not that I was planning for this to happen, but I knew there was always possibility.
this is the view from my launch point

I made 3 flights today :
1. everything normal and good
2. mostly fine, except when coming home Solo started to behave strangely (swinging in all directions) and descended on its own, I was unable to hold nor increase the altitude. This minor incident happened in front of me (about 40m out), Solo landed softly in the bushes so I just went to pick it up and bring it back to my launch point
3. this is when I lost the Solo, all started as normal, basically I just wanted to check whether Solo is fine after flight no.2, it launched fine and was holding altitude fine and responding fine to all commands, I flew forward and 35 seconds later it was gone.
I'll describe the last flight no.3 :
I've been to this location 5-6 times in last couple of weeks and always had a good flight.
Observed wind speed from the nearest weather station at the time of my incident was 7km/h (4.3M/h) with gusts up to 15km/h (9.3M/h), I didn't actually notice any wind, it was fairly calm late afternoon.
One thing that was different to all of my previous visits and flights at this location that today for the first time I was descending below the altitude of the launch point. The beach on the photo is about 100m below me, I lost the Solo about 1/3 of the distance between me and the beach.
Last known Solo location (from controller Tlogs) is here :
Google Maps
The launch point was +/- 120m North (more or less) of Solo last known location.
About 30 seconds into this flight (heading towards the beach and descending) Solo started to behave strangely, it was swinging in all directions, I released the right stick and tried to increase altitude with left stick, Solo was not responding and started to have trouble holding altitude, when I noticed that it started to descend on its own, I pressed the Return Home button, it kept on descending, all this time it was swinging/shaking left/right/front/back.
It seemed to be descending straight down, wasn't flying in any direction, just swinging around but descending in straight line. It all happened very quickly, there was not time to do anything else - I tried to increase altitude with left stick for about 3 seconds but when I noticed Solo started to descend, another 1 second later I hit the return home button, 3 seconds later I lost the sight of Solo (it descended behind cliff) and lost signal almost instantly. I was in Fly mode.
I walked towards the beach as far as I could, but there are some cliffs that I couldn't descend. I didn't know it then but after I got home and downloaded Tlogs, I know now that I walked to a distance of about 40m from Solo but I could not recover the signal. Either the battery got dislodged or simply the fact that it seems Solo landed/crashed behind/below yet another cliff that was in the way of signal.
At the time I hit the Return Home, the relative altitude was -20m, but the real GPS altitude was +90m, I lost the signal 3 seconds later, at that time GPS altitude was 54m.
Does anyone know what does GPS altitude mean, is this altitude above see level or is this altitude above ground in that specific location ? My estimate is that the location shown on map as last known location is about 15-20m above see level and I'm trying to determine what was the vertical distance between Solo and ground when I lost the signal.
I know that in those 3 seconds between RTL and loss of signal Solo descended by 36m and it shifted only by 2m SW (heading), I don't know what happened afterwards but I'm assuming it was descending at same rate and if at the time of loss of signal it was only 30m above ground then I expect to find it perhaps only another 2m SW (if not exactly at the same GPS point as last known location).
Battery level was 41% when I lost the signal, is there any chance that battery would not go flat until tomorrow morning (12-14 hours after flight), that would allow me to reconnect the controller as I get closer and find on the map the exact location.
That location is difficult to access and finding Solo among those trees or bushes may be quite difficult, trying to narrow my search area, if my search radius was 50m then I think I may never find it, 20m radius would still be quite hard, 10m radius is doable.
I'm saying this only because when the minor incident happened in flight no.2 and I could see exactly where Solo landed 40m in front of me, I was still having impossibly hard time locating it when I actually walked there, with that flight however I never lost the signal so I was able to pin-point the Solo on the map and believe me I could not see it standing just 2m away (it was hidden in the bush).
The problem is when you lose signal as happened in flight no.3 then you cannot use the map and there is no way to retrieve location information. I had to drive back home (30 minutes away) and another 30 minutes later I analyzed those logs. This is why I suggested to 3DR several times to make this information available in Solo App (last known latitude, longitude, altitude), it can't be that hard to implement, there shouldn't be any need loading log files from controller by Solo App, the app works with this information live during any flight so all they need to do is to keep last known data available to display in the app. If I knew the exact last known location while I was still there, I would've made an effort to find it (it was still 1 hour before it got dark).
here is the flight path (ignore the line on the right, that's the actual point where Solo landed on flight no.2 and my path walking with Solo in my hand back to the launch point, it wasn't actually flying there, I just left the battery on), the actual flight path of the flight no.3 is the line on the left :

some data from the logs :

I actually don't know what happened but the above screenshot shows the violent roll & pitch data when the Solo started swinging around.
If anyone wants to dig in the Tlog for this flight, it's attached as well, just keep in mind the actual flight starts at 6:30, all the data before that is when the Solo landed after flight no.2 and my path walking with it back to launch point.
If you find something that I missed or anything wrong with my assumption where/how the Solo was descending between RTL and loss of signal and my assumption that it should be within very narrow radius of the last known location, please let me know.
There were reports in the past by others who lost Solo same way - when descending below the altitude of launch point, I don't know if that is in anyway related, either way I'm submitting logs to 3DR as well.
Weather forecast for tomorrow is 70% chance of rain, bloody hell.
this is the view from my launch point

I made 3 flights today :
1. everything normal and good
2. mostly fine, except when coming home Solo started to behave strangely (swinging in all directions) and descended on its own, I was unable to hold nor increase the altitude. This minor incident happened in front of me (about 40m out), Solo landed softly in the bushes so I just went to pick it up and bring it back to my launch point
3. this is when I lost the Solo, all started as normal, basically I just wanted to check whether Solo is fine after flight no.2, it launched fine and was holding altitude fine and responding fine to all commands, I flew forward and 35 seconds later it was gone.
I'll describe the last flight no.3 :
I've been to this location 5-6 times in last couple of weeks and always had a good flight.
Observed wind speed from the nearest weather station at the time of my incident was 7km/h (4.3M/h) with gusts up to 15km/h (9.3M/h), I didn't actually notice any wind, it was fairly calm late afternoon.
One thing that was different to all of my previous visits and flights at this location that today for the first time I was descending below the altitude of the launch point. The beach on the photo is about 100m below me, I lost the Solo about 1/3 of the distance between me and the beach.
Last known Solo location (from controller Tlogs) is here :
Google Maps
The launch point was +/- 120m North (more or less) of Solo last known location.
About 30 seconds into this flight (heading towards the beach and descending) Solo started to behave strangely, it was swinging in all directions, I released the right stick and tried to increase altitude with left stick, Solo was not responding and started to have trouble holding altitude, when I noticed that it started to descend on its own, I pressed the Return Home button, it kept on descending, all this time it was swinging/shaking left/right/front/back.
It seemed to be descending straight down, wasn't flying in any direction, just swinging around but descending in straight line. It all happened very quickly, there was not time to do anything else - I tried to increase altitude with left stick for about 3 seconds but when I noticed Solo started to descend, another 1 second later I hit the return home button, 3 seconds later I lost the sight of Solo (it descended behind cliff) and lost signal almost instantly. I was in Fly mode.
I walked towards the beach as far as I could, but there are some cliffs that I couldn't descend. I didn't know it then but after I got home and downloaded Tlogs, I know now that I walked to a distance of about 40m from Solo but I could not recover the signal. Either the battery got dislodged or simply the fact that it seems Solo landed/crashed behind/below yet another cliff that was in the way of signal.
At the time I hit the Return Home, the relative altitude was -20m, but the real GPS altitude was +90m, I lost the signal 3 seconds later, at that time GPS altitude was 54m.
Does anyone know what does GPS altitude mean, is this altitude above see level or is this altitude above ground in that specific location ? My estimate is that the location shown on map as last known location is about 15-20m above see level and I'm trying to determine what was the vertical distance between Solo and ground when I lost the signal.
I know that in those 3 seconds between RTL and loss of signal Solo descended by 36m and it shifted only by 2m SW (heading), I don't know what happened afterwards but I'm assuming it was descending at same rate and if at the time of loss of signal it was only 30m above ground then I expect to find it perhaps only another 2m SW (if not exactly at the same GPS point as last known location).
Battery level was 41% when I lost the signal, is there any chance that battery would not go flat until tomorrow morning (12-14 hours after flight), that would allow me to reconnect the controller as I get closer and find on the map the exact location.
That location is difficult to access and finding Solo among those trees or bushes may be quite difficult, trying to narrow my search area, if my search radius was 50m then I think I may never find it, 20m radius would still be quite hard, 10m radius is doable.
I'm saying this only because when the minor incident happened in flight no.2 and I could see exactly where Solo landed 40m in front of me, I was still having impossibly hard time locating it when I actually walked there, with that flight however I never lost the signal so I was able to pin-point the Solo on the map and believe me I could not see it standing just 2m away (it was hidden in the bush).
The problem is when you lose signal as happened in flight no.3 then you cannot use the map and there is no way to retrieve location information. I had to drive back home (30 minutes away) and another 30 minutes later I analyzed those logs. This is why I suggested to 3DR several times to make this information available in Solo App (last known latitude, longitude, altitude), it can't be that hard to implement, there shouldn't be any need loading log files from controller by Solo App, the app works with this information live during any flight so all they need to do is to keep last known data available to display in the app. If I knew the exact last known location while I was still there, I would've made an effort to find it (it was still 1 hour before it got dark).
here is the flight path (ignore the line on the right, that's the actual point where Solo landed on flight no.2 and my path walking with Solo in my hand back to the launch point, it wasn't actually flying there, I just left the battery on), the actual flight path of the flight no.3 is the line on the left :


some data from the logs :

I actually don't know what happened but the above screenshot shows the violent roll & pitch data when the Solo started swinging around.
If anyone wants to dig in the Tlog for this flight, it's attached as well, just keep in mind the actual flight starts at 6:30, all the data before that is when the Solo landed after flight no.2 and my path walking with it back to launch point.
If you find something that I missed or anything wrong with my assumption where/how the Solo was descending between RTL and loss of signal and my assumption that it should be within very narrow radius of the last known location, please let me know.
There were reports in the past by others who lost Solo same way - when descending below the altitude of launch point, I don't know if that is in anyway related, either way I'm submitting logs to 3DR as well.
Weather forecast for tomorrow is 70% chance of rain, bloody hell.