If you've ever wondered how a website can show thousands of planes moving in real time, the answer is ADS-B — Automatic Dependent Surveillance–Broadcast. It's the backbone of every modern live flight tracker, including Aether Track.
What ADS-B actually is
ADS-B is a system where aircraft broadcast their own position, altitude, speed, heading, and identity roughly twice per second on the 1090 MHz radio frequency. The signal is unencrypted and anyone with a cheap software-defined radio (around $20) can pick it up.
- Automatic — the aircraft sends data on its own, without being interrogated.
- Dependent — the data depends on onboard GPS.
- Surveillance — it's used by air traffic control to see where planes are.
- Broadcast — it's sent in the open for anyone to receive.
How the data gets to the map
Volunteer-run receivers on rooftops around the world pick up ADS-B messages from any aircraft within radio line-of-sight (typically 200–400 km depending on terrain). Those receivers feed into aggregator networks. Live flight trackers query the aggregators, decode the messages, and plot each aircraft on a map.
Why coverage isn't perfect
- Oceans and remote areas — no ground receivers, no signal. Some satellites (Aireon) help, but consumer trackers rarely have access.
- Military and sensitive flights — often filtered out or transmit with limited data.
- Older aircraft — small general aviation planes may use Mode S (less data) or nothing at all.
What you see on Aether Track
Each aircraft icon is a real ADS-B transmission decoded within the last few seconds. The trail behind it comes from previous positions. Click any aircraft for callsign, registration, origin/destination (when available), altitude, ground speed, and vertical rate — straight from the aircraft's own broadcast.