I took my Mavic Air up to Big Cottonwood canyon yesterday here in Utah and about 5 mins into my flight the drone just started to drop in altitude like it was coming down to land. It was smooth and slow, but I tried everything to keep it up and nothing worked. I never lost connection and had it in sight for all but the landing where I lost connection when it was about 10 feet from the ground. LUCKILY I was able to land it near a road down on the other side of the canyon and then ran down the mountain and found it about 30 mins later. It recorded the entire flight and there was no indication or warning as to why this may have happened. Anyone else seen this issue before?

Super confused and nervous that it’s gonna do this again, I just might not be so lucky next time to find a decent landing spot.

If you don't mind, please upload your flightrecord to this site http://www.phantomhelp.com/LogViewer/Upload/ and share the link with us. It might provide some answers to what has happened. You will find the flightrecord in a DJI subfolder on your mobile device named "Flightrecord".

What was this canyon like?  If it is a deep narrow canyon, you could easily lose GPS.  What it would do then, I don't know.  I've never lost GPS signal, except intermittently when I fire it up in the house for testing or upgrades.

AG0N-Gary Posted at 2018-3-12 13:38
What was this canyon like?  If it is a deep narrow canyon, you could easily lose GPS.  What it would do then, I don't know.  I've never lost GPS signal, except intermittently when I fire it up in the house for testing or upgrades.

If GPS is lost it will just hold altitude and drift with the wind. GPS don't change how altitude work as it is barometric control.

Post the log please

Perhaps restricted airspace and the drop in altitude a reason.......  (closer you get to a NFZ your altitude will decrease)

Here's the flight record... http://www.phantomhelp.com/LogViewer/W9C3T2KORL5SSS4FDHT7/

Wachtberger Posted at 2018-3-12 13:32
If you don't mind, please upload your flightrecord to this site http://www.phantomhelp.com/LogViewer/Upload/ and share the link with us. It might provide some answers to what has happened. You will find the flightrecord in a DJI subfolder on your mobile device named "Flightrecord".

http://www.phantomhelp.com/LogViewer/W9C3T2KORL5SSS4FDHT7/

n8blogg Posted at 2018-3-14 08:15
http://www.phantomhelp.com/LogViewer/W9C3T2KORL5SSS4FDHT7/

Thank you very much and gosh, I have never seen anything similar before I must admit. You seem to have a seriously defective battery there and you should immediately open a support case with DJI for this: https://www.dji.com/support
Luckily your flight ended well and without damage to your Mavic Air! From your description of the incident I conclude that your MA tried to auto-land because of the defective battery. What surprises me however is the fact that it did not issue any warnings as you report it.

n8blogg Posted at 2018-3-14 08:15
http://www.phantomhelp.com/LogViewer/W9C3T2KORL5SSS4FDHT7/

Looking at your log it’s fairly clear why aircraft landed where it did, although you seem to be having a problem with battery this was not the reason your aircraft landed where it did

1/ At 6.22 minutes RTH was activated distance from home 2631 ft
2/ Aircraft landed 1062 ft from homepoint
Why, well when Aircraft was in RTH controller was pulling down on throttle 100% until aircraft landed aircraft was still moving towards homepoint but with Mavic Air there is a new feature we haven’t seen in other aircrafts , in RTH we can control both speed by pushing elevator and altitude by pushing throttle, if you look at log you will see controller moving left stick 100% down until aircraft landed.

hallmark007 Posted at 2018-3-14 14:51
Looking at your log it’s fairly clear why aircraft landed where it did, although you seem to be having a problem with battery this was not the reason your aircraft landed where it did

1/ At 6.22 minutes RTH was activated distance from home 2631 ft

Thank you very much hallmark007 for having explained this! I actually had overlooked the RTH part of the log because I was so puzzled about the battery issue. Still a lot to learn for me, thank you again!

Thanks for the feedback from both of you. I obviously didn’t Include  enough detail in my initial post....after a minute or so of the drone descending on its own, I hit the RTH button to see if that would stop the descent. Since it did not, I turned it off after about 30 seconds and as the drone continued to decend, I landed it manually in a safe spot. The drone didn’t land on its own, I tried the RTH as kind of a last ditch effort to see if it would quit losing altitude, but to no avail. Unless I completely misunderstood your post hallmark007, the RTH had nothing to do with my drone descending on its own.

n8blogg Posted at 2018-3-14 16:41
Thanks for the feedback from both of you. I obviously didn’t Include  enough detail in my initial post....after a minute or so of the drone descending on its own, I hit the RTH button to see if that would stop the descent. Since it did not, I turned it off after about 30 seconds and as the drone continued to decend, I landed it manually in a safe spot. The drone didn’t land on its own, I tried the RTH as kind of a last ditch effort to see if it would quit losing altitude, but to no avail. Unless I completely misunderstood your post hallmark007, the RTH had nothing to do with my drone descending on its own.

Your Aircraft was at a steady 350 ft altitude, it never lowered this altitude until you pulled down on the throttle and when you were in RTH mode your Aircraft was also heading home as well as you trying to land.
But nowhere in your flight log does it show your aircraft loosing altitude unless by stick movements by you, the only time it reduced altitude was when it was at 350 ft and you pulled back throttle.

n8blogg Posted at 2018-3-14 16:41
Thanks for the feedback from both of you. I obviously didn’t Include  enough detail in my initial post....after a minute or so of the drone descending on its own, I hit the RTH button to see if that would stop the descent. Since it did not, I turned it off after about 30 seconds and as the drone continued to decend, I landed it manually in a safe spot. The drone didn’t land on its own, I tried the RTH as kind of a last ditch effort to see if it would quit losing altitude, but to no avail. Unless I completely misunderstood your post hallmark007, the RTH had nothing to do with my drone descending on its own.

At 1,20 mins you were at altitude approx 350ft until 5.28 , from 5.28 until end of flight 9.37 mins you will see from your log that you were pulling down on the throttle. And it’s only during this time that Aircraft was dropping in altitude.

hallmark007 Posted at 2018-3-15 03:07
At 1,20 mins you were at altitude approx 350ft until 5.28 , from 5.28 until end of flight 9.37 mins you will see from your log that you were pulling down on the throttle. And it’s only during this time that Aircraft was dropping in altitude.

hallmark007, thanks for the feedback. I definitely understand what you're seeing on the flight log, but I wasn't holding down on the joystick to make it descend. In the log you can see a few times, when the drone was at 0 mph I was letting off of ALL controls to see if it was still dropping, and it was. It was essentially responding as if the joystick was stuck in the down position to make the drone descend, although the stick wasn't stuck or anything.  

I'm certainly no drone expert or anything, but I promise you I'm not stupid enough to hold down the joystick and then ask why my drone was descending. I was actually pushing the joystick up for part of the time to see if it would respond and and climb in altitude as I moved it back towards us a little bit. My cousin (who has flown a mavic pro for a few years)  was watching this as well and was equally as concerned/confused that I wasnt controlling the descent.

n8blogg Posted at 2018-3-15 09:51
hallmark007, thanks for the feedback. I definitely understand what you're seeing on the flight log, but I wasn't holding down on the joystick to make it descend. In the log you can see a few times, when the drone was at 0 mph I was letting off of ALL controls to see if it was still dropping, and it was. It was essentially responding as if the joystick was stuck in the down position to make the drone descend, although the stick wasn't stuck or anything.  

I'm certainly no drone expert or anything, but I promise you I'm not stupid enough to hold down the joystick and then ask why my drone was descending. I was actually pushing the joystick up for part of the time to see if it would respond and and climb in altitude as I moved it back towards us a little bit. My cousin (who has flown a mavic pro for a few years)  was watching this as well and was equally as concerned/confused that I wasnt controlling the descent.

I’m not casting aspersions on anyone, I take you at your word, then the problem is that log shows aircraft descending it also recorded right stick throttle in the downward position, only thing I can think of is you might need to do a RC stick calibration, once you go into calibration you should be able to see if there are any anomalies, also it is possible that RC sticks can be affected by magnetic interference, but I’m not so sure in this case.

And let's not forget about the battery issue that DJI should have a look at. By no way would I fly again with this battery should the flightrecord data analysis turn out to be correct.

Wachtberger Posted at 2018-3-15 10:44
And let's not forget about the battery issue that DJI should have a look at. By no way would I fly again with this battery should the flightrecord data analysis turn out to be correct.

That definitely makes sense, not sure what's going on w that battery but I'm going to send DJI a message w this flight log and let them have a look. Thanks!

hallmark007 Posted at 2018-3-15 10:40
I’m not casting aspersions on anyone, I take you at your word, then the problem is that log shows aircraft descending it also recorded right stick throttle in the downward position, only thing I can think of is you might need to do a RC stick calibration, once you go into calibration you should be able to see if there are any anomalies, also it is possible that RC sticks can be affected by magnetic interference, but I’m not so sure in this case.

Sorry if I came off defensive, that was definitely not my intent. I know you have a lot more experience than I do with all of this, so I really do appreciate the input and advice. I'll try re-calibrating the stick and hopefully I don't run into this issue again. Makes me nervous to take it over any body of water now though! I need to get it sorted out soon, I've got a trip to St. Thomas in a few weeks where I will DEFINITELY want to get some awesome footage. Thanks again for the help!

Wachtberger Posted at 2018-3-14 13:48
Thank you very much and gosh, I have never seen anything similar before I must admit. You seem to have a seriously defective battery there and you should immediately open a support case with DJI for this: https://www.dji.com/support
Luckily your flight ended well and without damage to your Mavic Air! From your description of the incident I conclude that your MA tried to auto-land because of the defective battery. What surprises me however is the fact that it did not issue any warnings as you report it.

Since I really haven't had any previous experience looking at flight records, I'm not totally sure I understand what you're seeing in there that would indicate a defective battery. Do you mind elaborating on what you're looking at as well as what I should be expecting to see? I looked at a few other flight records to try to compare and see what might be different about this one, but didn't see anything that appeared any different than other records. I just want to be able to explain the issue to DJI from what I'm seeing on there. Thanks a lot for your help on this!

Cell 3 on your battery is dead. Replace it and try again. I would not fly with that battery.

Exchange that drone, it's clearly defective in more than one way.

n8blogg Posted at 2018-3-15 13:44
Since I really haven't had any previous experience looking at flight records, I'm not totally sure I understand what you're seeing in there that would indicate a defective battery. Do you mind elaborating on what you're looking at as well as what I should be expecting to see? I looked at a few other flight records to try to compare and see what might be different about this one, but didn't see anything that appeared any different than other records. I just want to be able to explain the issue to DJI from what I'm seeing on there. Thanks a lot for your help on this!

It's quite easy, look at the columns relating to battery voltage and cells (big deviations and jumps). DJI will request you to export your blackbox data and make it available to them. You can easily do this with DJI Assistant https://www.dji.com/mavic-air/info#downloads.

Wachtberger Posted at 2018-3-15 14:45
It's quite easy, look at the columns relating to battery voltage and cells (big deviations and jumps). DJI will request you to export your blackbox data and make it available to them. You can easily do this with DJI Assistant https://www.dji.com/mavic-air/info#downloads.

That makes sense. I was looking at the deviations, but wasn't sure exactly how to translate that. Thanks for the clarification. I bought it at Best Buy, so I'm not sure if they would be able to do anything about it, but I'm hoping DJI can help.

n8blogg Posted at 2018-3-15 14:51
That makes sense. I was looking at the deviations, but wasn't sure exactly how to translate that. Thanks for the clarification. I bought it at Best Buy, so I'm not sure if they would be able to do anything about it, but I'm hoping DJI can help.

If you can still return it, simply do that and get a new one! That would be by far the easiest way out of the problems.