HELP! P3 Professional went out of control and crashed.

[skipilot1]

If you look at the warnings it had gps issues throughout the entire flight at various points of the map away from the takeoff site so unless he calibrated it badly from that concrete structure to begin with it would have cleared up when he got into the air.

Pasted:
"Warning:Satellite Positioning Off. Fly with caution"

I had my p3p act wonky one day similar to poster here, scared the crap out of me but I was able to land despite it feeling like it wasn't responding to stick input properly. Did a heart pounding recalibrate of the IMU/compass and it flew fine in same location next day. It was nerve wracking but I guess I responded appropriately. Didn't have any further issues... and I survived without damage...

I always do a 2nd take of my surroundings before calibrating over my current known good compass calibration.

Did you check your sensor readings before takeoff? That is something that should always be part of a pre-flight checklist. Your compass should read between 1450 and 1600.

 

[HWCM]

I land on my neighbors steel shed a few times and have never noticed this. Land and take off actually.

If you have a good compass calibration you would only get a compass error in flight if you fly into an area with a changed magnetic field.
The best strategy in this situation is to back away or climb above the magnetic influence back into the earth's normal magnetic field where your compass is calibrated to fly properly.

You can try this yourself by lowering your Phantom slowly towards the roof of your car or a steel roof shed.
As you get closer your Phantom will start to slowly spiral and if you get close enough, you will get a compass error.
Phantom starts to spiral as the magnetic effect becomes greater .... just climb away from it and spiraling stops.

 

[HWCM]

What about when you are 200 feet in the air over a forest and get a compass error? Or like the guy in the video posted who is flying over a creek in the wilderness and gets a compass error?
That explanation makes no sense. But it is what it is. I will just fly and enjoy it If the compass goes crazy during a flight I will hopefully get it under control, if not I guess DJI will have to replace it...LOL, right.

If you have a good compass calibration you would only get a compass error in flight if you fly into an area with a changed magnetic field.
The best strategy in this situation is to back away or climb above the magnetic influence back into the earth's normal magnetic field where your compass is calibrated to fly properly.

You can try this yourself by lowering your Phantom slowly towards the roof of your car or a steel roof shed.
As you get closer your Phantom will start to slowly spiral and if you get close enough, you will get a compass error.
Phantom starts to spiral as the magnetic effect becomes greater .... just climb away from it and spiraling stops.

 

[syotr]

For the entire 3.5 mins this flight lasted the flight record is showing Compass Error or Yaw Error (which is basically the same thing).
The Phantom is telling the operator that the compass data is garbage.
Whenever the GPS positioning error came up, the Phantom automatically switched to atti.

Switching to atti causes the flight controller to ignore GPS data input.
But the compass is still required to maintain controllable flight and be able to fly straight.

When the compass data is garbage, switching to atti isn't much help.

I have to disagree here. The Naza and Naza Lite controllers are sold without the GPS module (which also contains the compass.) They fly just fine in Atti mode.
If you have a compass, in course lock mode, Atti and compass are used together, but otherwise Atti mode does not need the compass.

 

[syotr]

I cant accept it. It would be literally unacceptable if the phantom relied on compass sensor data that
1) it knows is unreliable or unusable at that moment, and even reports this
2) is not needed at all in attitude mode, as can be seen by flying any quadcopter that doesnt have one.

I mean no disrespect to Meta4, but I think he's wrong here and it will take more convincing evidence than the OP's log to make me change my mind on this.

Its believable that a slightly miscalibrated compass affects flight, compass and gyro data may be different and cause some unwanted heading adjustments, but the moment the phantom itself says the data is not usuable and you should take manual control, I dont buy it. Why would it even bother to detect and report a compass problem ?

I agree. Lots of users have had compass errors, switched to Atti and flown home without errors.

 

[Tenly]

Did you know the offered discounts are on refurbished P3's? I know because I bought one.

How can you tell if it's refurbished?
I just received a replacement for one I lost. How can I tell if it is new or refurbished?

 

[Meta4]

I agree. Lots of users have had compass errors, switched to Atti and flown home without errors.

But switching to atti doesn't shut off the compass.
If they have a small compass error they might get away with it but one like the OP is a different matter.

 

[Tenly]

Thats not conclusive at all. The pilot stated he never switched out of P GPS mode; the phantom did this a few times automatically, for relatively brief periods, but I cant tell from the logs if it was controllable then, or even if that is the same as manually selecting attitude.

Note that the software will instruct you to switch modes when this happens "Compass Error, Exit P-GPS Mode". I really hope that shouldnt not read 'Compass Error, Exit P-GPS Mode but you are still f*cked'.

I think we all agree its best to ensure good working compass, but if its true a phantom can not be controlled reliably in attitude mode with a failing compass, I would consider that a huge problem. Of all sensors, the compass is the one that is the least reliable and most easily influenced (and arguably, least necessary to maintain manual control).

Isn't it crazy that they give us a command to kill the motors but not a command to disable/ignore the compass?

I also thought that switching into ATTI mode would tell the phantom to ignore the compass and gps data and let me fly manually....

If the fact that you can't disable the compass were an oversight, they would have fixed it a long time ago - which means that they must have made it impossible to disable for a reason...but what reason could that be? All you need is the barometer to maintain altitude and gyros to maintain orientation. Why force us to fight a screwy compass in ATTI mode?

 

[Tenly]

With that being said does that lead you to believe this could have been some sort of abnormal error, maybe due to a software malfunction or something of that nature? This aircraft would still be here today if I was able to gain control, but the toilet bowl flush and the complete unheard of tone of the motors leads me to think something more went wrong. Again, I'm clearly not as knowledgable as the majority of you regarding the series of events here, but leading of the the chaos I believe I did everything as expected.

I'm really trying to get down to what DJI will have to say. I filled out the form and synced the logs today and have messaged with a person with the problem ticket.

I recently lost a phantom in the lake. I did not have the bird to send in. I filled out the same questionnaire as you and sync'd my flight records.

After a 2 week review - they replaced by phantom, camera, battery and props at a 100% discount - so if someone tells you they they won't replace a bird that you can't send them - they're wrong. It might not happen often - but I'm proof that it cab happen.

In any case - my issue was different than yours. I'll bet that after a review of your data, they'll offer you at least 30% off of a replacement drone and possibly even 50%. I've also heard that if you complain about the discount they offer, they'll someone's make it better with a "final offer".

I do hope that they do something for you though. Although the conventional forum wisdom says not to fly with anything but a fully charged battery - I don't think the operating manual says any such thing.

There may have been things you could have done differently or better when the incident occurred - but I don't think you did much of anything that contributed to the errors. As someone else mentioned - the compass errors should have cleared up when you flew away from whatever was interfering - unless you actually calibrated your compass on all that metal (did you?).

One other thing I dug up and sent them is the cached video from DJI Go. If you can retrieve that file - post it here for us to look at - and send it in to DJI as supplemental evidence. If you are using an iOS device, connect to iTunes, then on the right hand side of the screen - find the DJI Go app listed and look at the directory structure. You should see your "flight record" folder and you should also see a "videocache" folder. Go into the videocache folder and find the file that matches the flight in question. Copy it to your computer and then upload it! When you submit it to DJI, make a vague suggestion that this video file contains more evidence that you did not do anything wrong - and let them figure out what you meant by that!

Good luck. I know exactly how you feel right now. Don't wait for an email from them. Call them every 5 days asking for an update or if they need anything else from you. My case took 2 weeks. I've heard of others taking as much as 8 weeks.

 

[Meta4]

Why force us to fight a screwy compass in ATTI mode?

Don't give yourself a screwy compass and you'll never have that worry.
Too many people seem to think a compass error means that something is wrong with the compass.
As long as you don't give it a bad calibration, it means that the compass is fine but it's telling you it has detected a magnetic field different from the earth's normal field.

 

[HWCM]

That is not always the case.

Don't give yourself a screwy compass and you'll never have that worry.
Too many people seem to think a compass error means that something is wrong with the compass.
As long as you don't give it a bad calibration, it means that the compass is fine but it's telling you it has detected a magnetic field different from the earth's normal field.

 

[HWCM]

How do you get a video from the DJI GO app. I can only see a picture maybe every 5th flight. Never any video. Usually just one picture of when I first take off or land.

 

[Tenly]

How do you get a video from the DJI GO app. I can only see a picture maybe every 5th flight. Never any video. Usually just one picture of when I first take off or land.

It's in the directory structure underneath the app when you're connected to iTunes. There are a bunch of folders. You connect the phone to the computer - you don't access it via the DJI Go app itself.

 

[HWCM]

Ahhhh, thank you berry much

It's in the directory structure underneath the app when you're connected to iTunes. There are a bunch of folders. You connect the phone to the computer - you don't access it via the DJI Go app itself.

 

[Tenly]

How do you get a video from the DJI GO app. I can only see a picture maybe every 5th flight. Never any video. Usually just one picture of when I first take off or land.

If you still don't know what I mean, I can take some screenshots for you. Are you using an iOS device?

 

[HWCM]

Thank you, but I got what you mean. Yes I have a ipad mini4

If you still don't know what I mean, I can take some screenshots for you. Are you using an iOS device?

 

[Tenly]

Thank you, but I got what you mean. Yes I have a ipad mini4

I found it by accident but it appears to be a cached version of the 720p lightbridge stream from the phantom to DJI Go.

 

[Vertigo]

Those words come straight from the manual.
An alternative interpretation is ... The aircraft only uses its barometer (for stabilisation)
Atti mode uses all other sensors, gyro, barometer and compass.
Manual mode (if it was available) would use no sensors.

cough. No, thats not how it works. You cant do anything with a baro alone, let alone without any sensors. Its basically impossible to fly a multirotor without at the very least gyro sensor stabilization to measure angular velocity. Gyro/acro/manual mode is the simplest form of stabilization where the craft does not know what is up or down, it doesnt know its orientation, it wont self level, it will just resist rotation if its not commanded to rotate. If you fly in a certain attitude, like 40 degree forward, it will maintain that with sticks neutral. To get back to level, you need to pull back on your pitch control stick until it is level. You can do flips, fly inverted etc in this mode. DJI has never implemented this AFAIK, and I would expect 95% of its customers to crash in this mode. It is the most used mode on racing quads and for aerobatics.

The next step up is adding accelerometer data (absolute orientation) and having the quad automatically hold a certain bank or roll angle that corresponds to your stick position. So if you center the stick, the quad autolevels. To fly forward you must maintain forward stick input. This mode is typically called attitude or angle mode, it requires neither a baro nor a compass, just gyro and accelerometer data.

A baro is optional in any flight mode and only allows altitude hold where the throttle stick controls altitude rather than motor power. Which again is the default for DJI. IF you add a compass, its usually called mag mode or course lock, and as someone mentioned, DJI also used to call it just that with the Naza. Its needed for GPS navigation and position hold modes, because GPS only tells you your position, but not the direction the quad is facing, so it wouldnt know in which direction to correct its position. Compass data is not needed for attitude mode on any other flight controller, including the DJI Naza.

Anyway, how about we settle this once and for all. Who is brave enough to test? Disabling the compass as someone mentioned is not entirely conclusive, what would be conclusive is someone taking off normally, hovering in attitude mode, and then putting a rare earth magnet right on the magnetometer. If the craft remains controllable its pretty obvious you do not need valid compass data. If it does go out of control, anyone who's ever lost a drone should join for a class action law suit against DJI.

If anyone is up for this challenge, please be careful.

 

[Tenly]

cough. No, thats not how it works. You cant do anything with a baro alone, let alone without any sensors. Its basically impossible to fly a multirotor without at the very least gyro sensor stabilization to measure angular velocity. Gyro/acro/manual mode is the simplest form of stabilization where the craft does not know what is up or down, it doesnt know its orientation, it wont self level, it will just resist rotation if its not commanded to rotate. If you fly in a certain attitude, like 40 degree forward, it will maintain that with sticks neutral. To get back to level, you need to pull back on your pitch control stick until it is level. You can do flips, fly inverted etc in this mode. DJI has never implemented this AFAIK, and I would expect 95% of its customers to crash in this mode. It is the most used mode on racing quads and for aerobatics.

The next step up is adding accelerometer data (absolute orientation) and having the quad automatically hold a certain bank or roll angle that corresponds to your stick position. So if you center the stick, the quad autolevels. To fly forward you must maintain forward stick input. This mode is typically called attitude or angle mode, it requires neither a baro nor a compass, just gyro and accelerometer data.

A baro is optional in any flight mode and only allows altitude hold where the throttle stick controls altitude rather than motor power. Which again is the default for DJI. IF you add a compass, its usually called mag mode or course lock, and as someone mentioned, DJI also used to call it just that with the Naza. Its needed for GPS navigation and position hold modes, because GPS only tells you your position, but not the direction the quad is facing, so it wouldnt know in which direction to correct its position. Compass data is not needed for attitude mode on any other flight controller, including the DJI Naza.

Anyway, how about we settle this once and for all. Who is brave enough to test? Disabling the compass as someone mentioned is not entirely conclusive, what would be conclusive is someone taking off normally, hovering in attitude mode, and then putting a rare earth magnet right on the magnetometer. If the craft remains controllable its pretty obvious you do not need valid compass data. If it does go out of control, anyone who's ever lost a drone should join for a class action law suit against DJI.

If anyone is up for this challenge, please be careful.

You should offer a $5 prize to whoever successfully accomplishes this...

 

[Meta4]

cough. No, thats not how it works. You cant do anything with a baro alone, let alone without any sensors. Its basically impossible to fly a multirotor without at the very least gyro sensor stabilization to measure angular velocity. Gyro/acro/manual mode is the simplest form of stabilization where the craft does not know what is up or down, it doesnt know its orientation, it wont self level, it will just resist rotation if its not commanded to rotate.

Like I said ... atti mode uses all sensors except GPS and VPS.
When said .. The aircraft only uses its barometer (for stabilisation)
I meant that in P-GPS mode the Phantom uses GPS for horizontal and barometer for vertical stabilisation.
In atti it only has vertical stabilisation -not horizontal.