Writing this up for my husband who would like some help on working out what went wrong here!  He is a newbie so still learning lots.  So.. a beautiful clear morning - took the new drone for a fly. It had gone out a ways and due to battery levels dropping it was coming home.. using the return to home function. Almost home and the controller starts beeping with a low battery (he hadn't realised it was not sufficiently charged). The drone flies past home and is not responding. Controller loses contact with the drone and eventually goes off. The drone was found at the precise spot where the flight record said it ended up. It had fallen from about 30m. Hit a tree and the battery was a long ways away smashed up but the drone was hardly injured. was able to be easily repaired here in Cambodia where we live.. for a price.
I don't have the flight record uploaded (and can't upload presently as I don't have the device) - i will try to in a few days - so maybe that might help.
We think the problem was the battery on the controller dying but the drone was already on the return home. Shouldn't it already know where home is and come straight there, or can it not do that without the controller?
Thanks for any input!

the main purpose of the return to home feature is for the drone to automaticaly return to its take of point if it looses signal with the controler.
so the battery going flat on the controller would not have caused the drone to over shoot its home point.
the most likely senario that i can think of is that the drone failed to lock onto enough satelites prior to take off to establish a correct or acurate home point.
i think the flight log is the only thing that will be able to solve this little puzzle.
please upload it  and post a link to it here when you can im sure our log gurus will be able to tell you what went wrong and posibly why

OK, so to be clear, was it the battery on your RC that you say was low? You mention early in the post that it was returning home because of low battery levels and then later you mention the RC turning off. Was both the phantom and the RC battery levels low? The phantom is supposed to RTH when is loses signal from the controller, or if it senses it's battery is low. So if that is what is was doing all was as it should be. I guess without the log file we will all be guessing, but did you hear it say the home point was recorded. If all battery levels were low and he just took off, maybe the phantom did not record a "new" home point". Sounds like it may have been trying to return to a point different that where he just took off from. What is not clear is if your RTH height was set high enough or was the phantom trying to land because of low power?  Either way is sounds like it was heading somewhere else right? Some more clarity on these couple issues will help, but the log file is really needed here.

Not to rub "salt in the would" here, but it is very important to make sure both aircraft and controller are fully charged before flight. The controller will hold a charge for much longer time than the phantom, bud normally the only thing that will happen is the aircraft will RTH because of signal loss. But the aircraft is another issue and there are numerous instances where the aircraft can not perform like expected when a partially charged battery was used. Strange things can happen. A hard lesson to learn for sure.

If you have your display device to hand that was used on that flight, tablet or mobile phone, then the flight record can be uploaded to

Here

There are instructions on that web page on where to find, and how to upload the file.

When uploaded you can post a link to the resulting page, and some of the experienced pilots here may be able to explain what happened during that flight.

thanks so much everyone. Yep.. i will upload the log in a few days (or when i can get online with the tablet again). We live in cambodia and our internet connection is not good at home (where the tablet is right now with the log on it) and I just came to town now so i have good internet here. So the phantom battery was fully charged when he took off but when there was 50% i think remaining, the return to home started. That was all normal. It was on its way home and it seems like it kept losing signal and he did a few manual corrections.. and it was very close when it went off track - a couple of hundred metres out of sight - then the controller started beeping from a low battery. He had just charged it but the power connection was not good and it obviously didn't get charged and he didn't check before use (lesson learned!)

Hellsgate Posted at 2018-4-18 04:00
the main purpose of the return to home feature is for the drone to automaticaly return to its take of point if it looses signal with the controler.
so the battery going flat on the controller would not have caused the drone to over shoot its home point.
the most likely senario that i can think of is that the drone failed to lock onto enough satelites prior to take off to establish a correct or acurate home point.

What our friend told me just now (who flies a drone but maybe can get things wrong) was that if the controller loses power then the drone doesn't know what to do.. that is important to know - so .. actually the drone itself should know where home is without the controller? is that right? shall have to look at the sattelite issue.

RicardoGray Posted at 2018-4-18 04:04
OK, so to be clear, was it the battery on your RC that you say was low? You mention early in the post that it was returning home because of low battery levels and then later you mention the RC turning off. Was both the phantom and the RC battery levels low? The phantom is supposed to RTH when is loses signal from the controller, or if it senses it's battery is low. So if that is what is was doing all was as it should be. I guess without the log file we will all be guessing, but did you hear it say the home point was recorded. If all battery levels were low and he just took off, maybe the phantom did not record a "new" home point". Sounds like it may have been trying to return to a point different that where he just took off from. What is not clear is if your RTH height was set high enough or was the phantom trying to land because of low power?  Either way is sounds like it was heading somewhere else right? Some more clarity on these couple issues will help, but the log file is really needed here.

Not to rub "salt in the would" here, but it is very important to make sure both aircraft and controller are fully charged before flight. The controller will hold a charge for much longer time than the phantom, bud normally the only thing that will happen is the aircraft will RTH because of signal loss. But the aircraft is another issue and there are numerous instances where the aircraft can not perform like expected when a partially charged battery was used. Strange things can happen. A hard lesson to learn for sure.

thanks . yep . battery on RC was beeping then went off. power on the drone was normal for a return home .. i think there was still 30% remaining when it actually stopped.
Yep . we are lucky it survived the crash and we can actually learn the lesson to fly another day!!
Yeah.. really need that log uploaded. Will try to do.

Ok this is how it works when you start the drone it will search for and lock onto gps satellites once it has found enough of them it it can then determine its location it uses this location as its home point.
Its important to not take off untill this home point has been set.
If you do take off prior to the home point being set then the craft could set its home point at the location it does get a lock on enough satellites.
If you are in an area with poor gps coverage this can sometimes take a mjnute or 2 before the home point is set now if you happen to take off prior to this and fly around the drone wont know were it is and would most likely be flying useing vps or vision positioning system and barametric readings this is ok if you are indoors but not ideal when outside. You can quite easily fly a long distance in a cple of minutes.
Im not trying to say this is what has happened but it is a possibility.
We will need to see the flight log to determine the exact cause..
The fact that your batteries were low at take off and you were recieving low battery warnings  may have an important part to play in what has happened, but again the flight log will show exactly what happened and possibly why it happened.

betreedcam Posted at 2018-4-18 05:03
thanks . yep . battery on RC was beeping then went off. power on the drone was normal for a return home .. i think there was still 30% remaining when it actually stopped.
Yep . we are lucky it survived the crash and we can actually learn the lesson to fly another day!!
Yeah.. really need that log uploaded. Will try to do.

If you lost connection to the drone prior to the crash then the flight log on your device wont show anything after the power whent out on the rc.
There is a log stored within the drone itself but i believe this can only be retrieved by dji themselves

Sounds to me like the pilot needs to read the manual cover to cover a couple times before he does anything else...

I like to travel and I write a lot of informative essays about it. On https://pro-essay-writer.com/blog/informative-essay-topics you can find info that help you to choose a topic.

Mark The Droner Posted at 2018-4-18 05:22
Sounds to me like the pilot needs to read the manual cover to cover a couple times before he does anything else...

haha!  yes .. he was just a bit rushed and forgot to check that the battery actually charged.. there are always lessons to learn... some harder than others. But here just trying to work out why it didn't come home on its own like we thought it would... or should have.

Hellsgate Posted at 2018-4-18 05:19
If you lost connection to the drone prior to the crash then the flight log on your device wont show anything after the power whent out on the rc.
There is a log stored within the drone itself but i believe this can only be retrieved by dji themselves

what was funny about the flight log was that the point that it stopped on the log was the exact spot to the T where it had fallen (we loaded the coordinates into a garmin gps and went directly to it!  Even though the controller was reading that it had lost signal, low battery etc..  then turned off.  I think I should not worry anyone anymore about this until I can upload the log. Thanks for all your help!

Thanks for reaching us. Please refer the below and export the flight records when you are convenient, we'd like to look into the exact status.

Android: Connect the device to the computer, find the flight records stored in …\DJI\dji.pilot\FlightRecord\, and copy the required flight records to the computer.
iOS: Connect the device to the computer, launch the iTunes, find the flight records in the DJI GO app, and copy the FlightRecord folder to the computer.

http://www.phantomhelp.com/logviewer/862O4ZA93HVD3OU0OEJS/

Friends - finally back from the forest - and here is our flight log.. i hope i have attached the link properly.
Recap: flight was going fine. Did a return to home when the battery indicator of the drone suggested to do so. On the way back, it appeared that there was no movement (and so he..my husband) manually did a few little adjustments.. i think he was a bit worried it wasn't coming at all - whether that over-rid the return to home feature we would like to know. Also at some point the controller started beeping with a low battery and eventually died.. but only right at the end there. Drone was found at exact point on the map here where it landed (crashed in a tree).
Drone has been fixed locally here. Would like to know what we did wrong before we take it up again (apart from the obvious .. keep batteries charged! learned that one!)
THanks for all your help!

The answer may be here:   "It was on its way home and it seems like it kept losing signal and he did a few manual corrections.. "   If he did corrections, he had to cancel RTH first.

ALABAMA Posted at 2018-5-1 06:05
The answer may be here:   "It was on its way home and it seems like it kept losing signal and he did a few manual corrections.. "   If he did corrections, he had to cancel RTH first.

Thanks.. so excuse my ignorance here in asking dumb questions.. so he had engaged RTH.. it didn't look like it was coming back right to him.. so he only just moved the control sticks a bit.. does that automatically disengage the RTH?  Thanks. If yes, than that is our problem.

Just moving the sticks should not cancel RTH.  Pushing The H button again would.

ALABAMA Posted at 2018-5-1 06:24
Just moving the sticks should not cancel RTH.  Pushing The H button again would.

Hmmm.. thanks.. shall investigate more

This is certainly a weird one.  Somebody will have to look at the inputs.  Strange that auto landing would happen and speed continues.  Labroides can probably tell you exactly what happened.

Correct me if I am wrong,   but the log doesn't show a HOME Point Recorded.

I believe auto landing happens after you've reached your 2nd low battery warning......14% would be right there, depending on your settings.  I would suggest, that once you get down to around 40% that you should be in LOS ( Line of Sight )   
Just now looking again at the log.......it appears you started your flight at 94% flight battery...........your cell voltage at the time of auto RTH was lower than the reported 54%.......closer to 40%

Now,  at that point being well over a mile away and 1600ft in altitude.......wow!!  I have stated this in other threads, as well as tested this on my own equipment.......starting with less than 100% battery you can NOT TRUST the percentage of battery.  You NEED to look at the cell voltage.........rule of thumb to be safe ..... be home and landing at 3.75vdc/cell ( TO BE SAFE )   If you are adventurous, get back to within LOS and let the AC fly until it auto lands and check your cell voltage.......this way you don't have to "Try to find it"

I read more...... In this case,  SETTING the Home Point would have solved this issue.  Not having the RC and screen visual,  just plane scary!!  I am very happy you have the AC back and fixed!   Please test the flight battery as stated above so you can feel comfy flying, and know where you're at with your flight battery.  I't ok to fly with a partially charged battery ( over 50% ) but then you MUST watch the cel voltage!

Good luck
Randy

rwynant V1 Posted at 2018-5-1 08:08
Correct me if I am wrong,   but the log doesn't show a HOME Point Recorded.

I believe auto landing happens after you've reached your 2nd low battery warning......14% would be right there, depending on your settings.  I would suggest, that once you get down to around 40% that you should be in LOS ( Line of Sight )   

m 15.5s
P-GPS
12satellites
0ft
1.0ft
0mph
8.7ft
94%
16.928V
4.234V
4.234V
4.231V
4.229V
0.005V
Home Point recorded. Return-to-Home Altitude:30M

ALABAMA Posted at 2018-5-1 08:22
m 15.5s
P-GPS
12satellites

OHH Snap!

I must have blown right by that........once take off,  I started dragging the slide down......

Thank you for the correction.......

So,  in a Mavic thread,   the OP showed a low voltage of 3.6/cell  but a Percentage of 40% battery left......he had a similar experience.....the AC started a left arc and crashed no where near the home point.

I am starting to see a pattern here where cell voltages of less than 3.7 per cell can be dangerous.

OK.. thanks . so perhaps the RTH didn't work quite as well because of the low battery? note to self - watch the battery.. but not just the percent but the cell.  
what would moving the control sticks do (without disengaging the RTH).. nothing?

rwynant V1 Posted at 2018-5-1 08:08
Correct me if I am wrong,   but the log doesn't show a HOME Point Recorded.

I believe auto landing happens after you've reached your 2nd low battery warning......14% would be right there, depending on your settings.  I would suggest, that once you get down to around 40% that you should be in LOS ( Line of Sight )   

thanks for the detailed tip! good for us to note about not relying on the % at all.

Hi, during the Return to Home, there was a lot of braking to avoid obstacles this wastes a lot of power for 1, this in turn reduces the time left on battery, prob best to turn off the forward sensors when sunny, looks to me that it took a different path to circumvent the obstacles (the sun lol) and wasnt able to get back on track due to obstacle (then sun) and it was in landing mode, if it wasnt the sun then it was raining

Something i do not get though, was was it saying critical power ac is landing at 20% thought it did that at 10% unless you had changed it to 20% in the settings?

Moving the sticks would control the ac whislt its still heading home, like it did in this case....

Heres a different perspective

Hellsgate Posted at 2018-4-18 04:00
the main purpose of the return to home feature is for the drone to automaticaly return to its take of point if it looses signal with the controler.
so the battery going flat on the controller would not have caused the drone to over shoot its home point.
the most likely senario that i can think of is that the drone failed to lock onto enough satelites prior to take off to establish a correct or acurate home point.

Your answer seems the best here.  I think it has to be that the home point was not established.  Thanks!

The Home Point was established with 12 satellites! albeit nearly 10ft away....

The home point was not recorded until some time after the aircraft got airborne, it was only seeing 11 satellites for most of its time on the ground. The probable reason for this could be rainforest canopy blocking the view of the satellites. This is why launching from an open area is good practice, and also waiting for the aircraft to get a GPS fix. Once the aircraft it in the air, it sees 17 satellites. But in any event, the aircraft climbed straight away to 1642 feet, the maximum altitude, and who knows what wind strength there was that high up.

Eventually the aircraft loses the signal and it decides the battery is too low, so it heads home, at that altitude. It sensed an obstacle several times, most likely the sun, and this caused it to stop and make changes to its path, and finally when it got where it thought home was, it had to descend from around 1400 feet. During the descent, it looks as if the aircraft was being blown off course by high altitude winds, which the aircraft was trying to fight. I think thisd is why it appeared to go past the home point. Descending took nearly 3 minutes, and at the start of descent the battery was at 24%, but as it got down to the last part of its descent, the battery was at 14%, and the flight record stops there, with the aircraft still 66 feet or 29 feet in the air, depending upon whether you believe the IMU or the VPS system. In the last part of the descent, the winds at the lower altitude may have been a bit calmer and it tries to head back to the correct home point, but eventually the battery gets too low and the motors shut down.

Bashy Posted at 2018-5-1 21:05
Hi, during the Return to Home, there was a lot of braking to avoid obstacles this wastes a lot of power for 1, this in turn reduces the time left on battery, prob best to turn off the forward sensors when sunny, looks to me that it took a different path to circumvent the obstacles (the sun lol) and wasnt able to get back on track due to obstacle (then sun) and it was in landing mode, if it wasnt the sun then it was raining

Something i do not get though, was was it saying critical power ac is landing at 20% thought it did that at 10% unless you had changed it to 20% in the settings?

Thanks for writing that up.  good to learn about the sun being considered and obstacle. It was a beautiful clear morning hence the long and high flight..  Someone else mentioned that the % battery doesn't always work great when a flight started with less than 100% full batteries.. so maybe the 20% at the end was also less than it normally should have read..  not exactly sure what the alarm was set at. thanks!

betreedcam Posted at 2018-5-2 01:29
Thanks for writing that up.  good to learn about the sun being considered and obstacle. It was a beautiful clear morning hence the long and high flight..  Someone else mentioned that the % battery doesn't always work great when a flight started with less than 100% full batteries.. so maybe the 20% at the end was also less than it normally should have read..  not exactly sure what the alarm was set at. thanks!

Please can you check to see if Smart Return to Home is enabled?

• I think that during the RTH it is flying directly into a low sun shortly after sunrise, and it sees that as an obstacle, that is why it wasn't making good progress.
• Eventually it decides that because it is very high (half Km high), it needs to do an early auto landing to avoid running out of battery.  At this point it has not reached home yet, but so far has been flying in a straight line towards home, it does not pass home until the next step:
• During the auto landing, normally it will come straight down, but you can adjust the landing position using the controls, which will work as in normal flight, that is what accounts for all the movement after auto landing starts, essentially it is flown in an arc starting west of the home point and ending the same distance east of the home point, sometimes flying at full speed - with half that distance it could have been successfully landed back home.
  

• So your main mistake was returning home directly into a low sun.
• Second mistake was flying it well out of sight so that you couldn't see what was happening, even if it had been directly overhead, you would have great difficulty seeing or hearing it at half a kilometre up.
• Third mistake was the controls during landing, you should have looked at the map view on the controller and flown the aircraft arrow direct towards the home point marker and stopped directly overhead, or maybe a little to the side just in case it did run out of battery on the half kilometre journey back down and then drop on your heads!  This would have been very easy to do if you had some experience but it looks like you were trying to find your way back using the video image and got lost.
  

ALABAMA Posted at 2018-5-1 06:57
This is certainly a weird one.  Somebody will have to look at the inputs.  Strange that auto landing would happen and speed continues.  Labroides can probably tell you exactly what happened.

It allows you to adjust the landing position during an auto landing, looks like the pilot was trying to find the way home during auto landing using the sticks and the video image instead of the map, and got lost.

Nigel_ Posted at 2018-5-3 03:07
It allows you to adjust the landing position during an auto landing, looks like the pilot was trying to find the way home during auto landing using the sticks and the video image instead of the map and got lost.

Good call, Nigel.  Think you are spot on.

Nigel_ Posted at 2018-5-3 03:07
It allows you to adjust the landing position during an auto landing, looks like the pilot was trying to find the way home during auto landing using the sticks and the video image instead of the map, and got lost.

If I recall,  towards the end of flight, the RC battery went KaPUT....shut off the RC,  so no video or map to look at.......and far enough away, there was no visual.

Just happy to know they got their bird back!!

Randy

rwynant V1 Posted at 2018-5-3 09:02
If I recall,  towards the end of flight, the RC battery went KaPUT....shut off the RC,  so no video or map to look at.......and far enough away, there was no visual.

Just happy to know they got their bird back!!

There was a map available for as long as the log lasts, and the log lasts long enough for the VPS to see the ground 9 meters below, and the landing appears to have been delayed by the pilot attempting to stop it landing in a tree, so I'm fairly sure it could have been safely landed at the home location before the battery ran out.

Very easy to not think of using the map if you are in a panic and don't have experience, that is why beginner mode has distance and height limits that keep the aircraft well within eye sight.

Nigel_ Posted at 2018-5-3 09:39
There was a map available for as long as the log lasts, and the log lasts long enough for the VPS to see the ground 9 meters below, and the landing appears to have been delayed by the pilot attempting to stop it landing in a tree, so I'm fairly sure it could have been safely landed at the home location before the battery ran out.

Very easy to not think of using the map if you are in a panic and don't have experience, that is why beginner mode has distance and height limits that keep the aircraft well within eye sight.

Thank you Nigel,

I certainly need to learn more about the available info in the flight logs.  When I click on the flight log link, all I see is a basic excel sheet of data..........

Please help me see more!!

Thank you,
Randy

rwynant V1 Posted at 2018-5-3 20:17
all I see is a basic excel sheet of data..........

What you see is what you choose to see - why look at the "basic excel sheet" when you could look at the data it contains?

Even the view given on the web page ends with the drone seeing the ground on the VPS column and shows the straight path towards home that goes off course shortly after the Auto Landing message.

If you want to see the control inputs then you need to press the "Download CSV" link and view it in Excel or another spread sheet viewer.  There is also the "Download flight log" link which gives you all the raw data, but I didn't bother with that as in this case everything we need is available in the CSV file.

AH HA.....  I see

Didn't realize there were tabs.  Thank you

Randy

Nigel_ Posted at 2018-5-3 00:51

I think that during the RTH it is flying directly into a low sun shortly after sunrise, and it sees that as an obstacle, that is why it wasn't making good progress.

Eventually it decides that because it is very high (half Km high), it needs to do an early auto landing to avoid running out of battery.  At this point it has not reached home yet, but so far has been flying in a straight line towards home, it does not pass home until the next step:

During the auto landing, normally it will come straight down, but you can adjust the landing position using the controls, which will work as in normal flight, that is what accounts for all the movement after auto landing starts, essentially it is flown in an arc starting west of the home point and ending the same distance east of the home point, sometimes flying at full speed - with half that distance it could have been successfully landed back home.

Thank you for this clear summary of what likely went wrong. really helps us in our learning journey!!