I have an interestering thing I am observing.
I spent a lot of time PID tuning and have my plane performing extremely well on some flights, but not on others.

It seems that about one in every 3 or 4 flights, the plane hunts back and forth along the waypoint line.

Normally, it closely tracks the waypoint line very accurately.
I am not changing any parameters between flights, its even the same flight plan in the latest case.


Here is the record of yesterdays flight, you can see it flys straight to each waypoint with very little tracking (mostly wind is affecting it).

Then today I flew the exact same mission and this was the result.


I cut short the second mission and returned home.

I only have APM logs if they are any use, but I'm wondering if this is something others have experienced and if there is something obvious I might be missing.




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Whats your APM hardware?


Do you have a magnetometer by chance? If so, try re-calibrating it again.


Are you using APM Planner as well? I've also noticed that weird values creep into my PID values (and waypoint values) sometimes, always refresh/read your configuration settings/waypoints before going on a flight so you know the plane has correct values.

Latest hardware versions and firmware as well. APM 1.4 and oilpan.

Not using a Mag.

Yes using APM planner.

I have the same trouble!!!!!!!!!! Why this happend????

Is a magnetometer neccessary to solve this issue??

I hope we can find the solution!


Yes, this still randomly happens for me.

When I get it, I simply land, reset the APM again and then takeoff and more often than not its fine. If not then I land again and try again.

It is very strange.

Franco, I thought at one point that it might have been caused by the airframe not being correctly level during the initialisation, check this as it will cause the same issue. I have subsequently discounted this theory.


Im facing the exact same problem. Have you found out the cause?

no, have ordered an APM2.

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