How Does Flight Tracking Work? (Complete Guide)
Flight tracking works by collecting radio signals that aircraft already transmit, working out where each aircraft is, and drawing it on a map. Most of the live positions you see online come from ADS-B, supported by multilateration, radar and, over oceans, satellites.
The four sources of position data
ADS-B. The aircraft works out its position from GPS and broadcasts it about once or twice a second on 1090 MHz, together with altitude, speed, heading and callsign. Anyone with a receiver can decode it. Read what is ADS-B.
MLAT. Some aircraft do not broadcast a position but do send transponder signals. If several ground receivers hear the same signal, the tiny differences in arrival time reveal the aircraft’s location. See what is MLAT.
Radar. Air traffic control uses primary radar (radio echoes) and secondary radar (transponder replies). Most public trackers do not get radar feeds directly. Learn the difference in primary vs secondary radar.
Satellite ADS-B. Satellites can receive the same ADS-B signals over oceans, deserts and mountains where ground receivers do not reach. See satellite ADS-B.
From signal to map
- An aircraft transmits a message.
- A receiver on the ground decodes it and sends it over the internet to a network such as the OpenSky Network.
- The network combines messages from many receivers and keeps the latest position of each aircraft.
- A website like this one fetches that data, filters it, and draws aircraft on a map.
Each step adds delay, which is why flight tracking data is delayed by seconds to minutes.
What a tracker can and cannot tell you
A tracker can tell you where an aircraft is, how high, how fast and where it is heading. It cannot, on its own, tell you the airline’s schedule, the gate, or whether a flight is late, because those come from airline systems. We explain this on our methodology page.
Identifiers you will meet
- Callsign vs flight number: the radio name of a flight is not always the number on your ticket.
- ICAO 24-bit address: a unique code that identifies each aircraft’s transponder.
- Squawk codes: four-digit codes assigned by air traffic control.
Coverage in Pakistan
Coverage depends on receivers. It is strong near some cities and weak in mountains and remote areas. Pakistan’s position between Europe, the Gulf and Asia means many aircraft cross its airspace; see Pakistan airspace explained. You can help fill gaps by becoming a feeder.
Accuracy and limits
Read how accurate flight tracking is and why flights disappear from the map.
General information only, not legal or safety advice. Details change; check with your airline and the relevant authority. See our editorial policy.