Flightradar24 is a flight tracker that shows live air traffic from around the world. We combine data from several data sources including ADS-B, MLAT, and radar data. The ADS-B, MLAT, and radar data are aggregated together with schedule and flight status data from airlines and airports to create a unique flight tracking experience on www.flightradar24.com and in Flightradar24 apps.
The primary technology that Flightradar24 uses to receive flight information is called automatic dependent surveillance-broadcast (ADS-B). The ADS-B technology itself is best explained by the image to the right.
Aircraft get their location from a GPS navigation source (satellite).
The ADS-B transponder on aircraft transmits a signal containing the location (and much more).
The ADS-B signal is picked up by a receiver connected to Flightradar24.
A receiver feeds data to Flightradar24.
Data is shown on www.flightradar24.com and in the Flightradar24 apps.
In some regions with coverage from several FR24-receivers we also calculate positions of non-ADS-B equipped aircraft with the help of Multilateration (MLAT), by using a method known as Time Difference of Arrival (TDOA). By measuring the time it takes to receive the signal from aircraft with an older ModeS-transponder, it's possible to calculate the position of these aircraft. Four FR24-receivers or more, receiving signals from the same aircraft, are needed to make MLAT work. MLAT coverage can only be achieved above about 3,000-10,000 feet as the probability that four or more receivers can receive the transponder signal increases with increased altitude.
Satellite-based flight tracking is the latest step in our quest for global ADS-B coverage. Satellites equipped with ADS-B receivers collect data from aircraft outside our terrestrial ADS-B network’s coverage area and send that data to the Flightradar24 network. Satellite-based ADS-B data available on Flightradar24 comes from multiple providers. As the number of satellites supplying data and their location are dynamic, satellite coverage varies. Generally, satellite-based ADS-B increases coverage of flights over the ocean where ground-based reception is not possible. Only aircraft equipped with an ADS-B transponder may be tracked via satellite.
In addition to the flight tracking methods mentioned above, we also use other sources including North American Radar Data, Open Glider Network, and estimations.
You can learn more about how flight tracking works on our “How it works” page here.