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Drone disconnected and Lost
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6209 41 2019-1-23
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Nando Martins
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Flight distance : 2032900 ft
Brazil
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Hi Guys, let me ask you something. On January 09 I was flying with my Mavic Air and when I was returning to the home point the drone disconnected, the screen of the mobile device turned gray and the drone landed in the sea at 370 meters from the home point and I lost my drone. Do anyone have any comments about this? I appreciated

https://app.airdata.com/share/xlzahg


2019-1-23
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msinger
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Considering the low battery level, it likely auto landed into the water short of the home point due to reaching the critically low battery level. Your flight log doesn't show that part of your flight, so that cannot be confirmed.
2019-1-23
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DJI Gamora
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Hi there, thank you for reaching out and we're sorry to hear about the trouble. With regards to that, I would recommend reaching out one of our support channels in order for you to have the guide on what you'll need to do and have a data analysis to find out what could be the cause. You may just go to this link https://www.dji.com/support. Thank you for your support.
2019-1-23
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Nando Martins
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Brazil
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msinger Posted at 1-23 11:20
Considering the low battery level, it likely auto landed into the water short of the home point due to reaching the critically low battery level. Your flight log doesn't show that part of your flight, so that cannot be confirmed.

the drone was with 30% of charge at 370 mts from home point when it disconnected, so it should have returned to home and did not happen ... auto landing starts with 10% of charge and even so when the drone disconnects it goes back to HOME POINT
2019-1-23
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Nando Martins
lvl.2
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Brazil
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msinger Posted at 1-23 11:20
Considering the low battery level, it likely auto landed into the water short of the home point due to reaching the critically low battery level. Your flight log doesn't show that part of your flight, so that cannot be confirmed.

the drone was with 30% of charge at 370 mts from home point when it disconnected, so it should have returned to home and did not happen ... auto landing starts with 10% of charge and even so when the drone disconnects it goes back to HOME POINT
2019-1-23
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him7403
Second Officer
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Canada
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Nando Martins Posted at 1-23 11:34
the drone was with 30% of charge at 370 mts from home point when it disconnected, so it should have returned to home and did not happen ... auto landing starts with 10% of charge and even so when the drone disconnects it goes back to HOME POINT

Could you post all the log? Why there's no log after 25% battery?
2019-1-23
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Nando Martins
lvl.2
Flight distance : 2032900 ft
Brazil
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him7403 Posted at 1-23 15:34
Could you post all the log? Why there's no log after 25% battery?

the log is complete, the DRONE died in the air, did not return to the starting point, simply appeared AIRCRAFT DISCONECTED and never saw my AIR MAVIC
2019-1-23
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Nando Martins
lvl.2
Flight distance : 2032900 ft
Brazil
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him7403 Posted at 1-23 15:34
Could you post all the log? Why there's no log after 25% battery?

thats the problem. Something happened in between. The mavic air stopped recording (log file) at 30%... that was my last contact
2019-1-23
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Skeeter Honey
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Nando Martins Posted at 1-23 15:52
thats the problem. Something happened in between. The mavic air stopped recording (log file) at 30%... that was my last contact

Did you get cached video on your phone/tablet?
2019-1-23
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Nando Martins
lvl.2
Flight distance : 2032900 ft
Brazil
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Skeeter Honey Posted at 1-23 16:31
Did you get cached video on your phone/tablet?

I take photos, I do not make movies
2019-1-23
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IcannotThinkOfAName
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Flight distance : 623432 ft
United States
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What is interesting is that in the log, the radio signal strength is 100% at the last second.
2019-1-23
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Nando Martins
lvl.2
Flight distance : 2032900 ft
Brazil
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IcannotThinkOfAName Posted at 1-23 16:59
What is interesting is that in the log, the radio signal strength is 100% at the last second.

then he disconnects, the cell phone screen turns gray and I never saw my drone again
2019-1-23
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TheVegeta1974
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try the support link . they might be able to help
2019-1-23
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Nando Martins
lvl.2
Flight distance : 2032900 ft
Brazil
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TheVegeta1974 Posted at 1-23 17:09
try the support link . they might be able to help

I'm already trying, but they are saying that there is no abnormality in the flight record. But every pilot who sees the record realizes that he has akgo wrong, that the drone died or in Brazil has a new triangle of shorts. I'm very disappointed with DJI
2019-1-23
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TheVegeta1974
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Nando Martins Posted at 1-23 17:13
I'm already trying, but they are saying that there is no abnormality in the flight record. But every pilot who sees the record realizes that he has akgo wrong, that the drone died or in Brazil has a new triangle of shorts. I'm very disappointed with DJI

What was your altitude when it lost signal
2019-1-23
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Skeeter Honey
Second Officer
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Nando Martins Posted at 1-23 16:33
I take photos, I do not make movies

That sucks, man.  Gonna make it nearly impossible to find it from diving.
2019-1-23
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Nando Martins
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Flight distance : 2032900 ft
Brazil
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Skeeter Honey Posted at 1-23 17:16
That sucks, man.  Gonna make it nearly impossible to find it from diving.

drug is being the support of the DJI that says that there is nothing wrong with the flight record
2019-1-23
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Nando Martins
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TheVegeta1974 Posted at 1-23 17:15
What was your altitude when it lost signal

40 meters of altitude
2019-1-23
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msinger
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Nando Martins Posted at 1-23 17:13
I'm already trying, but they are saying that there is no abnormality in the flight record. But every pilot who sees the record realizes that he has akgo wrong, that the drone died or in Brazil has a new triangle of shorts. I'm very disappointed with DJI

At the last point in the flight log, the Mavic was flying at an altitude of 66 meters, was 370 meters from the home point, and had 25% battery remaining.

Here are some of the most likely possibilities for your loss:

- Your Mavic attempted to return home and auto landed due to a critically low battery. At the end of your flight log, the critically low battery was going to be triggered at 12% battery. Since your Mavic was flying into the wind on the way back home, that percentage could have increased if the Mavic hit a gust of wind and had to work harder. Assuming the wind remained the same, the data shows your Mavic should have just barely made it home or have at least been close enough for you to visually see it land in the water.

- The battery could have partially or fully dislodged causing the Mavic to power off mid-flight.

- A prop could have been lost mid-flight causing your Mavic to drop like a rock into the water.

- Some kind of defect caused the Mavic to power off mid-flight.

Unfortunately, your flight log doesn't contain information that points to any of the above possible outcomes. So, DJI Support is right on the money when they are saying there is no abnormality in the flight record. If every other pilot realizes something is wrong with your flight record, then those pilots likely don't understand how to read flight logs.

We get it. Nobody likes to lose a drone. However, you decided to fly beyond VLOS (against the law in Brazil, right?) and now want to blame someone else for a fault that cannot be explained.

Any chance you can hire a diver to attempt to retrieve your Mavic from the last known location?

2019-1-23
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Skeeter Honey
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msinger Posted at 1-23 18:29
At the last point in the flight log, the Mavic was flying at an altitude of 66 meters, was 370 meters from the home point, and had 25% battery remaining.

Here are some of the most likely possibilities for your loss:

At 66 meters the wind is much stronger.  I think your first theory is right.
2019-1-23
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Skeeter Honey
Second Officer
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United States
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Although 1200 feet away could conceivably be within VLOS.
2019-1-23
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Nando Martins
lvl.2
Flight distance : 2032900 ft
Brazil
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Skeeter Honey Posted at 1-23 19:09
Although 1200 feet away could conceivably be within VLOS.

30% battery, 370 mts from the starting point, the drone disconnected, had enough battery to reach the starting point, ie the DJI drones are not as reliable as the factory says, and they do not give me an answer of who was wrong and do not assume the technical fault
2019-1-23
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JJBspark
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Nando Martins Posted at 1-23 22:54
30% battery, 370 mts from the starting point, the drone disconnected, had enough battery to reach the starting point, ie the DJI drones are not as reliable as the factory says, and they do not give me an answer of who was wrong and do not assume the technical fault

Hi Nando,

I made a simply calculation for your last part of the flight, wich was a straight line almost pointing towards home.
In P-GPS with 100% stick fwd pitch with an average of 14 degrees pitch-down, so head-wind vector not the problem, problem became the disconnect at 25% batt level at your distance out!
Batt % - Distance (meter) - Speed  (m/s) - Time to reach HP+land

With no disconnection
30 - 664 - 5.4 - 137 [next 5% batt in 50 seconds ]
25 - 383 - 6.2 - 100 [next 5% batt in 50 seconds ]
20 - 102 - 6.2 -  63
18 - at home!

What happens at a full disconnect > at your 25% batt level > MA start a RTH procedure, retrace its route for 60 seconds (yellow to approx. orange marking) , so its flying away from HP!
In the manual is written that after 60 seconds with still no connection the MA fly s back home from that point in a straight line. (so its futher away from HP!)

RTH at that new distance out, HP not to be reached anymore.
Critical power about 12% for an autolanding, IMO this happend you your MA. [10% critical autoland value only true when calulated time to land  in seconds < current height / descending speed in seconds ]


What we all don`t like is a disconnect to our great DJI drones, but we have to take this into account and fly such a flight that when it happens it does not become catastrophic.
Not to be rude but flying above sea with less than 30% at distance far from HP is never a good idea.

cheers
JJB




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2019-1-24
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nixuspix
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When i encounter rarely such disconnections with grey screen, i always restart the RC and connection is back and always i found that the AC was in returning home process.
2019-1-24
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Nando Martins
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Brazil
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JJBspark Posted at 1-24 00:41
Hi Nando,

I made a simply calculation for your last part of the flight, wich was a straight line almost pointing towards home.

Hi, jjBspark

It was like the drone had died in the sky.
In the log it does not register it landing, it says 25% of battery and landing and ends the log.
Funny that DJI says it has no log abnormalities.
And you do not explain the reason for what happened.

And you think it was my fault?
2019-1-24
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msinger
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Nando Martins Posted at 1-24 03:58
Funny that DJI says it has no log abnormalities

Can you specifically point out the abnormalities in your flight log? As far as I can tell, all looks normal and it just abruptly cuts off.
2019-1-24
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JJBspark
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Nando Martins Posted at 1-24 03:58
Hi, jjBspark

It was like the drone had died in the sky.

Hi Nando,

I do not know why there was a disconnected, it happens sometimes.

Was it your fault? well, if it stayed connected it think  your MA returned home at the last batt power.
It is a risk to fly above water with little battery power left at the end....
Last record written in the file is at P-GPS mode, not landing.

So your fault?, nope but guess you are not fully aware what can happen. I would aim to fly at 30% above land, not above water.

cheers
JJB


2019-1-24
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M4VERICK8
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Brazil
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JJBspark Posted at 1-24 00:41
Hi Nando,

I made a simply calculation for your last part of the flight, wich was a straight line almost pointing towards home.

great explanation. thank you JJBspark. Living and learning with u.
2019-1-24
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Eclair29
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JJBspark Posted at 1-24 00:41
Hi Nando,

I made a simply calculation for your last part of the flight, wich was a straight line almost pointing towards home.

Hmm, If RTH is already triggered (manually or because of low battery) and the connexion is lost does the MA really starts to retrace back?? I think it just continues on course.
To be tested.
I also had a case when I lost contact with my MA although it was only 10 meters away in perfect line of sight. I was never able to regain connexion. And because it was "close to home point" the MA decided to land right away.... in the water. The next day a diver was able to get it back for me ($70).
DJI concluded there was no pilot error and the drone is being replaced. But that was because I had reovered the drone and all the internal log files. Otherwise I guess it would have been my loss by lack of proof.
2019-1-24
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JJBspark
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Eclair29 Posted at 1-24 20:15
Hmm, If RTH is already triggered (manually or because of low battery) and the connexion is lost does the MA really starts to retrace back?? I think it just continues on course.
To be tested.
I also had a case when I lost contact with my MA although it was only 10 meters away in perfect line of sight. I was never able to regain connexion. And because it was "close to home point" the MA decided to land right away.... in the water. The next day a diver was able to get it back for me ($70).

Hi,

When the user engaged RTH or the SmartBattery than it will RTH to home. (not in your flight)
When the connection is lost it will retrace its route. (in your flight)

In your flight no RTH was started, that`s why it started to fly its route back for 60 seconds  3 seconds afterthe disconnect.

Best advice i can give (and i live in a country with lots of water) ; if possible always takeoff from a position > 20 meters away from water! Just in case a disconnect happens close to home above water....

cheers
JJB
2019-1-24
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Kirby Harrison 3
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Same thing happened to my spark. Diconected screen greyed out and never came home. I was flying over the countryside way above all tree. And dji put it down as pilot error they do this all the time to save them having to replace the drone.  Dont waste your time with dji!!!
2019-1-25
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Kirby Harrison 3
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Nando Martins Posted at 1-23 17:13
I'm already trying, but they are saying that there is no abnormality in the flight record. But every pilot who sees the record realizes that he has akgo wrong, that the drone died or in Brazil has a new triangle of shorts. I'm very disappointed with DJI

Hi yes thats pretty much what they said to me dji dont care !!!
2019-1-25
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AlphaFlightNW
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Given the recorded battery reading 1, it looks like you took off when the battery was not 100%. Personally, I think a cell blew or that it RTH'd by following the bread crumb trail. Sorry for your loss.
2019-1-26
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Nando Martins
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Brazil
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msinger Posted at 1-24 05:44
Can you specifically point out the abnormalities in your flight log? As far as I can tell, all looks normal and it just abruptly cuts off.


Where did the drone land? Where is the battery discharging? Where does the drone disconnect? Where do you show lowering the altitude? If this is not an abnormality for a flight record, I wanted to know what it is ...
2019-1-28
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elberti
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Good call @JJBspark and sorry to @Nando Martins

@DJI should consider this case and raise a development request => If signal is Lost, then RTH should be activated in the shortest vector (no retrace, no 60 secs, no hovering).


2019-1-28
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Nando Martins
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elberti Posted at 1-28 08:12
Good call @JJBspark and sorry to @Nando Martins

@DJI should consider this case and raise a development request => If signal is Lost, then RTH should be activated in the shortest vector (no retrace, no 60 secs, no hovering).

Thanks for the answer.

@elberti, you noticed that there is something abnormal in the log so I'm waiting for the DJI to pronounce on my case, because note that in the log does not register the aircraft losing altitude, does not show the aircraft disconecting, does not show the aircraft in RTH, not shows the battery level decreasing, it stops us 30% and was flying in P-GPS mode,
2019-1-28
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Adam_Kuzniar
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elberti Posted at 1-28 08:12
Good call @JJBspark and sorry to @Nando Martins

@DJI should consider this case and raise a development request => If signal is Lost, then RTH should be activated in the shortest vector (no retrace, no 60 secs, no hovering).

That doesn't make sense. If I lose a signal, I don't want it to rush back home, possibly colliding with something on its way there, risking even more damage and possibly damaging someone/something else. Retrace is the most logical thing to do (drone thinks if I was there and I signal then if I go back I'll get the signal back).

I had a situation where I started from the middle of the forest  where there was a small opening in the tree canopy and as I was flying I lost the video feed to my phone and I had to restart the RC to get it back. If I did that and drone started making it's way back home, it would surely crash into trees - the GPS & sensors aren't accurate enough to avoid it. Instead it started retracing (which was a safe route because I've already flown it) and I had the time to restart my RC and get the control back.

This is the most logical thing for the drone to do.

Nando Martins Posted at 1-28 08:31
Thanks for the answer.

@elberti, you noticed that there is something abnormal in the log so I'm waiting for the DJI to pronounce on my case, because note that in the log does not register the aircraft losing altitude, does not show the aircraft disconecting, does not show the aircraft in RTH, not shows the battery level decreasing, it stops us 30% and was flying in P-GPS mode,

How would the drone send you the log of disconnection and everything that happened afterwards if it didn't connect back before crashing?
2019-1-29
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Nando Martins
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Brazil
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Adam_Kuzniar Posted at 1-29 04:02
That doesn't make sense. If I lose a signal, I don't want it to rush back home, possibly colliding with something on its way there, risking even more damage and possibly damaging someone/something else. Retrace is the most logical thing to do (drone thinks if I was there and I signal then if I go back I'll get the signal back).

I had a situation where I started from the middle of the forest  where there was a small opening in the tree canopy and as I was flying I lost the video feed to my phone and I had to restart the RC to get it back. If I did that and drone started making it's way back home, it would surely crash into trees - the GPS & sensors aren't accurate enough to avoid it. Instead it started retracing (which was a safe route because I've already flown it) and I had the time to restart my RC and get the control back.

he did not crash, he simply landed without returning to the RTH.
2019-1-29
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elberti
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Adam_Kuzniar Posted at 1-29 04:02
That doesn't make sense. If I lose a signal, I don't want it to rush back home, possibly colliding with something on its way there, risking even more damage and possibly damaging someone/something else. Retrace is the most logical thing to do (drone thinks if I was there and I signal then if I go back I'll get the signal back).

I had a situation where I started from the middle of the forest  where there was a small opening in the tree canopy and as I was flying I lost the video feed to my phone and I had to restart the RC to get it back. If I did that and drone started making it's way back home, it would surely crash into trees - the GPS & sensors aren't accurate enough to avoid it. Instead it started retracing (which was a safe route because I've already flown it) and I had the time to restart my RC and get the control back.

Adam, this was your case with good arguments.
Still, commenting Nando's case, things would be different if the drone went straight home.

After all, would be perfect to have the option to chose what to do after the signal is lost: retrace or RTH.
2019-1-29
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twilight
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The starting point is at 58% battery. That level is from what i know the percentage of storage mode. The battery is putting it self in storage mode, discharging itself to 59 percent. I don't think it's a good point to start a flight. Those intelligent batteries are not that intelligent after all.

I once had a phantom, that on the second flight, i hadnt had the time to wait for the battery to fully charge (it was 4 leds already but not finished). At about 10% battery, it felt from the sky.
https://app.airdata.com/flight/7 ... ENERALNotifications

Since then, i discharge the batteries after a long no fly time, hovering the aircraft in place. Then i fully charge the batteries.

I am sorry for your mavic loss
2019-1-30
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