[JonnyS]

Some aircraft track very precisely on FlightRadar24, I can see movements along taxiways and precise circuit flying. Ours, however, tracks randomly and doesn't seem to be picked up below 2,000ft.

What factors might influence this? Aerial position? Transponder type?

[GrahamB]

ADS-B messages contain precise location data supplied by the GPS source. You therefore only need a minimum of one receiver to pick you up.

Mode S position is synthesised by FR24 using a technique called 'multilateration', which is dependent on:

- your transponder being swept by a radar head
- good line-of-sight visibility to a number of receivers, the more the merrier but even then it's not infallible

There are details on how it works on their site.

[JonnyS]

Thanks Graham, makes sense. We have a GTX330 but without the ES upgrade so it is Mode S only, which explains our coverage.

[Flying_john]

Does anyone know when RunwayHD will support the Garmin GDL90 data format that is sent from ADSB receivers ?