Geometric Altitude

[trappa-create]

Does Readsb Decodes Airborne position (w/GNSS Height) type 20-22?

I'm was playing with readsb and I noticed that I never receive directly the geometric altitude of aircraft but is always derived from altitude difference from baro.
Looking at the code it seems to be supported but with my testing Haven't seen one yet. Is this a bug or am I doing something wrong?

Thanks

[wiedehopf]

There might just be none of those messages in your area or from the aircraft above you.

If i recall correctly, those messages are only sent by certain transponders.