciated.

my cell phone turned itself off.

When I last checked about 80% battery and RTH Time was 1 min 30. I rebooted the phone but was not able to get it to connect to the Mavic Air.  I left the RTH location and boarded my vehicle with the controller on the dash, and drove within about 100 yards away from where I thought Mavic Air should be. I was now maybe 50 feet lower in elevation that RTH point. I could not see the Mavic Air against the mountain terrain.
Losing the phone does nothing to your signal connection.
As long as the controller was switched on and connected, the drone would have just hovered waiting for you to do something.

You could have continued flying or activated RTH from the controller, even with the phone off..
Low battery RTH should have initiated  as the battery level became lower and the drone should have attempted to RTH.
RTH succcess would require no strong headwind issue and no obstacles on the RTH path.

Tomorrow morning I plan to search the Find My Drone location.
Is that where it went down, or is that the position at the time of the last communication with my controller?
It's the last location that the app (not the controller) had contact with the drone

The flight log for the downed flight is not present in the DJI Go4 app. ..  there is no flight data from my “downed” flight. Is there a means to extract that?
That would be very unusual. Has it turned up yet?

I plan to hike into the wilderness where the Find My Drone is last reported. But, if that’s the last transmitted location, then the drone coukd be anywhere between there and the RTH location. Is that correct?
Probably (depending on the wind) ... if you can find your flight record it might provide some information to fill in some blanks.

Thank you for your response.

The controller was on the entire time. When the phone turned "off" upon reboot the warning was similar to "Aircraft disconnected", I did not press the RTH on the controller. On prior flights when I have lost signal, the signal has been reacquired as the Mavic Air RTH. On those occasions both the controller and cell phone display remained on, and that was what I relied upon in this instance. When the Mavic Air did not reconnect, that was when I drove after it, hoping to shorten the distance for signal re acquisition.

If the Mavic Air attempted to RTH on low battery, it had no vertical obstructions until arriving at the home point. I cant recall what the exact time time needed was displayed for RTH but it was more than the Low Battery warning. No headwind, very little wind at all and there was wasn't a lot of drift at 300 feet on the outbound leg.

Referencing this article:   https://store.dji.com/guides/how-to-use-the-djis-return-to-home/

The Mavic Air was without signal more than 20 seconds for Failsafe RTH. I had previously practiced in an open field this situation and had the RTH height at 120ft. Other than the cell phone turning off, this event was similar to previous examples, but in those, I had reacquired signal before the Mavic Air reached the RTH location. I did not reacquire signal on this flight.

12 hours after the flight and the next calendar day the flight data has still not arrived on my phone.

Actions:
1) I plan to go to the the location of the Find My Drone, which is about the position at the time of the last communication. If it hovered till low battery then landed, I may find it. Once I arrive at the last known point, I'll activate the "Enable Indicator Flashing and Sound Alert", I do not know if that will work as the Mavic Air is out of power. I suspect action this will not be a recovery, but as it is public land, I have to get their before someone else.
2) On my return, I plan to search the area of the launch point, which is the RTH location. If the Mavic Air lost communication and after the elapsed time, it had ample battery to effect a Failsafe FTH.  A quick search last night in the dark did not locate it. This location is private land and I can take my time conducting a search without concern for the public.

PioneerXi Posted at 8-23 04:10
Thank you for your response.

The controller was on the entire time. When the phone turned "off" upon reboot the warning was similar to "Aircraft disconnected", I did not press the RTH on the controller. On prior flights when I have lost signal, the signal has been reacquired as the Mavic Air RTH. On those occasions both the controller and cell phone display remained on, and that was what I relied upon in this instance. When the Mavic Air did not reconnect, that was when I drove after it, hoping to shorten the distance for signal re acquisition.

12 hours after the flight and the next calendar day the flight data has still not arrived on my phone.
The flight data should already be there.
It doesn't have to "arrive" from anywhere.

Have you looked for the text file in your phone ?
You'll find instructions to find it if you follow this link:  https://www.phantomhelp.com/logviewer/upload/
Is there a .txt file there for the date and time of your last flight?

Thank you for assistance of what is becoming a long day.

At dawn I went out and hiked “up” to the last know position. The area is a vertical rock face. I was not equipped for the last 10 feet which was a 30 foot climb. Had the MA come down there, I’d have found it on the first level ground. I did not find it. A wider search on the RTH path did not locate it or evidence of destruction.

Per the original post photo, the flight data is not documented. Following your link, I had to use SD Refresh and located a text file on the cell phone, but it was not visible when connected to the PC. The flight data folder of the cell phone  is absent on the PC. The file exists per the below photo.

I can see the downed flight data but when asked to open it with Chrome, html editor or office, I get pages of ....symbols. (Below photo) I do not have the knowledge to extract the file visible on SD Reader, hidden otherwise, to be used for diagnosis.

It has been a battle today.

I located a text file using airapp

https://app.airdata.com/share/FEiaUr

...but when I uploaded it into Phantonhelp  it did not present the same imagery as some of the other incidents reported on the forums.

PioneerXi Posted at 8-23 14:16
It has been a battle today.

I located a text file using airapp

Here's a summary of your flight data: https://www.phantomhelp.com/LogViewer/GPT7CI1TB1NXB8LKWXAC/

It only shows the data up to the point where the app dropped out and what happened after that is not certain.
Losing the phone and app doesn't drop the control connection and as you didn't switch off the controller, it may have still had contact for some time and the drone would have been hovering.
You mentioned hearing what you called the low battery sound?
That's only possible if the controller was still connected.

If you had moved the joysticks after the app was lost, that would have flown the drone away from where the app was lost, but we have no data to indicate where.

The data indicates no significant wind for the RTH and there are no obstacles on the RTH path.
When the app was lost the drone was very close to the steep rocky slope to the south.
It was still approximately 200 feet higher than the ground where the drone was last recorded.
If it stayed at the same altitude it would have had to fly a further 400+ feet to run into the rising terrain.

Thank you for your work.

May I draw on your knowledge further?

Per the Phantomhelp log, at 5.23 the Downlink was restored. What does that mean?

I definitely heard the low battery sound while the phone was not connected. My focus at the time was on reconnecting and not moving the MA.  The log shows strong aircraft interference at 3.36 and the loss of signal is the 5.30, that's almost 2 minutes in the same area. In that 2 minute span, would your opinion be that the MA was hovering prior to loss of signal?

If the MA was hovering, and continued to hover, when the battery ran out, with no control, would it have attempted to land in that area? As it descended, do you know if the MA would attempt to find "level" ground before the battery ran out, or would it just come down?

The terrain doesn't allow me to climb higher if the MA proceeded south, but if it hovered, the area east and north of the last known location appears to be the best starting point for the next search.

Again, thank you for your time on this.

PioneerXi Posted at 8-23 19:29
Thank you for your work.

May I draw on your knowledge further?

An update.

Thanks to the work of Labroides, I parked on the interstate near the last recorded position and conducted a two hour search without success.  On returning to my vehicle, met the Highway Patrol who had ticketed my car for parking on the shoulder. When they asked questions and I explained, they rescinded their notice, and asked me not to park there again.

I went back a week later and hiked in from the other side, the same day as California's Valley Fire began. It cut off my entry walk so I exited out of the fire zone via the interstate.

A search near the home point failed to locate the MA, and I accessed a point that would allow me to overlook the rooftops of residency's had the MA attempted to RTH. I could not see it on the rooftops.

I made a report to the Sheriff (local jurisdiction) who asked why. When I informed them that not knowing where it came down, I didn't know if it had crashed and caused damage. They took a police report for "Lost or Stolen".

I conducted another search adjacent to the RTH area where some trees were located. The residency that occupied the land was recently vacated so it allowed me to enter and scour from below the trees. No success.

I was adamant that the MA should have RTH, but, as I had not remained at the RTH location in an attempt to reconnect, I had no seen whether it did.

I was on the front porch this morning looking out over the damage that the Valley Fire had done to adjacent land, thinking about the opportunity for aerial recon of fencelines for property owners in the area. I looked towards the point that I had accessed to overlook the rooftops and at eye level was the MA stuck in the tree adjacent to my porch - about 12 feet from the RTH point. It had been obscured by the tree when I was on the elevated point and at the RTH point. Its final resting position was about 12 inches from my own residency roof line.  Stepladder, short reach and the MA was retrieved.

No apparent damage. No propeller damage. No "fall from the sky" scratches that I had seen previously on devices that had "crashed" within a tree.

It looks like that on the approach to RTH it attempted to land on my roofline, and just skidded off to be gently caught by an adjacent tree branch.

I was lucky to recover it, as the MA is (almost) no longer available for purchase in my area.

I was also lucky that it did in fact RTH (almost) and that I located it on my own property, 22 days after it went MIA.

I was also lucky for Labroides to dissect where it was last reported, and that I was able to put together enough Search and Rescue that if I did not recover it, it wasn't for trying.

Cause of incident: equipment failure and pilot error and not having practiced good judgement. I shouldn't have left my location when the connection was broken and I should have pressed the RTH on the controller, safe in the knowledge there was sufficient battery power - then waited to see and hear the MA come home. Even if it didn't return to the exact position, I would have seen or heard it and could have same myself 22 days.

Again, thank you

First or all, I'm really happy for you that you got your drone back.  It sounds like it did exactly what it was supposed to do.  Hovered and waited around until battery was low enough that it did a low battery RTH.  I'm going to suggest that you read the crash post I did a little over a week ago because we BOTH need to learn (or re-learn) a habit.  That is if the phone crashes, the controller is still live and the RTH button on the controller should bring it back home.  Here is my story:
https://forum.dji.com/forum.php?mod=viewthread&tid=224044

K6CCC Posted at 9-15 14:34
First or all, I'm really happy for you that you got your drone back.  It sounds like it did exactly what it was supposed to do.  Hovered and waited around until battery was low enough that it did a low battery RTH.  I'm going to suggest that you read the crash post I did a little over a week ago because we BOTH need to learn (or re-learn) a habit.  That is if the phone crashes, the controller is still live and the RTH button on the controller should bring it back home.  Here is my story:
https://forum.dji.com/forum.php?mod=viewthread&tid=224044

Read your story, thank you.

I fully agree,  use the controller for RTH.

and don't panic. When I left to "chase" my MA, I should have remained steadfast and worked the problem instead of attempting to salvage a situation I had not fully processed.