How Flight Trackers Know Where Every Plane Is (ADS-B Explained)

Open any live flight map and you'll see thousands of little planes crawling across the world at once, each one tagged with a flight number, an altitude, a speed. It looks like magic, or like some vast radar dish watching the whole sky. The reality is more surprising and more elegant: the planes are telling on themselves.

On the LEV map, the Flights layer shows live air traffic gliding along its routes — and understanding how that works also explains the GPS jamming and ship-tracking layers nearby.

The trick is called ADS-B — and the plane does the work

The old picture of air-traffic tracking is a spinning radar dish bouncing signals off aircraft. That still exists, but the system powering most live maps is different and cleverer. It's called ADS-B — Automatic Dependent Surveillance–Broadcast — and the key word is broadcast.

Here's the whole idea in one breath: a modern aircraft figures out exactly where it is using GPS, then broadcasts that position — plus its altitude, speed, heading and identity — on an open radio frequency, roughly once a second. It does this automatically, constantly, without being asked. The plane isn't being found; it's announcing itself.

So a flight tracker doesn't need a giant radar. It needs listeners. A worldwide network of small, inexpensive ground receivers — a huge number of them run by hobbyist volunteers — picks up these broadcasts and pools them. Stitch together everything every receiver heard in the last second, and you have a live map of the sky. The genius of it is that the hard part (knowing the position) is done by each plane for free; the trackers just collect the chatter.

Why some planes are missing

Once you understand that tracking is listening, the gaps make perfect sense.

• Empty oceans and deserts. ADS-B is a line-of-sight radio signal with limited range. Over the mid-Atlantic or central Pacific there are no ground receivers to hear it, so coverage thins out. Satellites now plug many of these holes, but a plane in a true coverage gap simply goes quiet on the map.
• Aircraft that choose not to broadcast. Military aircraft and some private or sensitive flights restrict or switch off their broadcasts. They're flying; they're just not announcing.
• Older or unequipped aircraft. Not everything in the sky carries modern ADS-B.

A missing flight almost always means "no receiver could hear it here," not "it isn't flying." That's a coverage story, not a mystery.

It's legal, and it's nearly live

Because ADS-B is broadcast openly, unencrypted, in the clear, anyone with a cheap antenna can receive it — which is exactly why volunteer networks exist and why the data is freely available. What you see is real planes reporting real positions, usually only seconds old. (Some services delay certain flights slightly, but the underlying feed is live.)

Ships do the same thing — it's just called AIS

If the flights layer feels familiar to the ships on the map, that's no accident. Vessels run the maritime version: AIS (Automatic Identification System), broadcasting position, identity and heading over marine radio, gathered by coastal stations and satellites. The difference is pace and range — ships are slow and AIS reaches shorter distances, so coverage is thickest along coasts and busy shipping lanes, thinner in the open ocean.

This shared "everyone broadcasts their own position" design is what makes the GPS jamming layer possible at all: when those self-reported positions across a region suddenly stop making sense, that's the fingerprint of interference.

The fusion view: planes and weather

Where LEV goes beyond a plain flight tracker is by putting that traffic on the same map as the weather steering it. Turn on Flights with the wind layer and you can see why eastbound flights ride the jet stream while westbound ones detour around it; add Storm Warnings or Radar and you can watch traffic bend around a line of storms in real time. The planes broadcast where they are — the weather explains why they're going that way.

The bottom line

Live flight maps aren't watching the sky with radar; they're listening to planes that constantly announce themselves via ADS-B, gathered by a global mesh of small receivers. Once you know that, the empty oceans, the missing military jets, and the near-live timing all stop being mysterious — and the same broadcast trick quietly powers the ships and the jamming map too.