Mavic Air just dropped from the Sky. -Recovered, but wondering why?

[lakeflyer]

I was flying my Mavic Air at about 700 feet up I estimate. It was high enough that it was still visible, but I could almost make out which direction it was facings with VLOS. I had perfect VLOS and was standing adjacent to some low hanging trees when the drone just out of nowwhere with no warning of weak signal fell from the sky. All components were at near full charge -drone -reciever -android phone. The drone just fell from the sky. It fell through a tree -which broke its fall and I recovered it in perfect condition. Notably, the video file that was being recorded at that moment was unseable. When I tried to view the video file I got an error message that the file was unuseable. If this were a case of Signal loss, doesnt the Mavic Air know enough to maintain position until the user can adjust to a position to restore signal? There was only a small tree I was standing under, and I might have moved the controler away from direct pointing at the drone for only a moment. -cant be sure of that either. But it was no more that a few hundred yards away ever, and with in VLOS.... while I was standing near a cherry tree. Mavic Air without any warning just dropped from the sky. Video feed went dead. All other videos were recoverable, except the video during the shut down which when I try and view says "error"

 

[RayOZ]

Post flight logs.
Is the battery still in the AC when you retrieved it, cos it seems like it might have popped out mid flight.

 

[lakeflyer]

Battery was intact and snapped in on retreival.. Remote was fully charged, so was my Samsung Galaxy Note 5. In fact, I rebooted everything and flew again the rest of the day. I swear I was looking right at the drone -perhaps less than 300 yards away, and another 150 yards in the air with only some short trees on my right when it just fell from the Sky. I lost a the left front foot and the left rear foot and the Mavic air takes off and flys like it doesnt matter. I would like to restrore the drone and hoping I can do it with parts myself -if anyone can give me some insight given the pictures I posted I would be greatful. Thanks again

 

[InvisibleName]

Battery was intact and snapped in on retreival.. Remote was fully charged, so was my Samsung Galaxy Note 5. In fact, I rebooted everything and flew again the rest of the day. I swear I was looking right at the drone -perhaps less than 300 yards away, and another 150 yards in the air with only some short trees on my right when it just fell from the Sky. I lost a the left front foot and the left rear foot and the Mavic air takes off and flys like it doesnt matter. I would like to restrore the drone and hoping I can do it with parts myself -if anyone can give me some insight given the pictures I posted I would be greatful. Thanks again

You need to post your flight data - but no way loss of signal would make it fall out of the sky. Loss of signal between RC & MA just means it maintains it attitude until either RC connection is reestablished, or RTH kicks in based on whatever settings you preset.

 

[DJ Wes]

All other videos were recoverable, except the video during the shut down which when I try and view says "error"

If you wish to recover that video you may wish to try:

Repairing Corrupt DJI Video Files

I have used that software and it worked for me.

 

[Mrmund]

Did you "stop" recording before you shut down the aircraft?

 

[jonthecourier]

I fear you witnessed a power failure of some sort, but what I'm interested in is what sort of eyes do you have to be able to have VLOS with the bird at somewhere near 700 feet up when 400 ft is the advertised limit in the UK and USA perhaps if you had stayed to 400 ft you would have not had the accident.

 

[runeOfRune]

We can sit here for a month speculating, or OP can upload a flight log and we'll probably know in 15 minutes. Just saying.

 

[sar104]

....perhaps if you had stayed to 400 ft you would have not had the accident.

Are you worried that perhaps the aircraft crashed because it was scared of heights?

 

[Thomas B]

 

[lakeflyer]

We can sit here for a month speculating, or OP can upload a flight log and we'll probably know in 15 minutes. Just saying.

thanks... Im gonna use the link others have provided to try and recover the video and flight log and I'll post it here.

 

[lakeflyer]

I fear you witnessed a power failure of some sort, but what I'm interested in is what sort of eyes do you have to be able to have VLOS with the bird at somewhere near 700 feet up when 400 ft is the advertised limit in the UK and USA perhaps if you had stayed to 400 ft you would have not had the accident.

I cant say for certain how far off it was without the flight data and the video. But it was within VLOS and I could just barely tell which way the drone was oriented. Im a careful, resposible pilot. I'd say the tree it landed under was 100 yards from where I was standing and the drone was a good 100+ yards up. -By no means unreasonable. I was in full control when all of a sudden it just FELL. -damaging the feet on the left front and left rear.

 

[lakeflyer]

We can sit here for a month speculating, or OP can upload a flight log and we'll probably know in 15 minutes. Just saying.

I fear you witnessed a power failure of some sort, but what I'm interested in is what sort of eyes do you have to be able to have VLOS with the bird at somewhere near 700 feet up when 400 ft is the advertised limit in the UK and USA perhaps if you had stayed to 400 ft you would have not had the accident.

My bad.... by 700 feet Im referring to absolute distance to the drone from myself. There is no way I was up 700 feet. I was high enough to safely hover over a really old and big oak tree. Power failure. Thats interesting.

 

[lakeflyer]

Here is the Flight Log of the flight where the drone mysteriously fell from the sky. Im new to drones, but not RC or Lipo batteries. I've read the 3 cells voltage and voltage deviation records. They look normal and consistent. Smoothly ranging from .05 to .02

At the time of the crash (the last recorded position of the drone in the flight log) the drone was at Altitude 102Ft, and distance from home 117Ft. Battery 37%. The drone never went higher that 150ft or distance from home greater than 150ft. -So much for estimations!!! LOL

So much for battery failure to to unbalanced cells right? Looking at the google earth flight path Im tempted to wonder if I hit the tree located at the very last recorded position of the drone. BUT I was looking at the drone at the time it fell, and I could see sky between the top of the tree and the drone. I can still see it in my mind -the drone in open sky, hovering on moment, then the next moment it just all of a sudden fell like a dead bird.

Im going to run several more flights and battery packs at low flights. The crash broke the feet on the left front and rear. Im contacting DJI repair/support on Monday to arrange to send it back for those repairs. I'll also run this story by DJI and see what they say.

Thanks for your help guys.

 

[sar104]

Here is the Flight Log of the flight where the drone mysteriously fell from the sky. Im new to drones, but not RC or Lipo batteries. I've read the 3 cells voltage and voltage deviation records. They look normal and consistent. Smoothly ranging from .05 to .02

At the time of the crash (the last recorded position of the drone in the flight log) the drone was at Altitude 102Ft, and distance from home 117Ft. Battery 37%. The drone never went higher that 150ft or distance from home greater than 150ft. -So much for estimations!!! LOL

So much for battery failure to to unbalanced cells right? Looking at the google earth flight path Im tempted to wonder if I hit the tree located at the very last recorded position of the drone. BUT I was looking at the drone at the time it fell, and I could see sky between the top of the tree and the drone. I can still see it in my mind -the drone in open sky, hovering on moment, then the next moment it just all of a sudden fell like a dead bird.

Im going to run several more flights and battery packs at low flights. The crash broke the feet on the left front and rear. Im contacting DJI repair/support on Monday to arrange to send it back for those repairs. I'll also run this story by DJI and see what they say.

Thanks for your help guys.

There's no indication of what happened in that log - the record simply ends at a height of 31 m and a distance of 36 m. You might want to see what is in the mobile device DAT file - FLY077.DAT is the one that you need.

Mobile device DAT file: How to retrieve a V3.DAT from the tablet

 

[lakeflyer]

Here is the .DAT file from /MCDATFlightRecords for the flight in question. I am downloading DJI Assistant 2. Im assuming DJI Assistant 2 can open this file directly and read data? -And I wont need to conntect to the drone directly?

 

[lakeflyer]

I ran my DAT files from the flight on airstats.com and dowloaded the KML file and load it in Google Earth. Drone was clearly in mid flight when it "Dropped" like a rock. Battery Temp was 128.8F, 37% charge, .02 Voltage Variation. Im thinking Im going to fly several test flights at low altitude and close by, burn through several battery packs and study the .DAT files.

*** Any advice on what to look for in the reports I get at Airstats.com from the DAT files?




***Something happened where the yellow line ends, sending the drone to fall through that tree below breaking its fall:

 

[sar104]

Here is the .DAT file from /MCDATFlightRecords for the flight in question. I am downloading DJI Assistant 2. Im assuming DJI Assistant 2 can open this file directly and read data? -And I wont need to conntect to the drone directly?

Nothing obvious there either. The flight looks fine until it doesn't. There are numerous battery entries of the [38850 [L-BATTERY]get_cell_voltage_callback_ack failed!||] kind in the event stream, but that particular message seems to be fairly common, and may be unrelated. This looks like a sudden shutdown, possibly power loss or an FC crash but hard to distinguish from the data.

 

[runeOfRune]

Yeah, the logs just end, so everything points to some kind of power failure. Was the drone on when you recovered it, or was the battery shut down? Unless you actually clipped that tree, but the AC shouldn't have shut down anyway even if that's what happened...

Repairing Corrupt DJI Video Files

Oh wow, live555, that brings back memories!

 

[lakeflyer]

-DRONE WAS OFF WHEN I RECOVERED IT. NO LIGHTS WERE ON. As far as "or was the battery shut down" -I can't be certain. All I know is all power appeared to be OFF, no lights...etc... and the drone restarted/rebooted as normal for the next flight.

So... for the million dollar question: Is this a failure of the drone that qualifies for sending it back to DJI and not being charged for the repairs?? -The front left foot which contains an antennae was broken. There was nothing I did to cause the crash. Battery was still at 37%. I didnt hit an obstacle. I was under 400' and withing VLOS. I was using latest firmware and all DJI factory product.