Aviation explained: How flight tracking websites know the plane's location?

Obtaining flight tracking data has been made possible because of Automatic dependent surveillance-broadcast technology, or ADS-B technology used in modern aircraft.

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For a lot of people flying from one place to another without knowing where they can be a very daunting task. This is where the flight tracking websites come to the rescue. These tracking websites work to find the exact location of the flight.

Flight-tracking technology has been revolutionising the aviation industry. Generally, the data for tracking the planes used to be obtained with the airports as the source of information, but the accuracy of this data used to be a bit off.

By using new methods, now the data is directly obtained from the aircraft. This has been made possible because of Automatic dependent surveillance-broadcast technology, or ADS-B technology used in modern aircraft.

The ADS-B technology is a complicated, relatively new system used for tracking flights. For better understanding, here we have explained how plane tracking sites work to find the exact location of an aircraft.

What is ADS-B technology?

ADS-B technology is a sophisticated system earlier designed for pilots to keep a track of the whole traffic with greater precision. It also enables the pilots to be updated about the most terrain and weather updates along with other information.

The other information transmitted by the tech includes speed, altitude and aircraft identification. It also includes the airspace information or other ADS-B aircraft reports.

How does ADS-B work?

It works with transmitting signals through a satellite-based network. The signal is sourced from the ADS-B transponder on the aircraft containing the location information, along with other details. The signal is then picked by a receiver providing the information needed.

The technology uses a high frequency to transmit the signals, hence limiting the reach of information. This limited reach sometimes becomes a hindrance in getting the exact location of the aircraft in the far end of the ocean.

Due to the limited reach, the height of the flight needs to increase in proportion with the distance from the receiver to ensure that the signal is properly received.

What if a plane is out of ADS-B range?

If the destination of the flight is known, the position of an aircraft flying out of coverage can be calculated for up to 2 hours. The position is predicted for up to 10 minutes for aircraft with no known destination.

The position is estimated using a variety of characteristics and is usually relatively precise, but for long flights, the position can be as much as 100 kilometres (55 miles) off. There is a parameter in the options for how long you want to see estimated aircraft on the map.

How are flights without ADS-B tracked?

The non-ADS-B flights are tracked using a radar tracking system, or the positions can be calculated using Multilateration (MLAT). The MLAT system uses a method called Time Difference of Arrival (TDOA). However, MLAT coverage can only be reached above around 3,000-10,000 feet.

It is feasible to calculate the position of aircraft using a ModeS-transponder by monitoring the time it takes to receive the signal. To make MLAT operate, four or more FR24-receivers must be receiving signals from the same aircraft. As the possibility of four or more receivers receiving the transponder signal increases with altitude.