Hello, I did this because I noticed that the altitude of GPS is not stable. GPS coordinates are correct however.

They remain well within a radius of ten meters around the real point. But the altitude is completely crazy, it depends on the day, and even the moment of day. This is related to the position of satellites, I am in Europe, Is this the problem?.But, it's may be a problem for the stabilization of our plane in altitude. And increasingly it is not very accurate.

And with two I2C devices it works, cool.

What do you think of this approach?