Originally Posted by
El Bunto
No, as stated up-thread ADS-B emits BOTH barometric and GNSS ellipsoid altitude when both have onboard sources. Which for the 737-8 is true.
FR24 don't export one or the other in their downloadable CSV data, I haven't determined which, but both are visible in the web UI during interactive usage.
I can confirm that ADS-B data from Max 8 aircraft includes GNSS altitude, although strictly speaking it actually sends the difference between baro and geometric altitude, not the latter's absolute value, as it only has 7 bits available and maxes out at just over 3000' (127 x 25').
I'm confused about the FR24 reference, though. Their subscription plans grid does indeed state that Gold members get access to geometric height, but I've just replayed a selection of Max 8 flights (Air Canada, Icelandair and LOT) and for every one the GPS altitude on screen stays stubbornly on "N/A".
That said, I'm not sure why we're agonising over GNSS height as I haven't the faintest idea what height the ellipsoid is at Bole.
