Sudden takeoff in Althold and Loiter mode

Hello fellow pilots,

A couple days ago I was flying my quadcopter running on apm 2.6, wich was working fine.

Stab, Althold, Loiter and Auto mode worked flawlessly.

Until yesterday, when I switched my flightmode to Althold or Loiter, my copter accelerated to the sky.

Quickly I switched back to stabilize to get control. 

From my experience with apm I immediately thought it would be a badly covered barometer.

I removed the cotton ball, wich was covering the barometer and replaced it with some foam (same foam as inside pelican cases).

After that I took my lovely quad outside to test Althold and Loiter, still the same :(

During the flying in althold and loiter my throttle was at ~50%, my osd and telemetry doesn't show inaccurate altitude readings.

Also my Pilot maximum vertical speed always changes itself to this value, I can't change it neither via telemetry connection nor with usb connection. Could this be the source of evil in this case?


So i'm lost, I don't know what other things I could check.

I have attached my tlog of this evening where you can see the sudden gain in altitude like at 21:14:46.

I would be incredibly thankful with any help.


2014-08-10 21-13-38.tlog

2014-08-10 21-13-38.rlog

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  • I'm sure it has something to do with throttle setting in loitermode,

    • Thank you Kim,


      I tried changing the value to 500cm/s in standard parameters, but it would always change back to the faulty 327637cm/s.

      Only when I changed it in full parameters list it did finally keep the value of 500cm/s



      • Hi Robert

        did it solve your problem ?

        • Hi Kim,


          My copter is now flying as it did before, loiter and althold works great.

          My throttle setting now keeps the value of 500 cm/s.




          Thank you very much

  • I am having the same issues with my quad at the moment. I have done some reading and found the manual of Arducopter stating that take off in Alt hold and Loiter mode suggests that the vibrations on the APM is to hectic. I did what they suggested and found that for some reason my Z-Axis vibration is outside the suggested targets. 

    If I fly a 4S lipo, the take off is much better but still there, however, when I put it in Loitre mode ... the copter drifts off to the right. I also have not had any time to look at this but any suggestions will be welcome. 


    • Johann, thank you very much for your reply.


      I will try rearrange my wiring around the apm to minimize the vibrations and look at my logs for x/y/z vibrations in a coule of hours.

      Will post the results and my findings ASAP.


      Again, thank you


      PS: looking at your name I assume you're dutch too, wich area are you from (just curious). I'm from Den Bosch FYI.



      • My copter is fully functional now, there were too many wires translating vibrations to my apm via the connections. I loosend up the wires so my apm could move completely free.

        Johann considering your problem with the drifting to the right, I suggest you make sure your apm can move freely. Use vibration foam underneath if you haven't already.

        Also recalibrating your accelerometer, run autotrim, use save trim and run the autotune proces may solve your problem.


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