P3 drift and crash

LOG shows poor GPS signal on a number of occasions.
Around four minutes in compass performance was reported as very poor also.

As to the vision positioning system you were two high off the deck for it to help,
From 3:48 the Phantom was in the shrubbery and the poor compass and GPS indications are all after that - so not relevant.
 
So now, following the latest firmware fix for recent battery issues, we're starting to see Phantoms 'popping' out of one mode to another.
I guess we could blame the firmware. Going to ATTI when GPS performance is poor should be expected. We saw that before the latest firware application.
 
Sorry to learn you ended up in the srub but sounds like you will be up flying again in no time.

From the log it seems you had your work cut out for you and were unlikely to be getting much assistance from the phantom in flight.

LOG shows poor GPS signal on a number of occasions.

Aroumd four minutes in compass performance was reported as very poor also.

As to the vision positioning system you were two high off the deck for it to help,.

Replace the props and take it slow and gentle. Maybe in a new location for the next flight

The compass went through a variety of modes after it crashed - before then, my visual flight record tells me it was in P-GPS until it suddenly hit P-OPTI and started drifting to the trees. Right before it hit them, it went back to P-GPS.

I've only ever flown it slowly because I'm totally new to this - I fly it like a granny, LOL.

What I don't understand is why there is such a discrepancy between the text flight log which says the P3 was in Atti the whole time, and the DJI Go visual flight record, which you can see by the pics tells me it was in P modes.

I'm not even game to fly it right now because I have no idea what it might do next. I don't know if there's a problem with the drone itself??


Sent from my iPhone using PhantomPilots mobile app
 
I guess we could blame the firmware. Going to ATTI when GPS performance is poor should be expected. We saw that before the latest firware application.
From 3:48 the Phantom was in the shrubbery and the poor compass and GPS indications are all after that - so not relevant.
Noted, thank you. My commentary on GPS is of no relavence either for same reason (looking at the timeline). Not sure what that leaves us with....
 
What I don't understand is why there is such a discrepancy between the text flight log which says the P3 was in Atti the whole time, and the DJI Go visual flight record, which you can see by the pics tells me it was in P modes.
Perhaps there is not a discrepancy after all. I compared your flight log with a lot of mine where I know I was flying P-GPS -- and, my logs also showed "GPS_Atti" as the mode. The mode shows "Atti" when there isn't a good GPS signal (I just did a test inside to verify). I'm not sure how many other modes show up in the flight logs. I was expecting to see "P-GPS", "P-OPTI", and "P-ATTI", but those modes never appear in any of the logs I looked through.

Your logs indicated that you had a good GPS connection for the entire flight (up until your crash), so I'm not sure why your Phantom switched to P-OPTI. Per the manual, that means the GPS signal was not sufficient. And, since you were not on the sticks to correct the position, your Phantom was drifting with the wind.

So, it seems the only unanswered question is why wasn't the GPS signal sufficient. You had 15+ satellites prior to the first motor obstruction error (the crash). The manual does not indicate the satellite count needed for a sufficient GPS signal, but I'm assuming it's 6+ satellites since that's what the P2V+ requires to fly in GPS mode.
 
I uploaded some more of my flight records - bear in mind, I only got this P3 three days ago...and every single record says I've been flying in Atti mode...I have never put the controller into the A position, it's been on P since day 1. My DJI Go app tells me I've been flying in P mode pretty much the whole time, yet the text files tell me something totally different. I've no idea what to do, whether to return it for a replacement, whether it's a malfunction or what...I'm too frightened to fly it now considering everything I've learned about the discrepancies and the fly away yesterday evening.

Sorry, I posted this before seeing your comment above, Msinger.
 
I can see in the flight log of this event that with the A, B, C, etc, it hasn't even recorded where the drone actually encountered the issue of changing into P-Opti - the letters only show up at the take off point and the crash site.
 
So, it seems the only unanswered question is why wasn't the GPS signal sufficient. You had 15+ satellites prior to the first motor obstruction error (the crash). The manual does not indicate the satellite count needed for a sufficient GPS signal, but I'm assuming it's 6+ satellites since that's what the P2V+ requires to fly in GPS mode.
Here's an idea .... Did the Phantom get into a position where tree cover may have obscured enough of the sky to lose GPS satellites?
If it did, and there were leaves within a few metres below the P3, the VPS would have attempted to fix on the leaves and branches below but failed to because it needs a simple surface with a clear pattern.

DJI have never explained the required number of sats for the P3 but it's not as simple as just one number.
The GPS and Glonass run in parallel but not together. You still need a full minimum number for each system.
Maybe that's 4,5 or 6 but just having 6 sats probably won't be enough because the probability would be that you'd have something like 4 GPS + 2 Glonass.
I'm not even game to fly it right now because I have no idea what it might do next. I don't know if there's a problem with the drone itself??
You should be right to fly again after an IMU calibration indoors on a perfectly level surface.
Disable VPS and take it gently in an open area.
Fly and hover 5-10 metres away for a while, watching the indicators in the app and see how it goes.
I think there's a high probability you'll be happily flying again very soon.
 
Thanks Meta4...it was flying on the open golf course, so just green grass beneath...and it wasn't at a low altitude, it was a fair distance up in the air.

I've written to DJI to ask why it might have suddenly kicked into P-Opti mode - not sure if they'll reply. I outlined the same things as I've mentioned here already.

cfaa864bf629eaef647fdd129954caec.jpg



Sent from my iPhone using PhantomPilots mobile app
 
I have some footage here...

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.


Sent from my iPhone using PhantomPilots mobile app
 
I literally just had the same issue. My second time out flying, updated firmware and re-calibration. Had strong GPS, got it off the deck and drifted straight into a wooden fence. Didn't take any real damage but shook my confidence a bit. Anyway someone can scrub my flight log and tell me what happened?




Sent from my iPhone using PhantomPilots mobile app
 

Attachments

  • DJIFlightRecord_2016-01-14_[21-09-28].txt
    39.7 KB · Views: 251
Last edited:
msinger why would it switch to ATTI? Basically right now with my first couple of flights I ONLY want to be in GPS. In fact I can't imagine why anyone would want to fly without the assistance... Anyway my APP was reporting GPS and something like 11 satellites so I thought I was good.
Mind you it was dark, would that play a role?
You are correct too... Flying in too tight a space... **** got real fast. I just trying to minimize the damage.


Sent from my iPhone using PhantomPilots mobile app
 
why would it switch to ATTI?
Your flight log indicates you lost GPS due to a "YAW_ERROR_LARGE" error. I did some googling and found a lot of people talking about that error, but nobody mentioned what it means.
 
msinger why would it switch to ATTI? Basically right now with my first couple of flights I ONLY want to be in GPS. In fact I can't imagine why anyone would want to fly without the assistance... Anyway my APP was reporting GPS and something like 11 satellites so I thought I was good.
Mind you it was dark, would that play a role?
You are correct too... Flying in too tight a space... **** got real fast. I just trying to minimize the damage.

It lost signal with the GPS sats...I know exactly where you're coming from because I went through the exact same thing - I had good satellite coverage and Safe to Fly and still lost signal, it started to drift faster than I'd been flying, I'd only had it two days, and it got lodged in a tree 80m away from where I was standing, and then crashed to the ground. I only want to be in GPS too, although there are situations where it can drop out, depending on the environment around you. But I have a feeling this is a 1.6 firmware issue, more and more people are starting to report on this happening.
 
If anything it makes me want to learn in ATTI mode as a fail safe in case this happens again but jeesh... Watching $1300 fly right into a fence was hard to swallow... Imagine your tree situation was about the same. Man I was so excited to start flying this thing... Now I'm scared shitless.
Someone please stroke my ego or give me some pointers for successful flight? Always calibrate... Etc.


Sent from my iPhone using PhantomPilots mobile app
 
It's a love/dread relationship with these things. I find getting a good warm up time once it's in the air helps to relieve the tension. Once I feel good about it at 12 feet or so, like the voltage readings, like the hover, the sensor readings, etc. I find I can zip around pretty stress free. Not as much actual flight time but much a more enjoyable time while I'm in the air.
 
Someone please stroke my ego or give me some pointers for successful flight?
For your last flight specifically:

- Don't fly in the dark
- Fly in a wide open area until you are really good on the sticks
- Don't take off with a 67% charged battery
 
  • Like
Reactions: Meta4
If anything it makes me want to learn in ATTI mode as a fail safe in case this happens again but jeesh... Watching $1300 fly right into a fence was hard to swallow... Imagine your tree situation was about the same. Man I was so excited to start flying this thing... Now I'm scared shitless.
Someone please stroke my ego or give me some pointers for successful flight? Always calibrate etc

I paid $1700 (Australia) and was absolutely devastated - it landed in a massive blackberry thicket and I couldn't find it. I had to go home and return with a hedge trimmer and literally cut my way to it - I was covered in thorns and scratches and blood when I was done but thankfully I spied the red light and managed to find an angle to approach it. It was a terrifying experience.

One thing I can't find in the manual is that it's essential to do an IMU calibration when you first get it. I hadn't done that as I wasn't aware it was something you had to do.



Sent from my iPhone using PhantomPilots mobile app
 
Last edited:
One minute I'm GPS... 20 seconds later I get kicked to ATTI and am in a fence. Proof is in the screen shots.
ef3e3ce5412758c7bccc53d8c7347cf5.jpg



Sent from my iPhone using PhantomPilots mobile app
 

Members online

Forum statistics

Threads
143,066
Messages
1,467,358
Members
104,936
Latest member
hirehackers