Flightradar24's data comes from a network of volunteer-run ADS-B receivers, which explains why the coverage is so much better over the US and Europe where there

Flightradar24's data comes from a network of volunteer-run ADS-B receivers, which explains why the coverage is so much better over the US and Europe where there are lots of volunteers with their own ADS-B receivers than the rest of the world where there are not. Note for instance how coverage in Africa really only picks up again in South Africa around the major cities. ADS-B transponders are also not yet required on all aircraft outside of Europe so many planes don't have them and won't show up on this site. Some airline pilots will only activate certain modes of their ADS-B transponders in flight after take-off, particular those used to broadcast velocity and position, so it's possible that's what happened in your case. For all other cases the upload from the ADS-B receiver to the Flightradar24 site will be as real-time as is possible with standard internet infrastructure.