RTL crashed my plane!

This was the first flight of my bixler with the 2.5 APM.  It was a bit blustery for being so early, I did find the stabilization fighting me for control for most of the flight.

I am just not sure what happened.  Without warning my plane switched into RTL mode and quickly the motor shut off and it headed strait into the ground.

I was able to get telemetry logs from the ground station, I just don't know where to look to find failure.

It seems to me that a failsafe kicked in and RTL switched on.  My questions to the internet are why did it turn on and why didn't it fly safely to launch?

I had a good GPS lock, everything before the launch seemed a-ok.

logs attached.

2012-11-04 12-12-35.tlog

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  • One detail that may have impact.  A friend of mine who was watching the ground station answered her ringing cell phone moments before the crash.  as far as I can tell, this is the only thing that might have caused interference.

  • Hi,

    I also had uncommanded switching into RTL in at least one flight. The plane ended up in a tree in a lawyer's garden, trying to fly through a hill, hmm :) Before the crash, it did the same a few times enroute, only to change back into auto a little later.

    The cause of the problem is undetermined. There is very little jitter in the RC mode signal and I checked that the mode PWMs had enough margin to both sides. I did not use the PPM encoder on the APM2, as the RC Rx has a single PPM output anyway.

    I have looked through the code without finding any apparent bugs (there).



  • Calibrate your RC input
    It is highly recommended that you switch into either Stabilize or Fly By Wire mode and observe the behavior of the control surfaces. They should move to return the plane to level when you pitch or roll it. If it isn't rock solid, you can tune the gains by following the instructions here.

    Unless you have tuned your configuration parameters for your airframe it IS NOT recommended that you take off in any mode other than Manual.

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