Abnormal altitude loss in althol when flying forward

Dear all,
I know that this problem has been discussed several times, both here and and DIY forum, but I am wondering if someone could help diagnosing this.
I have 3 different quadcopter and all of them suffer from altitude loss when in althold mode or auto.
I tryed several solution and now I am flying with a dome over pixhawk and the inlet of the baro sensor, has been routed (via a silicon tube) to the GPS antenna mast

so far, none of this solution solve or even mitigate the effect…
What sound really strange is that it has bee always reported as a behaviour with high pitch angle and high speed, but in my case the speed is very low … down to 3m/s
The result is the impossibility to fly in halthold and even worst in auto mission mode…

Any help or suggestion is highly appreciated!!!

Not enough information in the logs. You switched many times to different modes and what I could see the copter was following the set Altitude with no issues.

I fly all the time with my Pixhawk in the open with nothing around it and have seen no issue with Altitude hold. What I have seen is if I fly full forward the copter will start to loose Altitude as it flies but this is indicated in the logs.

Not seeing this in your logs.

You need to build a Mission with several waypoints that are far apart so we can see what your talking about. Set the altitude at 20 or 30 meters so it will take some time before it hits the ground.


ok, thanks for this !:slight_smile:
I will try to set up a mission, but it’s a little bit scarry because altitude loss is huge … :scream:

Then it could be that you are creating a vacuum that makes the barometer think it is rising causing it to fall. The logs show a flat barometer for most of your flight. We should see a spike at the end when it stops moving. Not seeing this.