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Long Distance Flight Scare

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Carlos56

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I get nervous flying my Mavic Mini over trees, because if it falls in the forest around here, there is a very good chance it’s going to be stuck 40 feet up somewhere, and I don’t think the neighboring landowners would like me coming onto their property to look for my drone with a chainsaw in my hand! Haha.

I got brave one day and decided to make a long distance flight across flat fields and forests. I was quite nervous but went about 1.2 miles the first time before having signal strength issues and returning. A few days later I put parabolic reflectors on the controller and tried again.

I flew at 200 feet altitude to a distance of almost 2 miles (2.8km). I had good LOS, and it was supposed to be a calm evening, wind about 7 mph from the west, on both weather apps I use. I was flying out directly south.

I had no issues on the outward leg, but shortly after I swept around a loop to come back, I started losing signal. The video kept cutting in and out, and I was getting signal warnings. I quickly started to climb assuming some trees might be interfering with the wifi. I only reached 230 feet before getting wind warnings for the first time in the flight, and it was telling me that automatic return to home was not possible.

I couldn’t believe it because it was such a calm evening. I figured out later from looking at the drone attitude on PhantomHelp there was quite a cross wind, a bit north of west – so also a little bit of a headwind on the return leg. I would never have attempted the flight if I had known those were the conditions.

The signal was still cutting in and out as I flew home, but I was afraid to go higher trying to improve it because of the wind. The last thing I wanted was to lose signal and have a fly away at the same time. I was also worried it might try and land where it was which might have meant losing it in the forests. I dared not go higher because of the wind, or lower because of the weak signal. So I kept flying and prayed.

I had climbed to 230 feet, but I lost the signal completely anyway. At some point I got and RTH intiated message, then nothing. My heart rate started to rocket! I kept trying to fly it forward in the hope it was getting my joystick commands, and that it might reconnect when closer. I didn’t know what else to do. I had no video or telemetry.

I thought about closing and reopening the GoFly app, but didn’t think that would help. I was really unsure in my panic as to whether I should initiate RTH, but was afraid it would land where it was because of the wind, and I wouldn’t have the GPS info and never find it. In fact I thought it might be landing at that very moment anyway.

After the longest 30 seconds of my life, and with my heart pounding, the connection suddenly restored. I switched it to Sport mode and flew it home. It took me a while to calm down from that experience.

When I looked at the flight records, the MM had initiated Go Home after the disconnect, in spite of the wind and saying automatic RTH wasn’t available. It actually stopped, re-oriented to point home, and accelerated to Sport Mode speed (didn't know it would do that, but in windy conditions that is really smart!). I had set the RTH to 170 feet so it was already above that. It did exactly what I would have wanted it to do, but didn’t expect.

I’m not sure why it went into Go Home mode when it was giving me the warnings saying automatic RTH wasn’t possible, but happy it did. Maybe RTH was only suspended very briefly with a strong gust?? It came out of the mode for some reason during the return flight and handed control back to me. I’m not sure if that was because I was continuing to provide stick inputs. I didn’t even know it had ever taken control away from me, I was simply attempting to fly it the whole time.

Not sure I fully understand how MM's safety system works, but I'm very impressed. However, next time before a long flight I think I’ll go up to 400 feet briefly and check for wind warnings first.
 
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The signal was still cutting in and out as I flew home, but I was afraid to go higher trying to improve it because of the wind. The last thing I wanted was to lose signal and have a fly away at the same time. I was also worried it might try and land where it was which might have meant losing it in the forests. I dared not go higher because of the wind, or lower because of the weak signal. So I kept flying and prayed.

I thought about closing and reopening the GoFly app, but didn’t think that would help. I was really unsure in my panic as to whether I should initiate RTH, but was afraid it would land where it was because of the wind, and I wouldn’t have the GPS info and never find it. In fact I thought it might be landing at that very moment anyway.

Not sure I fully understand how MM's safety system works, but I'm very impressed. However, next time before a long flight I think I’ll go up to 400 feet briefly and check for wind warnings first.
All that anxiety could be avoided by considering the wind direction and speed before launching.
Think about the flight home ... if the drone would have to fight against a stiff headwind, you are probably flying the wrong direction ?
It actually stopped, re-oriented to point home, and accelerated to Sport Mode speed (didn't know it would do that, but in windy conditions that is really smart!).
I had set the RTH to 170 feet so it was already above that. It did exactly what I would have wanted it to do, but didn’t expect.
If it did, that's not documented anywhere.
I'd be interested to see that data to see what happened.
I’m not sure why it went into Go Home mode when it was giving me the warnings saying automatic RTH wasn’t possible, but happy it did. Maybe RTH was only suspended very briefly with a strong gust?? It came out of the mode for some reason during the return flight and handed control back to me. I’m not sure if that was because I was continuing to provide stick inputs. I didn’t even know it had ever taken control away from me, I was simply attempting to fly it the whole time.
If you post that data, we might be able to work out what was going on.
 
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I flew at 200 feet altitude to a distance of almost 2 miles (2.8km). I had good LOS

I don’t think you fully understand the regulations. It’s not just a matter of having nothing between you and the drone, you have to actually be able to see it. Once it gets past about 500m, I would think that very few people would be able to see something as small as the Mini.
 
I couldn’t believe it because it was such a calm evening.
You learned that at altitude, the wind can be quite a bit different than at the surface or a the local reporting station.

It actually stopped, re-oriented to point home, and accelerated to Sport Mode speed (didn't know it would do that, but in windy conditions that is really smart!).

I too would like to see the data from the flight as we have not seen any documentation the Mini will switch to Sport mode during RTH function.
 
its a better thrill than being in the bookies waiting on a three horse multiplier bet to come in on the last furlong.
RTH is fairly bulletproof long as you have the correct height set and arent trying to return against a gale force wind.
 
You think that's scary. How about waiting 4 minutes from when your P3 lost signal before signal was regained?

In that instance as per comparison of AC and device logs, the RC lost reception of AC, but AC was still receiving from RC. It was hovering much of those 4 minutes waiting for me to tell it what to do next. It returned home only because the battery was getting low. I bet some kayakers/canoers thought I was spying on them.
 
You think that's scary. How about waiting 4 minutes from when your P3 lost signal before signal was regained?

In that instance as per comparison of AC and device logs, the RC lost reception of AC, but AC was still receiving from RC. It was hovering much of those 4 minutes waiting for me to tell it what to do next. It returned home only because the battery was getting low. I bet some kayakers/canoers thought I was spying on them.
I had almost the same experience today , was forrest flying at ground level so had rth set to hover , flew up through a gap in the canopy , and proceed to fly out of range. Lost the connection and the screen went blank. Waited at least 5 mins before I got a RTH notification due to low battery. Legged it back to the home point just as the MA-2 was decending
 
...I had no issues on the outward leg, but shortly after I swept around a loop to come back, I started losing signal. ...
It's the turns that always get me. The legs of the mini contain the antennas. They work best when lined up with the controller.

I have my RTH set at minimum height (for surrounding area) to avoid high winds as much as possible. The problem is the lower the mini goes the more difficult a strong signal becomes.
It's a trade off, but RTH has never failed me yet. My biggest worry is a falcon/hawk taking my mini out on it's way home!
 
You learned that at altitude, the wind can be quite a bit different than at the surface or a the local reporting station.

I too would like to see the data from the flight as we have not seen any documentation the Mini will switch to Sport mode during RTH function.
I knew that, but I was also using the UAV Forecast app which allows you to set altitude for wind data. As I said, to be more confident before a long flight, I will fly to 400 feet first to get some confirmation.

What is the best form to post data?
 
I don’t think you fully understand the regulations. It’s not just a matter of having nothing between you and the drone, you have to actually be able to see it. Once it gets past about 500m, I would think that very few people would be able to see something as small as the Mini.

I do. I was referring to LOS in the context of wifi signal connection strength. As far as vision goes, I am one of the few that you mention. :D
 
RTH never fail unless the drone lose satellite signal. Very low chances that something like that happened outdoors over 100 FT high.
 
RTH never fail unless the drone lose satellite signal. Very low chances that something like that happened outdoors over 100 FT high.

Thanks. Good to know.
What about it changing "RTH" to "Landing" in high winds? Is the "Automatic RTH not available" warning something to be concerned about? I would particularly want to know that it might hover or attempt to land if I'm over water when I lose connection.
 
What is the best form to post data?
Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report of the flight.
Come back and post a link to the report it gives you.
Or .. just post the txt file.
What about it changing "RTH" to "Landing" in high winds?
Is the "Automatic RTH not available" warning something to be concerned about?
I would particularly want to know that it might hover or attempt to land if I'm over water when I lose connection.
The only reason your Mini would go from RTH to Autolanding would because it reached critical low voltage.
Again this is something you can easily avoid by making sure you aren't stuck fighting a stiff headwind to get home.
 
Here are the CSV files. I took out the GPS data for privacy reasons.

Note the flight record was split into two parts as the Mini lost connection and reconnected.
 

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Here are the CSV files.
Interesting, you've uncovered an unknown feature.

Your second file shows you pushing te right stick full forward while the Mini is in RTH.
The pitch angle is up close to 30° and the speed is around 12 metres/sec.
This is what normally happens in Sport Mode and it's not documented in the manual.
Previous models have only allowed max speed with the right stick to be the same as P-GPS (Normal) Mode.
Once you switched to Normal Mode with the stick full forward, the max tilt was 20° and speed was 8 m/s.
When you later switched to Sport Mode, max tilt was 30° and speed was back to 12 m/s.

But if you have no signal, the Mini won't know about your joystick input and max RTH speed would be the usual 8 m/s.
 
It wasn't clear to me when the Mini knew about my stick inputs or not. I kept trying to fly it home in case it did. I'm not sure what brought it out of Go Home mode, other than I was trying to fly it and it reconnected to the RC (I'm unclear how uplink and downlink connections are prioritized).

I didn't switch it to P Mode. It went into P-mode when it came out of Go Home. After flying it a bit after re-connection and still getting wind warnings I switched to Sport Mode.

I had to laugh when I looked at the data, because under stress I was pushing the right stick a bit left of center. I'm surprised I didn't bend the joystick to be honest. :D
 
Come to think of it, I have gotten a message about RTH possibly being affected, but that had to do with RTH potentially crossing geofencing zones. I think that was with my M2 which uses Go, but zone behavior is similar across models. AC won't go into an authorization zone if not locked, and won't go into a restricted zone at all. AC will just sit at the zone border as if it were a physical obstacle.

One poster reported that happening to him with a Mini, though for him the Mini was overcome by wind, lost signal while still overcome by wind, and landed when the wind blew it into an authorization or restriction zone.
 
@Meta4 Pg 14 of the user manual, bullet point 3, states the "speed, altitude and orientation" of the aircraft can be altered during RTH if there is a control signal. It doesn't explicitly confirm that the aircraft can be "pushed" to go faster than default RTH speed, but kind of implies it can. Some other users on here have reported hitting higher speeds than 8m/s using this method.

Handy to know, especially if it's a bit marginal weather.
 
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