Originally Posted by
27/09
Not necessarily so. Plenty of aircraft I know of that don't have ADSB show up on FR24
Correct. Many non ADS-B aircraft will show up more or less correctly on FR24 and FlightAware thanks to MLAT interpretation of mode S data. These are attributed by FR24 as MLAT. However, there is a ongoing problem with certain FR24 feeders causing MLAT data calculated outside of FR24 to be fed back to FR24 by an ADS-B feeder. These are not labelled as MLAT and therefore give the impression the plane has ADS-B. Quite often the tracks from these are wildly inaccurate.