How are GPD altitude calculated on FR24?

[JKF]

Hello,

I'm currently doing a small project, where I'm reading raw ADS-B data from a RadarCape looking for the positions messages containing GNSS heights (not barometric). These kind of messages have a special subtype (tc:20-22), where a position with barometric height is 9-19. I'm currently not receiving any messages with GNSS heights to my disappointment.

So, I was wondering how FR24 calculates GPS heights of aircrafts, or atleast what this data is based of?

[Gaelan]

Hi JKF,

Unfortunately the question you've asked would reveal publicly a little too much about the inner workings of Flightradar24. The information you're looking for should be available in ADS-B documentation externally to Flightradar24 and we wish you all the best your small project!

Hello,

I'm currently doing a small project, where I'm reading raw ADS-B data from a RadarCape looking for the positions messages containing GNSS heights (not barometric). These kind of messages have a special subtype (tc:20-22), where a position with barometric height is 9-19. I'm currently not receiving any messages with GNSS heights to my disappointment.

So, I was wondering how FR24 calculates GPS heights of aircrafts, or atleast what this data is based of?