Sudden change in altitude in auto mode or stabilized HELP!

Hi all,
I am suffering from several issues for some time, all of them looks the same but happening in different cases and different times.
the problem looks as sadden change in altitude when switching to mode or arriving to WP
I have placed a system (Sky walker 2014 - T tail frame) with pixhwak.

I have set it up according to all of the instructions in the ardupilot website.
I have install firmware 3.2.3 on it and load the parameters on the Aero-m located in mission planner.

Attached are the telemetry log files of the last flights:

  • Flight from 01.09.15 the problem accord in when switching to stabilized and to auto mode (30.2% of the log file). The next time accord when switching to auto mode (32.0% of the log file)

Flight from the 26.08.15 the problem accord when in auto mode (20.0% sadden climb in the altitude that led to stall. since that happened the plane did not enter to WP 3 and he was straggling to do so.
The problem appeared also in 25.9% of the log. Then I took over to manual and continue with manual mode.
it is really fostering since I have also established a system of Quad based on pixhwak with no issues at all (walk in the park……)/
Please can you advice what is wrong according to the log files.
My next option is to downgrade the system to APM 2.6 and see how it goes.
Thanks in advance for your kind help!! Im pretty lost here … :cry: :cry: :cry:

Had a look but can’t see anything to out of the ordinary so can’t help much. The RAW_IMU values seem a bit high almost as if there was a lot of vibration but they’re high even before takeoff without the motor running so don’t know what that is all about.
At 21.24% the plane pitches up to 30° but without increasing throttle which is also odd as they normally follow each other. Was it very hot with thermals perhaps?
I’d suggest turning on EKF_ENABLE as it does help with flying better.
BTW, why do you have a DO_CHANGE_SPEED command as your first waypoint?

Hi Graham,
thanks for the response.
the outside temperature was 31-35 degrees and we flue above dark brown land.
I can reassure you that the problem doses`t looks like thermals.
RE: why do you have a DO_CHANGE_SPEED command as your first waypoint?
I launch the plane by hand with out automatic take off. since that I left it after removing the auto takeoff.

BTW what dose the EKF_ENABLE do?


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