Poor alt. hold is auto mode

Im flying a QAV500 quadcopter for a couple months now with the apm2.5 on 2.8.1 update. I've had a lot of success I think with this product, and every flight is a learning experience. Most of my problems I've found are operator error because I'm new to all this PID tuning stuff and fpv. I think I've got my copter tuned in pretty well except for one thing. When I try auto missions the copter never climbs to the alt I programmed, and between wp's it slowly loses altitude and will decend into the ground if wp's are too far apart. When it reach's a wp's it bounces back up to 10 foot or so and then continues on its way slowly descending. If I put it in alt hold mode it stays nicely and I can fly around a few feet off the ground or 30 feet off the ground, doesn't matter it holds alt. within a meter or so. Loiter mode also holds alttitude well. So what am I not doing correctly when planning a mission? I have a feeling it must be a setting in the planner somewhere, but I'm still new to all this and am not sure the consequences of all the changes I can make.Qav500Amp 2.5 on 2.8.1 firmwareSonar (more than three inches from other electronics)18amp plush escNx4008 motorsTurnigy 4s 4000 lipoSpectrum dx6i currently but normally hitech a9 radioStinger 250mw 5.8ghzYellowjacket pro diversity 5.8Any recommendations are appreciated

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  • Well now I have no señor data in terminal or MP. It allows me to arm the board now, it wasn't for a while. I've had enough and ordered a Naza With gps today. And when I start my octo build this winter I'll prolly get the woo kong. I really want the autonomous flying, but I need something proven. Ill revisit this board down the road cause i really like the concept.
    Thanks for the comments guys.
  •  Perhaps your barometer is getting faked  by higher pressure  when travelling at higher horizontal velocity.  A test method to see if this is happening would be to set Alt Hold mode  and fly manually at high speed  and see if altitude droops  during transit and bobs up on hover. Also, you could  try a mission with WP's closer together and with  WP speed ( ie. WP_SPEED_MAX) set  lower  to  say 3-4 m/s.

     I have a APM 2.0 which hides the baro under the daughter board  but I think a lot of APM2.5  users are putting cotton pads on their barometers to avoid errors due to turbulence.

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