Phantom 4 Pro crashed - don't understand why

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Hi, I'm new in the forum and would be very grateful for some analysis of what happened to me yesterday.

I was flying my two weeks old Phantom 4 Pro in New Zealand and it crashed into the ocean :( I'm trying to understand why.

I was flying towards a rock which was not too far from the beach. I used the home lock mode to be able to turn the camera freely while keeping one direction. When coming closer to the rock the drone startet drifting to the right (from my point of view), the camera being faced towards me. I countered the drift by moving the right stick to the left and to my surprise I see that the drone is flying more to the right. I was under the impression that around the rock there must be strong winds that the app doesn't show yet and pulled the right stick back, to fly back towards the home point, but instead it is crashing into the rock a few seconds later. More exactly it flies into a cave that I wanted to film into (not fly into). No obstacle avoidance happening.

I was devastated. A guy with a surfboard was so nice to check the area a few minutes after but couldn't find the drone anymore, probably the current took it.

Now I checked the log file and it seems that the P4P all of a sudden switched into ATTI mode, meaning basically when I pulled the stick back it was flying backwards regarding the direction it was facing, so further away from me. I really don't understand why ATTI GOT activated. The rock was not overhanging and not even vertical, so there was clear sky above it. Also the obstacle avoidance did not fire before the first counter move I described above, so I wasn't very close yet to the wall either. I was also not at the spot where the cave is.

When ATTI mode was switched on I still had 9 satellites. As far as I know 4 are enough to get a location.

Could this be a bug? I definitely didn't touch the mode switch. I am still a bit in shock, was really looking forward to use this for a long time :/

I would be very thankful for any help to understand what happened.

Here is the log file:
Phantom Log Viewer - PhantomHelp.com

Thanks already!!
Alex

PS: I'm not a English native speaker, if something is unclear please ask me and I try to explain it better.
 
Last edited:
Hi Kadal, sorry you crashed. If the camera was facing you then you were flying "nose in". In this situation to counter a drift to the right you should have moved the stick to the right. Control inputs are reversed when flying nose in. Some time on an rc simulator is great for building up your piloting skills or buy a cheap quad and fly it like you stole it....
 
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Hi Navarre, I know, but the orientation of the camera doesn't matter in home lock mode. So my question is why it changed to Atti with no reason. In this mode what you say is correct of course, that caused the crash.

Sent from my BLL-L22 using PhantomPilots mobile app
 
Looking at your data suggests that you were losing satellite connection and eventually down to zero at one point. It should have stated 'atti mode' at some point enabling you to salvage it. Not sure if you were flying in a shaded /obstructed area that would basically block your satellite coverage. My P4 routinely does in the area where I live when I am landing due to the forest canopy, it switches over but I am expecting it each time.
 
Hi, I'm new in the forum and would be very grateful for some analysis of what happened to me yesterday.

I was flying my two weeks old Phantom 4 Pro in New Zealand and it crashed into the ocean :( I'm trying to understand why.

I was flying towards a rock which was not too far from the beach. I used the home lock mode to be able to turn the camera freely while keeping one direction. When coming closer to the rock the drone startet drifting to the right (from my point of view), the camera being faced towards me. I countered the drift by moving the right stick to the left and to my surprise I see that the drone is flying more to the right. I was under the impression that around the rock there must be strong winds that the app doesn't show yet and pulled the right stick back, to fly back towards the home point, but instead it is crashing into the rock a few seconds later. More exactly it flies into a cave that I wanted to film into (not fly into). No obstacle avoidance happening.

I was devastated. A guy with a surfboard was so nice to check the area a few minutes after but couldn't find the drone anymore, probably the current took it.

Now I checked the log file and it seems that the P4P all of a sudden switched into ATTI mode, meaning basically when I pulled the stick back it was flying backwards regarding the direction it was facing, so further away from me. I really don't understand why ATTI GOT activated. The rock was not overhanging and not even vertical, so there was clear sky above it. Also the obstacle avoidance did not fire before the first counter move I described above, so I wasn't very close yet to the wall either. I was also not at the spot where the cave is.

When ATTI mode was switched on I still had 9 satellites. As far as I know 4 are enough to get a location.

Could this be a bug? I definitely didn't touch the mode switch. I am still a bit in shock, was really looking forward to use this for a long time :/

I would be very thankful for any help to understand what happened.

Here is the log file:
Phantom Log Viewer - PhantomHelp.com

Thanks already!!
Alex

PS: I'm not a English native speaker, if something is unclear please ask me and I try to explain it better.
Which phone were you using?
 
I used a Huawei Gr5 2017.

There was nothing obscuring the sky or anything. The drop to zero satellites is because by not knowing that I fly Atti, I was making directing the drone into the cave. Why does it switch to Atti when there are 9 satellites available?

Sent from my BLL-L22 using PhantomPilots mobile app
 
There was nothing obscuring the sky or anything. The drop to zero satellites is because by not knowing that I fly Atti, I was making directing the drone into the cave. Why does it switch to Atti when there are 9 satellites available?
In Google Earth it looks like you flew to the bottom of a 100 ft high rock.
Your altitude was just above sea level.
The rocky island would have blocked a lot of the sky and reduced the number of satellites your Phantom could see.
Your satellite numbers dropped from 15 to nine which is why your Phantom went into atti mode.
This would have lost its position holding and it could then drift with the wind.
The satellite numbers dropped lower as your Phantom got closer in and lost even more of its sky view.
This is the most likely explanation I can see.
When ATTI mode was switched on I still had 9 satellites. As far as I know 4 are enough to get a location.
Not with the Phantom. It needs to have a minimum of either 6 GPS sats or 6 Glonass sats
Three GPS + 3 Glonass is not enough.
I was devastated. A guy with a surfboard was so nice to check the area a few minutes after but couldn't find the drone anymore, probably the current took it.
The Phantom would have sunk like a stone when it hit the water.

You could try contacting DJI to see if they think it may have been a failure of the GPS unit.
Upload your flight record from the app - click in the cloud icon.
Then go to DJI online help and tell them the story.
 
I used a Huawei Gr5 2017.

There was nothing obscuring the sky or anything. The drop to zero satellites is because by not knowing that I fly Atti, I was making directing the drone into the cave. Why does it switch to Atti when there are 9 satellites available?

Sent from my BLL-L22 using PhantomPilots mobile app
If there was nothing obscuring it, I have no idea, although mine drops into atti mode and warns me if it falls below 8 satellites and I was under the impression that you needed either 4 or 6 for the drone to fly with full GPS control.
 
I was under the impression that you needed either 4 or 6 for the drone to fly with full GPS control.
With a handheld GPS (no Glonass) unit you need a minimum of 4 sats to get a fix.
With the old P2 series that only used US GPS satellites, the Phantom needed 6 sats before it would in P-GPS mode.
DJI never explained this but it's most likely a safety factor to guard against a poor fix from a bad spread of sats that could be possible with only 4.
But the Phantom using GPS + Glonass sats needs to have a minimum of 6 of one sat type - not a total of 6.
3 GPS + 3 Glonass sats = no fix.
 
With a handheld GPS (no Glonass) unit you need a minimum of 4 sats to get a fix.
With the old P2 series that only used US GPS satellites, the Phantom needed 6 sats before it would in P-GPS mode.
DJI never explained this but it's most likely a safety factor to guard against a poor fix from a bad spread of sats that could be possible with only 4.
But the Phantom using GPS + Glonass sats needs to have a minimum of 6 of one sat type - not a total of 6.
3 GPS + 3 Glonass sats = no fix.
Ah I see, I thought it was a total of six as a combination of both systems. Once I clear the forest floor it jumps straight to 15 or greater satellites and it's all good. Thanks for teaching me something on this cloudy Sunday morning.
 
Ok, thanks for the feedback, helps me to clear my head a bit. But how e do I upload the log in the cloud to show it to the DJI support? I run the DJI Go 4 app and inside the app above the flight logs is no icon.
1485652076423.png
1485652085336.png


Did not find it on Google.

Sent from my BLL-L22 using PhantomPilots mobile app
 
What irritates me also is that after switching to Atti there are a lot of "GPS Position NoMatch" errors. So even when having 11 satellites again (row 1961, 3m 23.9s) it stays in Atti mode, although of one satellite type there would have been 6 then in any case. It shows the NoMatch error there and at 35 other records.

Sent from my BLL-L22 using PhantomPilots mobile app
 
Ok, thanks for the feedback, helps me to clear my head a bit. But how e do I upload the log in the cloud to show it to the DJI support? I run the DJI Go 4 app and inside the app above the flight logs is no icon
On the front page of the app, click the icon above the word Disconnected
Screenshot_20170129-120045-M.png


That takes you to your Flight Records where you select the record and click the cloud icon in the top right corner
Screenshot_20170129-120216a-M.png


What irritates me also is that after switching to Atti there are a lot of "GPS Position NoMatch" errors. So even when having 11 satellites again (row 1961, 3m 23.9s) it stays in Atti mode, although of one satellite type there would have been 6 then in any case. It shows the NoMatch error there and at 35 other records.
The NoMatch messages are new and what they mean isn't clear.
Examining flight records has shown that GPS was accurate even where these messages were popping up.
It seems to be a false alarm like the high wind warning.
 
Hi

I was flying my P4P weeks ago, after 1100meters away from hp i lost the signal to the remote, i went into my car and drove like 150meters away from him where he was on the way to hp, the P4P asked do you want to land - and i pressed no so he followed the route back to ho. But when he had like 800meters left he lost gps signal - remote signal and came up with some compass error. The wind was blowing from the east so he hoowered for 26 minutes (if my canculate) is right to the west so he could be somwhere between 1-4kilometers away from the homepoint. Ive spent many hours walking and flying my friend drone trying to find him but with no luck i lost my brand new P4P.

Was it my fault ? NO cause when you loose the connection and he looses the gps signal or compass the wind takes the control. Mine also went into the atti mode withoit showing it on the remote.

Not sure what DJi will so but im praying. I had 5m of wind -2 degres outside and clear sky, but it was dark so that wasnt helping at all. Since that time ive been flying P4 there for many hours with the wind blowing up to 14 meters and no problem at all :(

Must be a bug wich DJi has to resolve.


Sent from my iPhone using PhantomPilots
 
I was flying my P4P weeks ago, after 1100meters away from hp i lost the signal to the remote..

Must be a bug wich DJi has to resolve.

Very similar to me, I also didn't get a notification of the mode switching.

And now that you say it, I assumed that it crashed in the wall when I was still connected to it, but the last picture on the screen was actually from a few meters above the water surface. So chances are that I lost connection first and then I drifted into the wall. Would explain the last few seconds of out of control.

Another thing seems very weird to me. According to the log file the drone still moved 16 m away from the home point after Atti was activated. Measured how? By coordinates. The longitude and latitude are changing constantly. How can this be if the GPS isn't working?
 
I was flying my P4P weeks ago, after 1100meters away from hp i lost the signal to the remote, i went into my car and drove like 150meters away from him where he was on the way to hp, the P4P asked do you want to land - and i pressed no so he followed the route back to ho. But when he had like 800meters left he lost gps signal - remote signal and came up with some compass error. The wind was blowing from the east so he hoowered for 26 minutes (if my canculate) is right to the west so he could be somwhere between 1-4kilometers away from the homepoint. Ive spent many hours walking and flying my friend drone trying to find him but with no luck i lost my brand new P4P.

Was it my fault ? NO cause when you loose the connection and he looses the gps signal or compass the wind takes the control. Mine also went into the atti mode withoit showing it on the remote.
Not sure what DJi will so but im praying. I had 5m of wind -2 degres outside and clear sky, but it was dark so that wasnt helping at all. Since that time ive been flying P4 there for many hours with the wind blowing up to 14 meters and no problem at all :(
Must be a bug wich DJi has to resolve.
Your app has a "black box" data recorder that can often explain what happened.
If you want to learn from the experience and be able to avoid similar occurrences:

Go to https://www.phantomhelp.com/LogViewer/Upload/
Follow the instructions to upload your flight record.
Come back and post a link to the report it provides and someone here might be able to analyse it and give you an understanding of the cause of the incident and perhaps a likely search area.
 
What irritates me also is that after switching to Atti there are a lot of "GPS Position NoMatch" errors. So even when having 11 satellites again (row 1961, 3m 23.9s) it stays in Atti mode, although of one satellite type there would have been 6 then in any case. It shows the NoMatch error there and at 35 other records.

Sent from my BLL-L22 using PhantomPilots mobile app
That error is a problem. Some are losing control with that error. I had it pop up a block away with 19 sats and I had to bring the bird home in Atti by eye as it had my location on the map a mile away. There have been others.
 

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