Flightradar24 is a global flight tracker that shows live air traffic from around the world. Flightradar24 combines data from several data sources including ADS-B, MLAT, satellite, and radar data. This positional data is aggregated with schedule and flight status data from airlines and airports to create a unique flight tracking experience on www.flightradar24.com and in the Flightradar24 app available for iOS and Android.
ADS-B
The primary technology that Flightradar24 use to receive flight information is called automatic dependent surveillance-broadcast (ADS-B).
- Automatic: the flight crew does not need to do anything to transmit the signal
- Dependent: the position data is dependent on the global navigation satellite systems (GNSS) being used by the transponder (GPS, GLONASS, Baidu, Galileo, etc)
- Surveillance: the technology is used a surveillance tool to know where aircraft are at any given time
- Broadcast: the aircraft is broadcasting the data to all receivers
What does Flightradar24 do with that data?
- The ADS-B transponder transmits a signal containing the position of the aircraft (and much more)
- ADS-B signal is picked up by a receiver connected to Flightradar24’s network
- Receiver sends data to Flightradar24
- Data is shown on www.flightradar24.com and in Flightradar24 apps
Introduced a few decades ago, ADS-B usage has grown steadily as various mandates requiring updated transponders have come into force in places like the United States, Canada, Europe, and Australia. ADS-B technology is the long-term air traffic management replacement for radar technologies, especially in areas with limited radar coverage, such as remote areas and oceanic airspace.
Flightradar24 has a network of more than 40,000 ADS-B ground based receivers around the world that receive flight information from aircraft with ADS-B transponders and send this information to our servers. Due to the high frequency used (1090 MHz) the coverage from each receiver is limited to about 250-450 km (150-250 miles) in all directions depending on location. The farther away from the receiver an aircraft is flying, the higher it must fly to be covered by the receiver. The distance limit makes it very difficult to get terrestrial ADS-B coverage over oceans.
ADS-B is a relatively new technology under development, which means that today it's rarely used by Air Traffic Control (ATC).
When mandatory, ADS-B will replace primary radar as the primary surveillance method used by ATC.
MLAT
In regions with coverage from several Flightradar24 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 Mode S transponder, it's possible to calculate the position of these aircraft. Four or more Flightradar24 receivers receiving signals from the same aircraft are needed for MLAT calculations. Because four or more receivers are needed to calculate the aircraft’s position, this can only be achieved at higher altitudes and in areas with many receivers.
Satellite
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.
North America Radar Data
In addition to ADS-B and MLAT, we also receive additional live data for flights in North America. This data is based on radar data (not just aircraft equipped with ADS-B transponders) and includes most scheduled and commercial air traffic in the US and Canadian airspace, as well as parts of the Atlantic and Pacific Oceans.
Australian Radar Data
Similar to North America, we receive additional radar data for air traffic in Australia. This data helps increase our coverage over Australia as well as parts of the Indian and Pacific Oceans.
Open Glider Network
Tracking data for gliders and other light aircraft comes from the Open Glider Network (OGN). It's a project that has the goal to provide a unified tracking platform for gliders, drones and other small aircraft. Currently focused on tracking aircraft equipped with FLARM and OGN trackers, but also accepting other data sources such as SPOT, FANET, PilotAware, etc.
Flarm is simpler version of ADS-B with a shorter range, primary used by smaller aircraft, in most cases gliders. The range of a Flarm receiver is between 20 and 100 km. Flarm receivers are often installed on small airports with a lot glider traffic to track the gliders around the airport.
Estimations
When an aircraft is flying out of coverage, Flightradar24 will estimate the position of the aircraft for up to 4 hours if the destination of the flight is known. For aircraft without a known destination, positions are estimated for up to 10 minutes. The position is calculated based on many different parameters and in most cases it's quite accurate, but for long flights the position can in worst cases be up to about 200 km (110 miles) off. You can customize how long aircraft out of coverage are estimated on the map under Settings. Estimations are displayed with a black trail on the map.
Blocking
Information about a small number of flights may be limited or blocked based on requests from owners or operators via third-party services, such as the FAA LADD. Some high profile aircraft, such as Air Force One are not displayed. Most other aircraft subject to restriction are shown as anonymized by aircraft type.
Coverage map
In areas where Flightradar24 normally has coverage, all major airports are marked with blue airport markers.
Flightradar24 relies on volunteers around the world for the majority of our coverage. Find out how you can contribute and host a receiver.
Please note that coverage and aircraft visibility is dependent on many parameters including aircraft type, aircraft transponder type, aircraft altitude and terrain, so coverage can be different for different aircraft, even on the same location. If an aircraft you are looking for is not visible on Flightradar24 it either does not have a compatible transponder or it's out of Flightradar24 coverage.
Please visit our FAQ to find answers to frequently asked questions about Flightradar24.
