Arducopter starts to circle and crashes

Hi there

Today my copter crashed after some fpw flying while parked in loiter mode (10/15m alt). It started to fly circles (aprox 5m diameter) and suddently picked up speed and circled down...

Luckely there was no damage because I managed to slow it down and level the copter before impact.

I checked the logs of the flight, and there sems to be kind of oscillating in the roll_in / roll and also in pitch_in / pitch values... easy to find, just graph this values and the baro_alt.

As I said, I had parked the copter and was checking the screen, the radio out of reach.

Has anybody an idea what caused this circle inputs? Would be very greatful for any suggestions or solutions!


copter is a a 650mm quad with HD3542 motors, 13x4 blades, with equipment aprox 2.8kg.

regards andreas

2013-02-24 14-20 8.log

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  • Hello!

    I have the same problem.

    Have you eliminate yours?

  • Hi, my hexa has been flying Ok for the last 4 months, have not changed anithing but FW, now it takes off and hovers Ok until I touch rudder (level mode), then it starts to spin and ocilate.  Changed my PIDs and have reached a point where right rudder won't generate much trouble, but right input will result in spining right and oscilating, have made it to land relativley safe, but I can´t keep on flying like this.  Any ideas? I have calibrated compass meany times, even upgraded to the new GPS -Compass combo but it behaves he same.  Please help me.

  • Hi everybody,

    One week ago I have made some intensive comparison tests between Firmwares an settings on my two copters. The Quad is in services since 6 months and I have never encountered the "Spiral of Death" as on my Octo in Loiter mode. The both bird have the same setup, only the difference is that one is Quad and the second is Octo and for sure the second APM 2.5 came from another production batch.

    Few weeks ago the second APM was flashed with the same good old AC2.7.3. (as in the first one) and because I have already observed some strange behaviors (only on the second which is on the Octo), I decided to test a tweaked FW2.8.1. on both copters. On the following picture you could see the difference between the two Loiters made with the Quad and Octo using the same FW, PID's and same weather conditions . For sure, the Octo need another settings as the Quad because is heavier but right now that's the result:

    3692647337?profile=originalAfter some PID adjustment on both copter, the Quad attitude is better but the Octo remains unchanged.


    1. I think this issue could be not associated to a specific FW because it was observed on AC2.7.3 and AC2.8.1. too, and also AC2.9.1. by others.

    2. It could be not associated to GPS issue because the modules exchanged between the copters give the same results

    3. Before to start spinning, a strong YAW drift it is observed. This could be the sign that the compass encountered electromagnetic interference but what is strange, on the Quad the ESC are almost near the APM and this behavior was never observed.

    4. Loiter, RTL or Auto modes are directly influenced from this issue and the only one way to get the control again is to switch to Stable mode back. This is the answer for crashes reported from pilots with poor flying skills or when the copter is too far away to see his position.

    On the next step I will perform a "brain transplant", I mean APM exchange between the copters, to determine if a hardware issue could be identified. I can any time reproduce this issue, also if is completely no wind. I have a lot of logs and following the instructions from Randy, I will compare the compass offsets between the copters.

  • I had the same issue & it was attributed to Loiter Speed and Rate Loiter.

    I've found that if I vary even a small amount from their sweet spot I get the copter going into an increasing diameter spiral whilst picking up speed. So obviously tune your other stability values as per the tuning guides first.

    FYI my values on a Quad are;

    Rate Loiter P:4.0  I:0.04  D:0.4

    Loiter Speed P:2.0  I:0.0

  • Hi Mike

    Thanks a lot for yor reply. If checked the tunig and lowered the Roll / Pitch I value a bit and he copter flies now better in Stabilize.

    About the problem, it seems to a magnetometer issue, see:

  • Hi Andreas,

    You are the fifth or sixth person to describe similar behaviour before a crash in the past few weeks.

    None of teh developers seem interested in responding to anything posted outside the '2.9 release' discussion.

    You might have more luck posting there.

    Just from my quick look at your log (uneducated guess) the copter seems to be struggling following inputs. If you check out Pitch-in to Pitch and Roll-in to Roll you will see what I mean.

    Are you running the default parameters for 2.9.1?

    Have you been through the tuning guide?

    It may be just out of tune parameters exacerbating a deeper problem.

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