Every moving icon on the map above is a real aircraft, plotted from data the aircraft sends out itself. This page explains where that data comes from, why its accuracy varies from place to place, and how to get useful answers out of a flight tracker. That might mean finding out when your mother lands, or which jet just flew over your house.
On this page
What is a flight radar?
A “flight radar” is a website or app that shows aircraft positions on a map in near real time. Click a plane and you usually see its flight number, airline, aircraft type, route, altitude, speed and estimated arrival time. Services such as Flightradar24 and AirNav Radar (formerly RadarBox) also mix in airline schedules, airport departure boards, weather layers and photos of the aircraft.
The name is misleading, though. Most of these services do not use radar. Radar sends out radio pulses and listens for echoes bouncing off an object. Air traffic control and the military still rely on it, partly because it also detects aircraft that send no signal at all. Consumer flight trackers work the other way around: they listen for signals the aircraft broadcasts on its own.
How flight tracking really works
A tracker combines several data sources. That is why one plane on the map can be precise to a few meters while another is only an educated guess.
ADS-B: the aircraft reports its own position
Most airliners and many smaller aircraft carry an ADS-B (Automatic Dependent Surveillance–Broadcast) transponder. The aircraft works out its position by satellite navigation and broadcasts it about once a second, along with its altitude, speed, heading and a unique identifier. The signal is unencrypted, so anyone with a small antenna and a receiver can pick it up from up to a few hundred kilometers away. Flight tracking companies collect these messages from thousands of volunteer-run ground receivers. Flightradar24 says its network has more than 50,000.
Why almost every airliner shows up
ADS-B became widespread because regulators required it. In the United States, aircraft flying in most controlled airspace have needed ADS-B Out since January 1, 2020. Europe phased in a similar rule for larger and faster aircraft between 2020 and 2023. Many other regions have comparable rules, so nearly every commercial flight now broadcasts its position.
MLAT for older transponders
Some aircraft have transponders that send a signal without a position. If at least four ground receivers hear the same signal, the tracker can calculate where the aircraft is from the tiny differences in arrival time. This is called multilateration (MLAT). It needs a dense receiver network, so it mostly works over land and at higher altitudes.
Satellite ADS-B over oceans and remote areas
Ground receivers can't cover the middle of the Atlantic or the Pacific. ADS-B receivers carried on satellites fill that gap, so you can follow long-haul flights across oceans, although updates there can be less frequent than over land.
Other feeds and estimated positions
In some countries, trackers also use data from air traffic control radar, usually with a delay. When a plane leaves coverage completely, the tracker may keep moving it along its expected route and mark the position as estimated. These estimated positions can drift from reality, so treat them as a guide, not a fix.
| Source | How the position is found | Typical strengths and limits |
|---|---|---|
| ADS-B (ground) | Aircraft broadcasts its own satellite-based position | Very accurate; needs a receiver within range |
| MLAT | Timing differences across 4+ receivers | Works for older transponders; mostly at higher altitudes over well-covered land |
| Satellite ADS-B | ADS-B received by satellites | Covers oceans and remote areas; ADS-B-equipped aircraft only |
| Radar feeds | Air traffic control radar data | Only in some countries, often delayed |
| Estimates | Calculated from last known track and route | Fills gaps; can be off |
Who uses a flight tracker, and why
- People picking someone up. A live track tells you whether the plane left on time and how far out it is, so you can leave for the airport at the right moment instead of guessing from the timetable.
- Travelers. If your incoming aircraft is still sitting at another airport, your own flight will probably leave late. You often see this on a tracker before the departure board changes. For gate changes and cancellations, the airline is still the official source. See our guide on how to check flight status.
- Plane spotters. Spotters use trackers to see when a rare aircraft, special livery or new type is about to land, and which runway is in use.
- Drone pilots. A tracker gives a quick picture of nearby traffic before a flight. It is no substitute for official airspace apps and authorizations, because not every aircraft shows up, especially low-flying helicopters and light aircraft.
- Aviation fans and the curious. Some people just enjoy watching the morning rush of transatlantic arrivals, following a storm diversion, or finding out what the jet overhead is and where it's going.
How to use the live map above
- Move and zoom. Drag the map to pan, and scroll or pinch to zoom. Zooming in on your area makes individual aircraft easier to pick out.
- Click an aircraft. A panel opens with the flight's details and its track so far.
- Look for a specific flight. Use the search in the full apps for a flight number or airport. Our step-by-step guide explains how, plus the usual traps such as codeshare flight numbers.
- Don't panic if a plane vanishes. It has usually flown out of receiver coverage or descended below it. The FAQ covers this and other common questions.
Flight tracker guides
The two best-known flight trackers each have their own strengths. Our guides explain what the free versions show, what the paid plans add, and how to get the most out of the apps.
Flightradar24The largest consumer flight tracker: data sources, plans, symbols and app tips.
RadarBox (AirNav Radar)How the tracker formerly called RadarBox works, and what its app offers.
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Frequently asked questions
Is the live map on this page in real time?
Close to it. ADS-B positions usually appear within seconds, but data from radar feeds and satellites can lag, and positions outside coverage may be estimated. For anything time-critical, such as a gate change, rely on the airline.
Why is a plane I can see in the sky not on the map?
It may be outside receiver coverage or flying too low for nearby receivers. It may have an older transponder in an area without enough receivers for MLAT, or its owner may have asked for it to be hidden. Military aircraft often don't broadcast ADS-B at all.
Do I need an account to track a flight?
No. Basic live tracking works without signing up on the major trackers. A free account mainly lets you save favorites. History beyond a few days and advanced filters usually need a paid plan.
Can a flight tracker tell me if my flight is delayed?
It shows the scheduled and estimated times, and whether the aircraft for your flight has arrived from its previous trip. That is a good early warning, but the airline remains the official source for delays and cancellations.
Is it legal to track flights?
In most countries, yes. ADS-B signals are broadcast openly so that other aircraft and controllers can receive them, and trackers display this public information. Some aircraft owners can limit what is shown through programs such as the FAA's LADD.