I’ve read that ADS-B reports both barometric (pressure altimeter) and geometric (usually from GPS) altitudes, so my question is how do we know which type of altitude is being reported? I am using the GetLastTrack function in FlightXML2.0.
Altitudes from FXML (and shown on the main website etc) are typically uncorrected pressure altitudes.
We do collect GNSS altitude from ADS-B but it’s not plumbed all the way through the server-side processing at the moment.
If you’re collecting ADS-B data locally, Skyview/Skyaware shows both altitude when available.