HELP! P3 Professional went out of control and crashed.

[Vertigo]

Ive been googling to find out what "speed error" actually means, since there is no airspeed sensor on the phantom. Im still not sure what it means, but searching I came across countless fly aways that seem quite similar to what the OP experienced. For instance:

or this one:

And many, many more.

I cant say I understand what is going on, maybe Meta4 is correct and compass errors, even when detected, can result in loss of control, even in attitude mode, which I would find an unforgivable bug by DJI.

But I also cant help but notice that in pretty much all these cases I see lots of water. Could be coincidence, I cant think how it could impact the drone, other than the vision system, which I dont think can explain these. But I found it striking nonetheless.

 

[sethtinsley]

Ive been googling to find out what "speed error" actually means, since there is no airspeed sensor on the phantom. Im still not sure what it means, but searching I came across countless fly aways that seem quite similar to what the OP experienced. For instance:

or this one:

And many, many more.

I cant say I understand what is going on, maybe Meta4 is correct and compass errors, even when detected, can result in loss of control, even in attitude mode, which I would find an unforgivable bug by DJI.

But I also cant help but notice that in pretty much all these cases I see lots of water. Could be coincidence, I cant think how it could impact the drone, other than the vision system, which I dont think can explain these. But I found it striking nonetheless.

I'm with you man. Something is creating this same issue for a number of people with similar circumstances. These videos are scary and that second one is very similar to my event. Lucky for him he got it to come back. Live and learn at this point.

 

[flyNfrank]

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.

No doubt your A/C had serious issues from the get-go of this flight. There was no warnings prior to flight. And my argument with DJI would be,....why did Auto Takeoff allow the A/C to launch if there in deed was problem of any kind.

 

[sethtinsley]

No doubt your A/C had serious issues from the get-go of this flight. There was no warnings prior to flight. And my argument with DJI would be,....why did Auto Takeoff allow the A/C to launch if there in deed was problem of any kind.

Got it, thanks for the advice. The ticket is turned in and is in process, I'll post the outcome whenever I get it. I will definitely use that argument if needed. Thank you!

 

[MikeyOnline]

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'm finding it difficult to even form an opinion on this one. Seems like the AC did some things it shouldn't have done but they may argue that you did something you shouldn't have done (taking it off below battery warning level). Let's just see what they say. I wonder if they did much testing with the AC taking off below the warning level? It's possible that some of the logic in the bird depends on being able to monitor the battery and it crossing those thresholds while in flight... meaning that maybe some stuff didn't work right because it had no opportunity to warn you that the battery level had dropped below the set warning. Just a thought. Seems prudent to let them get back to you before making any more assumptions.

Mike

 

[sethtinsley]

I'm finding it difficult to even form an opinion on this one. Seems like the AC did some things it shouldn't have done but they may argue that you did something you shouldn't have done (taking it off below battery warning level). Let's just see what they say. I wonder if they did much testing with the AC taking off below the warning level? It's possible that some of the logic in the bird depends on being able to monitor the battery and it crossing those thresholds while in flight... meaning that maybe some stuff didn't work right because it had no opportunity to warn you that the battery level had dropped below the set warning. Just a thought. Seems prudent to let them get back to you before making any more assumptions.

Mike

Yeah I just really have always been under the impression that it's best to get your batteries low prior to charging them so they don't form a memory is what I was told (similar to cell phones). Unfortunately I was just hovering low and trying to run my battery down was the intention, turned into one hell of an shitty adventure after that.

 

[henick]

Yeah you should but you just need to plug the battery in and you'll see that if it's below 30%-ish (I think--dont know exact number) it will drain itself first. It begins blinking a single light for a while before charging. Where if you power on the battery first... then connect, it does the normal top up procedure. I usually top up and only near fully deplete once in 10 or so. Even if I needed to drain the battery just put it in the phantom and leave it idle. You don't need to run the motors at all.

Voltage sag for those of you who aren't electronic engineers can cause random things to happen because many electronic components have what are called brown out fail-safes that they perform when not properly powered. An arduino for example will reboot when it gets a voltage sag. That used to cause people that used GPRS modems to reboot when under load before it was discovered. For anybody that tried to create a diy home security camera ever, that's why the 5v ones would work fine until they would randomly reboot when sending some files. Not saying that's what is happening here but it is definitely very likely considering the other issues DJI has hard coded responses to recover from I expect it is identical. (Ever see propulsion limited? -- same bag of marbles)

They will probably give you some percentage off so it will be worth it anyway if you intend to purchase another phantom, I believe a 'speed error' is similar to a wheel speed sensor error on a vehicle or in this instance an 'etc error' but I'm only guessing based on context. One etc likely sagged and couldn't measure the speed of the motor. Considering the algorithms in the flight controller to account for wind you can see why that would be a problem and why it would down a bird but again I am only speculating without seeing the dat files.

 

[redredrn007]

I have never had this happen to me...yet... I have read several threads which describe out of control P3's and I land my P3 as soon as the battery gets to 30%. I have read that many of the times the loss of control problem can in part be attributed to a low battery ( less than 30%). The nature of this type of battery is that it does not evenly loose power, rather, it depletes somewhat logarithmically as the power lessens. Meaning, it may take 10 min to get to 50% and only 3 mins to get to down to 15%. Then, when the drone is more likely to act aberrantly when the battery gets critically low. You started out with the battery critically low. The potential for problems was compounded by your not stopping the flight as soon as you see the "compass error" , and you should ALWAYS set your home point whenever you fly no matter how brief the flight. The only time you don't have to set the home point is when you're changing the battery and restarting your flight from the same spot. Sorry you lost your drone!

 

[HWCM]

I am 99% sure you are correct about the compass. I have a few quads without a compass or you can turn it off. I think Meta4 just does not really understand how flight controllers work and what manual flying is. It absolutely makes zero sense for the P3 to turn off the GPS and leave on the compass in atti. It seems a lot of phantom pilots have only owned phantoms and do not understand that it is 100% capable of flying without a compass or GPS and it is simple to do, and fun. I know with APM, Pixhawk, Naza, etc etc if its in stabilize mode the compass and GPS is off so you can fly it manually because it is logical.

Yikes! Well, thanks. Seems like the longer I'm here, the less I feel like I know. I can accept that, but it still seems beyond odd to me as I don't see the logic. I've seen more than one log where a "compass error" is thrown and the AC switches to Atti mode automatically. I just don't see the logic in switching to Atti mode without pilot input on a compass error, and then still using the errant compass information plus shutting off the only (most times) reliable positioning system that is left (GPS). Seems like something else DJI needs to address. We all know we can fly just about any bird without a compass. I have several cheaper quads that don't have a compass and gyros don't drift fast enough that you can't keep a heading while flying on gyros only. At least if you have LOS.

Mike

 

[HWCM]

There is a video on youtube of a guy who pulled the compass off his phantom to show it can fly without the compass. Ill try to find it. He was having a similar discussion.

Yeah, sorry to get off topic a bit since this particular flight had a lot of issues. I'm more worried now about what I should do if I have a compass error during flight. I always make sure I have a good calibration and don't take off from metal surfaces, etc. But if I have a compass error during flight, I always thought I could switch it to Atti mode and fly it home like I fly my cheap quads that don't have a compass: by LOS and the gyros. Seems like my assumption was wrong. So what's the best course of action if you see a compass error and the AC starts flying in the wrong direction? If I can't switch to Atti and have true manual control... what to do? I just like to be prepared for such situations and I thought I knew what to do. Apparently not!

Mike

 

[Meta4]

Yeah I just really have always been under the impression that it's best to get your batteries low prior to charging them so they don't form a memory is what I was told (similar to cell phones). Unfortunately I was just hovering low and trying to run my battery down was the intention, turned into one hell of an shitty adventure after that.

Lipo batteries do NOT develop a memory - Old technology NiCad batteres do.
There was no need to hover to run your batteries down

 

[HWCM]

Lipos do not have a memory effect, cell phones also use lipo batteries, since the early 2000's.

Yeah I just really have always been under the impression that it's best to get your batteries low prior to charging them so they don't form a memory is what I was told (similar to cell phones). Unfortunately I was just hovering low and trying to run my battery down was the intention, turned into one hell of an shitty adventure after that.

 

[Meta4]

I am 99% sure you are correct about the compass. I have a few quads without a compass or you can turn it off. I think Meta4 just does not really understand how flight controllers work and what manual flying is. It absolutely makes zero sense for the P3 to turn off the GPS and leave on the compass in atti. It seems a lot of phantom pilots have only owned phantoms and do not understand that it is 100% capable of flying without a compass or GPS and it is simple to do, and fun. I know with APM, Pixhawk, Naza, etc etc if its in stabilize mode the compass and GPS is off so you can fly it manually because it is logical.

And a lot of people here are confused about the difference between atti mode and manual mode.
The P3 has no manual mode - the older P1 and P2 series had manual mode.
Atti mode is P-GPS mode without GPS or VPS. It is not manual mode.

 

[HWCM]

That is odd. What is the point then of having different flight modes if switching from one to the other or even why the flight controller would indicate a compass error if there is no way to fly without it? To that point, why would it indicate a compass error and then automagicly switch itself to atti?
I guess using logic is overthinking.

And a lot of people here are confused about the difference between atti mode and manual mode.
The P3 has no manual mode - the older P1 and P2 series had manual mode.
Atti mode is P-GPS mode without GPS or VPS. It is not manual mode.

 

[Meta4]

IMHO - the 'dangers' of metal are way over spoken about here. If you calibrate the compass in your car - yeah not a great idea. If you calibrate on concrete - its not an issue (do it all the time). Calibrate next to a 'gasp' metal building - not an issue. calibrate next to huge rare earth magnets or high voltage equipment running lots of amps? - not a great idea.

Despite DJI using the word metal, it's not metal that's the problem.
It's iron or steel - metals that are magnetic.
Brass, copper, aluminium won't have any effect - they may as well be wood or plastic.
And if you believe that calibrating the compass on reinforced concrete is no problem, you don't read as many threads as I do,
It's probably the most common cause of compass related crashes.
You may have got away with it because you were on non-reinforced concrete or maybe it didn't have much reinforcing but since you can't tell that by looking at concrete, it's a good policy to keep well away when calibrating the compass.

 

[HWCM]

From the DJI Wiki page. I guess we were right.
"A-mode (Attitude): GPS and Vision Positioning System are not used for stabilization. The aircraft only uses its barometer."
Phantom 3 Professional-Aircraft - DJI Wiki
I guess?

 

[MikeyOnline]

I guess using logic is overthinking.

Perhaps. Reality sometimes doesn't follow logic. I can't find the logic in getting a compass error and then turning off the only good positioning system remaining (GPS) while leaving what you know is an errant compass in control. But that's just me.

Mike

 

[Meta4]

From the DJI Wiki page. I guess we were right.
"A-mode (Attitude): GPS and Vision Positioning System are not used for stabilization. The aircraft only uses its barometer."
Phantom 3 Professional-Aircraft - DJI Wiki
I guess?

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.

 

[Meta4]

So what's the best course of action if you see a compass error and the AC starts flying in the wrong direction? If I can't switch to Atti and have true manual control... what to do?

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.

 

[skipilot1]

Did the start of your flight resemble this one of mine? I had a full battery though, and the bail out move was to gun it up, to avoid the trees as the only control I had was the throttle. My compass was hooped due my poor take off site (total dumb ***, not thinking that day). The classic toilet bowl circle yours made certainly points to compass issues.

Sent from my iPad using PhantomPilots mobile app

Toilet bowl effect is indicative of a compass problem. Hubsan had a firmware upgrade for its H501s and the forums were full of the same complaint. I had the same problem and finally the drone just flew away. There were plenty of videos of it but it was never quite so scary as when I saw it happening to my own bird.