Curious auto land problem. Almost lost the A/C.

[bsartist]

Took a long flight yesterday. I think I poorly judged the headwind on the return. Yeah I should know way better! But that's not the point. I put it into sport mode and hoofed it on back as quickly as I could. As I got a few thousand feet away from home, it initiated an auto land. I thought I could push the throttle up to hold altitude and make it home but it wouldn't respond to that input and just kept descending eventually into a tree (after that it apparently fell down through the tree and to a soft landing on the ground. 3 busted props only damage).

The log (link attached below) is curious as it was at only down to 14% when it just starts warning me that it will auto land in 16 seconds. 16 seconds later it indeed switches to auto land and THEN claims I'm in a no-fly zone all of a sudden. I am not. I fly through this area all the time and pretty much flew through it on the outbound leg without an issue*. Yeah there is nominally a seaplane "base" charted in the middle of the lake but it's not in use and has never caused a no-fly zone issue. I guess the NFZ warning is why it went into auto land? And why it ignored my throttle. But why didn't it call out the NFZ before it initiated auto land? The whole thing seems strange to me. Making stupid mistakes on my own part is one thing. But I don't like it when the thing appears to have a mind of its own and won't let me control it. (By the way the multiple "command failed" warnings were the result of me tapping the cancel auto land on the screen out of desperation. I didn't really think it would let me cancel. Especially thinking at the time that it was a low batt auto land.)

Here is the log. Any thoughts would be appreciated. DJI Flight Log Viewer - PhantomHelp.com

*Edit: Another reason why I believe the seaplane "base" is not the culprit is because I had finished flying through that area and was over land by the time the NFZ warning came up.

 

[sar104]

Auto land was initiated because it thought it was in a NFZ. I cannot see any such restriction in the DJI geo system though. Very strange.

 

[Fly Dawg]

@bsartist .....Strange indeed. This is the closest I saw to the flight area. But even then it should not engage autoland.

 

[Ansia]

I've gotten notifications about possible RTH failure if flown by a NFZ. I don't k ow if it was the same problem you had.

 

[bsartist]

I've gotten notifications about possible RTH failure if flown by a NFZ. I don't k ow if it was the same problem you had.View attachment 109904

No. The problem here was that it suddenly and without explanation declared an NFZ where one did not exist. And then invoked auto land as a result.

 

[Ansia]

No. The problem here was that it suddenly and without explanation declared an NFZ where one did not exist. And then invoked auto land as a result.

Well that is a scary thought, that the drone thinks it suddenly entered a NFZ.

 

[bsartist]

Well that is a scary thought, that the drone thinks it suddenly entered a NFZ.

Indeed!!

 

[Nickatnite]

No. The problem here was that it suddenly and without explanation declared an NFZ where one did not exist. And then invoked auto land as a result.

Wasn't it giving autoland warnings before the NFZ message ? Glad you made it over the water and recovered it ! Seems like a battery/to far to make home point issue. NFZ /app anomaly. Problem is, loosing confidence with battery/bird/system to fly next time, especially over water ! Looks like a beautiful flight, love to see the footage.

 

[Ansia]

Wasn't it giving autoland warnings before the NFZ message ? Glad you made it over the water and recovered it ! Seems like a battery/to far to make home point issue. NFZ /app anomaly. Problem is, loosing confidence with battery/bird/system to fly next time, especially over water ! Looks like a beautiful flight, love to see the footage.

The flight log clearly stated that it auto landed due to a NFZ.

 

[bsartist]

Wasn't it giving autoland warnings before the NFZ message ? Glad you made it over the water and recovered it ! Seems like a battery/to far to make home point issue. NFZ /app anomaly. Problem is, loosing confidence with battery/bird/system to fly next time, especially over water ! Looks like a beautiful flight, love to see the footage.

Lake is frozen. But if this happens over the lake in warmer weather I’m losing the bird.

Yes as Ansia says below, it does appear to autoland due to NFZ and not battery as battery at 14% I don’t think triggers autoland. I think it has to be below 10%. Maybe lower. And the fact that I could not hold altitude during autoland with up throttle tells me it wasn’t a low batt autoland.

What is puzzling and confusing about the warnings is that, as you point out, it Gabe two autoland warnings in advance and didn’t mention NFZ until 16 secs later when it actually started the autoland. But maybe that’s how it works. I don’t know. I’ve never flown in an actual NFZ so haven’t seen the behavior in real life.

I should comment that I do see NFZ warnings when I start the AC it before I acquire enough satellites. Says I can’t takeoff in a NFZ. But as soon as I get enough sats for it to switch to GPS mode, that warning goes away and I can takeoff.

 

[bsartist]

I did some more testing and there is definitely funky going on with respect to me being somewhat close (within 5 miles) of that defunct but charged seaplane base. Not sure if it relates to my autoland problem but it seems suspicious.

When I power up near my house (within the 5 mi. of the “airport”) I initially get “cannot takeoff” while it’s acquiring sats and does not yet have GPS mode (sats OPTI). I tap that warning and check status. Sure enough sats no fly zone.

Once enough sats are collected and GPS mode turns on and green, home point is updated and I’m cleared for takeoff.

Is this a deliberate design? I’d think either I’m in an NFZ or I’m not.

I drove well outside the 5 mile radius and powered up the aircraft. No NFZ warnings.

 

[Ansia]

I fly quite often within the 5 mile radius of an airport and I only get the NFZ message after sat lock on both my v1.0 and v2.0.

 

[JSKCKNIT]

Definitely some weird stuff going on on your return leg for that flight! I've yet to see a DJI explanation for GPS position NoMatch warnings. I wonder if that's why it said restricted zone?

1. I read a review a couple months back and the author of the article had the same issue. He flew out over water with no problem, on return, it gave a restricted airspace warning (Presidential visit) and auto landed on the side of an unreachable part of a mountain. If I find the article, I'll update this.
2. If you didn't change the critical battery warning setting, default is 14%. It can be lowered to 10%. As you already know, at this point it will start to autoland. Normally you can do as you said and apply throttle to maintain altitude, slow descent. I believe it should have spit out a warning and shown up on the flight log that you reached critical battery level. I didn't see that in your log.
3. According to DJI, When a UAV flies near the boundary of a Restricted Zone, it will automatically decelerate and hover in place.
4. However, I think combining the critical battery level and it intermittently sensing a restricted zone, it autolanded, instead of hovered.

edit: Here's that article: I was going to review a $1,200 drone, but I lost it in Hawaii — here's what happened

 

[bsartist]

Definitely some weird stuff going on on your return leg for that flight! I've yet to see a DJI explanation for GPS position NoMatch warnings. I wonder if that's why it said restricted zone?

1. I read a review a couple months back and the author of the article had the same issue. He flew out over water with no problem, on return, it gave a restricted airspace warning (Presidential visit) and auto landed on the side of an unreachable part of a mountain. If I find the article, I'll update this.
2. If you didn't change the critical battery warning setting, default is 14%. It can be lowered to 10%. As you already know, at this point it will start to autoland. Normally you can do as you said and apply throttle to maintain altitude, slow descent. I believe it should have spit out a warning and shown up on the flight log that you reached critical battery level. I didn't see that in your log.
3. According to DJI, When a UAV flies near the boundary of a Restricted Zone, it will automatically decelerate and hover in place.
4. However, I think combining the critical battery level and it intermittently sensing a restricted zone, it autolanded, instead of hovered.

edit: Here's that article: I was going to review a $1,200 drone, but I lost it in Hawaii — here's what happened

Interesting read. Thanks!