Understanding Automatic Dependent Surveillance-Broadcast technology and how it powers modern flight tracking.
Automatic Dependent Surveillance-Broadcast (ADS-B) is a surveillance technology that has revolutionized air traffic control and flight tracking. Unlike traditional radar, which sends out radio pulses and interprets the reflections, ADS-B relies on aircraft actively broadcasting their position, altitude, speed, and identification. This "dependent" nature means the system depends on the aircraft's own GPS receiver and transponder to provide accurate data.
ADS-B has two components: ADS-B Out, which is the broadcast from the aircraft, and ADS-B In, which allows aircraft to receive broadcasts from other aircraft and ground stations. Since January 2020, the FAA has required all aircraft operating in most US controlled airspace to be equipped with ADS-B Out. Similar mandates exist in Europe, Australia, and other regions.
Every aircraft equipped with ADS-B Out broadcasts a signal on 1090 MHz (Mode S Extended Squitter) containing its ICAO 24-bit address, position (latitude and longitude), barometric altitude, ground speed, heading, and vertical rate. These transmissions occur approximately twice per second, providing near-continuous position updates. Some lighter aircraft use a second frequency, 978 MHz (UAT), primarily in the United States.
ADS-B signals are received by ground-based receivers, which can be as simple as a USB TV tuner dongle connected to a Raspberry Pi with a small antenna. Thousands of aviation enthusiasts around the world operate such receivers, feeding data to aggregation platforms like PlaneTrack.ai. This crowd-sourced network of receivers provides global coverage that rivals or exceeds traditional radar networks.
PlaneTrack.ai aggregates data from multiple receiver networks and processes it in real-time. Raw ADS-B messages are decoded, deduplicated, and correlated with flight plan databases to add airline name, origin, destination, and aircraft type information. The resulting enriched data is displayed on the live map with position updates every 15 seconds, providing users with a comprehensive view of global air traffic.
Traditional primary radar detects aircraft by bouncing radio waves off them, requiring no cooperation from the aircraft. Secondary surveillance radar (SSR) queries aircraft transponders for additional information. While radar has served aviation well for decades, it has limitations: expensive ground infrastructure, limited range over oceans and remote areas, and lower position accuracy compared to GPS-based systems.
ADS-B overcomes many of these limitations. It provides precise GPS-based positioning (within about 30 meters), works anywhere with GPS coverage (including over oceans), requires minimal ground infrastructure, and updates faster than radar. The crowd-sourced nature of ADS-B reception means that coverage can be extended simply by volunteers installing inexpensive receivers in underserved areas.
While ADS-B has transformed flight tracking, it has limitations. Aircraft can turn off their transponders, making them invisible to ADS-B receivers (this is sometimes done by military aircraft for operational security). Coverage gaps exist in remote areas without receiver coverage, particularly over the deep ocean, polar regions, and parts of central Africa and Asia.
Additionally, ADS-B signals are unencrypted and unauthenticated, which raises concerns about signal spoofing and privacy. Some aircraft owners, particularly private jet operators, have requested that their flights be blocked from public tracking platforms. PlaneTrack.ai respects these blocking requests while still providing comprehensive coverage of commercial and general aviation traffic.
One of the great things about ADS-B is that anyone can set up their own receiver. All you need is a Raspberry Pi (or similar single-board computer), an RTL-SDR USB dongle (around $25), and a 1090 MHz antenna. Free software like dump1090 or readsb decodes the signals, and you can feed your data to PlaneTrack.ai and other aggregation networks. A basic setup on a windowsill can receive aircraft within a 100-200 nautical mile radius, while a rooftop-mounted antenna with a filtered amplifier can achieve ranges exceeding 250 nautical miles.
Contributing your ADS-B data to PlaneTrack.ai helps improve coverage and ensures that flight tracking remains accurate and comprehensive. In return, contributors often receive premium features and access to enhanced data feeds. Join our community of receivers to help build the world's most complete flight tracking network.
ADS-B stands for Automatic Dependent Surveillance-Broadcast. It is a system where aircraft broadcast their GPS position, altitude, speed, and identity. This data is received by ground stations and used for air traffic control and flight tracking platforms like PlaneTrack.ai.
In the US, ADS-B Out has been mandatory in most controlled airspace since January 2020. Europe requires it for aircraft above a certain weight. However, some small aircraft, military aircraft, and aircraft in less regulated airspace may not broadcast ADS-B signals.
Yes. A basic ADS-B receiver costs about $50-100 and consists of a Raspberry Pi, an RTL-SDR USB dongle, and a 1090 MHz antenna. Free software decodes the signals, and you can feed data to PlaneTrack.ai to help improve global coverage.