Standard Crashed Phantom Today. Pls Help Me Analyse Crash.

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Hi

Today, I crashed my Phantom, just as I was beginning to get confident using it (only about 15 flight 'days out' in total.)

I went to a rural spot beside a lake that I am familiar with; I like the wide open spaces with minimal radio interference.

I spotted a large concrete surface beside the lake and thought that looks 'perfect.' Put the drone down, waited for it to warm up, until I was able to do an auto 'take off.' Took off, and as soon the drone got about 5 foot in air, I heard the dreaded words from the app 'ATTI Mode.' I have to highlight there was no indication it was in ATTI mode before I took off.

Of course, I'm not used to ATTI mode. I don't often get to use the drone due to weather in my country, and on the few days I get to use it, it's always in GPS mode.

The thing started swinging about wildly at speed, and I could barely control it. I had the choice of crashing into a very large concrete block, a small tree, or the lake. Of course I started to panic.

I crashed landed it back on to the concrete surface, it was a nasty landing, it bounced, and ended up propeller side down. After examination, I've chipped at least one propeller. There are no cracks on the body, and the unit still seems operational (did a short test flight later.)

I suppose I am lucky it wasn't smashed to smithereens, or landed in the lake. However the experience has massively dented my 'drone confidence.'

I am presuming it went into ATTI mode, because the nice smooth surface I took off from was probably reinforced concrete which is full of metal? I don't understand why I got no warning BEFORE taking off. I took off, and within a second was wildly darting all over the place.

Does my reinforced concrete idea sound like a realistic reason for it going into ATTI mode?

Also, why was the ATTI mode so wild? It seemed like it was going full speed horizontally. I just couldn't figure how to land something like that, so crashed it.

I'll be honest I really don't want to experience this again, and would be grateful for any suggestions on how to avoid a re-occurence.

Thanks in advance.
 
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Did the controller give you the 'home point updated' verbal message before you took off? You also don't say what the status of your GPS was. How many satellites was it locked on to prior to take off? The answers to these two questions will help guide you to further possibilities as to why it was in ATTI mode
 
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@Newzealandlandscape. Thanks for getting back to me. I'll be honest I cannot remember now. The only thing I'm sure of is it said 'ATTI mode' AFTER it had taken off. From then it was just 'panic mode.' I am wondering why did I get the ATTI mode warning after takeoff, and not before?

EDIT - Went through the flight logs on DJI GO app. I did indeed take off in GPS mode, with 8 satellites locked in. Immediately after takeoff, it reported a 'compass error' and went straight into ATTI mode.
 
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I have had similar experiences! I just realised you have a P3 I don't know if that's the same software as P4 but there is a remote possibility that your drone took off before it had updated its home position. ( You said it warmed up for 10 minutes so that should be plenty time to fix its new position). I wait till the drone tells me its updated its home position so I know it has an exact fix on its position. MIne can take a while to lock onto, say, 12+ satellites and at that point it gives me the home point updated message. Sometimes it seems to take longer than others but I NEVER take off till I have that reassurance. Without it the drone thinks it's somewhere else with nasty consequences!
Recalibration of compass and IMU is a good safety precaution in any event.
My sympathies for that sickening feeling as you lose control. My drone did that and, like yours, sped off at increasing horixontal speed reaching an incredible 60KM for a second or so (well that's what the log said). In my case I suspect the problem was caused by wind gusting that exceeded the ability of the drone to stay in the right attitude and it lost the GPS signal or the compass was decalibrated if there is such a word!
 
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@Newzealandlandscape. Thanks for the ideas. I didn't wait for 10 minutes before takeoff. I always takeoff when the IMU has warmed up, and 'auto takeoff' becomes an option. This normally takes about a minute or two.

I'll be honest I doubt the Phantom could take off before managing to update it's home position (there must be rigid software rules to avoid this.)

I am wondering if the concrete take off point caused the compass to malfunction immediately after take off. In my opinion the drone should never have taken off it that was the case. I'm pretty disappointed to be honest.

ps. I did not calibrate the compass before this flight. I used to do it before every flight, but read posts on this forum that it's not necessary.
 
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Good .... FYI, I sometimes takeoff from a rebar filled Helipad that results in "compass error" until I raise my P4 above my head and perform a hand launch. My first P2 crash was from a rebar filled concrete garage before I knew better.
 
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@lonjsnyder. I've had compass errors before while the drone is sitting on the ground, and of course I don't take off in this situation. What bugs me about today's crash, is the compass error kicked in one second after take off, resulting in a crash.

Do you get compass errors on the ground (good,) or seconds after take off (very bad)?

Thanks.
 
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@lonjsnyder. I am now wondering if I should go back to my old method of doing a compass calibration before every flight? Maybe then today's near disaster could have been avoided. Like I mentioned there are many posts out there saying compass calibration before each flight is not necessary, so I'm very confused now.

UPDATE - I've just read the DJI Phantom manual, and it says 'ALWAYS calibrate the compass in every new flight location.'

I've read posts suggesting the contrary (which I followed.) I also believe that if I calibrated my compass before every flight this afternoon, I would not have ended up crashing it into a concrete surface at high speed.
 
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Please don't be confused, once I have a good calibration performed in an open field, I do not calibrate again until I've traveled very far and if the bird isn't flying straight… There is lots of risk of doing compass calibrations unnecessarily often and getting a bad calibration due to unseen surrounding magnetic interference
 
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This advice is taken directly from the DJI manual, and after today's experience I will follow it. I reckon if I had carried out a compass calibration at the spot of my crash today, the calibration would have failed, and I would never have flown.


'IMPORTANT: Always calibrate the compass in every new flight location. The compass is very sensitive to electromagnetic interference, which can produce abnormal compass data and lead to poor flight performance or flight failure. Regular calibration is required for optimal performance.

Ensure the compass is calibrated. If you did not calibrate the compass as part of your pre-flight preparations, or if you have moved to a new location since the last calibration. '
 
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Your Phantom went into atti mode because you had screwed up the compass.
This always happens with a compass error.
This advice is taken directly from the DJI manual, and after today's experience I will follow it. I reckon if I had carried out a compass calibration at the spot of my crash today, the calibration would have failed, and I would never have flown.

'IMPORTANT: Always calibrate the compass in every new flight location. The compass is very sensitive to electromagnetic interference, which can produce abnormal compass data and lead to poor flight performance or flight failure. Regular calibration is required for optimal performance.

Ensure the compass is calibrated. If you did not calibrate the compass as part of your pre-flight preparations, or if you have moved to a new location since the last calibration. '
Sorry ... NO ... 100% No
What you are quoting is quite wrong and DJI have finally changed the compass calibration section of the manuals to advise not calibrating the compass at all.
If you calibrate the compass close to a magnetic influence (steel and reinforced concrete) you will always get a compass error when you fly away from that magnetic influence back into the earth's normal magnetic field.
It is sometimes possible to "successfully" calibrate your compass in a magnetically bad location.
Here's an example of how that works out for calibrate-every-flight club members:

The principle to stick to is get a good compass calibration in a magnetically clean area and just leave it alone.
I spotted a large concrete surface beside the lake and thought that looks 'perfect.' Put the drone down, waited for it to warm up, until I was able to do an auto 'take off.' Took off, and as soon the drone got about 5 foot in air, I heard the dreaded words from the app 'ATTI Mode.' I have to highlight there was no indication it was in ATTI mode before I took off.
This explains clearly what caused the problem.
NEVER launch from reinforced concrete or steel. Never.

There have been way too many incidents just like yours.
If you want a technical explanation read this:
Looking for Trouble ??
 
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I was just thinking, the above advice is taken directly from the manual 'always calibrate in every new flight location.' If that is the case, how come when I
Your Phantom went into atti mode because you had screwed up the compass.
This always happens with a compass error.

Ok, point taken. However, I didn't know it was reinforced concrete (I am only guessing it was.) What I just don't get, is why didn't I get a 'compass calibration error' before take off? It appeared seconds after take off, which caused chaos.

I watched the video you posted which was interesting, and have to point out I did no calibration after taking off from the concrete pier today.

Is it still possible for reinforced concrete to mess up a drone's compass, even though no calibration took place at that location?
 
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Is it still possible for reinforced concrete to mess up a drone's compass, even though no calibration took place at that location?
Absolutely... I have read a lot in this forum and one of the feedback is to never take off from concrete, metal platform, car surface, etc. Anything that is not grass or the natural outdoors environment where you don't find interference with the compass.
 
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I've downloaded the Teslameter app also. Did a test with my hi-fi speakers, placed the Teslameter app close to them, and it gave a 'red alert,' so it could be useful.

Some more questions, my drone landed upside down. One propeller was obviously damaged. Should I throw the whole set of props in the bin, in case there is any subtle damage I can't detect?

Also why was the ATTI mode so crazy? I could barely control the thing, and had no idea how you could land something doing 15mph horizontally.

I'd be to even practise in ATTI mode again if it's so crazy, even on a huge beach (sadly none near me.)

Thanks.
 
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Normally, ATTI mode is fairly stable except for drifting in the wind ... if wind is light, then it's easy. Your experience was different due to something else, most likely the concrete pad with rebar. Yes, after your crash, you should replace all props, perform both an IMU calibration and compass calibration.
 

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