Altitude error in auto mode

Hi all ,

Arduplane 3.4
GPS ublox 7m

I set waypoint to altitude 500 m , when I change mode to auto plane flow the path correctly after 2 waypoint starting gain alt more than 500m the wind was good throttle is also good about 50% , but plane keep gain alt until it reach 900 m ,

Change to RTL it come back home and loiter , but still gain alt until battery get low and decent .
GPS was good and try again with change GPS , same problem ,

Test it in stab mode it’s very stab ,
Servo limits value is good by using another pixhawk ,

What’s the problem ?
What should i capture from the log file ?

Regards .

Check what level flight attitude looks like. If your plane is flying what is perceived as nose down and your airspeed is too high the plane will just keep climbing. The AP won’t point the nose down if your already at max down pitch.

My plane was flying level with 5ish degrees nose down and with a max down pitch of 10 degrees would cause the plane to over shoot altitude by 75 feet in turns. Once I got level flying attitude sorted and allowed 15 degrees of down pitch I was seeing no more than 5 feet of error during the flight.

Hi,Falcon ,
Have you solved your problem? Looking for your reply.

NOT YET
Maybe in weekend it will fly