I have copter that goes up an down even in the calmest breeze. I was able to replicate this on the bench using a fan. In this setup the copter was not armed, nothing was moving, so no vibrations. But altitude changes (as displayed in Mission Planer) of 3 to 5 meters.
What could be the reason for this? Maybe a faulty pixhawk unit?
It’s very possible that it’s the barometer being affected by the wind. The flight controller should be in a case and also have a small bit of foam over the barometer. 3DR Pixhawks (in their original case) always have this but other manufacturers might have skipped this so might be worthwhile opening the case and see if there’s any foam. The barometer is normally a small silver rectangle near the edge of the board with two holes in the top.
A dataflash log might help get to the bottom of it if you’ve got one.
By the way, barometers can drift a few meters over time. So if I leave a baro on my desk for 5min it can certainly drift around a few meters.
Thanks very much for testing the beta release!