ADS-B – the aircraft reports its own position
With ADS-B (Automatic Dependent Surveillance – Broadcast) an aircraft determines its position by GPS and broadcasts it several times a second on 1090 MHz. Each message includes the aircraft’s 24-bit ICAO address (shown on the map as “ICAO 24-bit”, e.g. 48AE23), position and altitude, ground speed, track and vertical rate, the flight’s call sign (e.g. LOT281) and the transponder code (squawk).
The signal is unencrypted and anyone with a suitable antenna can receive it. In Europe, ADS-B has been mandatory since 2020 for aircraft with a maximum take-off mass above 5.7 tonnes or a cruising speed above 250 knots, so virtually every passenger and cargo aircraft appears on the map.
How the data reaches the map
ADS-B only reaches as far as the horizon – a few hundred kilometres for an aircraft at cruising altitude. Covering a whole country takes many receivers, and most are run at home by aviation enthusiasts with a rooftop antenna, a cheap SDR receiver and a small computer.
FlyRadar uses data from adsb.lol, an open community network of such receivers (licensed under ODbL). Our server fetches every aircraft over Poland and its surroundings in one request about every 15 seconds and shares it with all users; other regions load when you zoom in and refresh about once a minute. Between updates we move each icon along its track at its speed. When you click an aircraft we also load its flight path since take-off for the map and the altitude chart.
Routes come from the adsbdb.com and adsb.lol databases, and photos from planespotters.net, always credited. The aircraft doesn’t transmit its route – it is matched to the call sign, so for charter flights it can be wrong.
MLAT – when no position is broadcast
Older transponders (Mode S without ADS-B) send messages without coordinates. Their position can still be calculated by multilateration (MLAT): if at least four time-synchronised stations receive the same signal, the differences in arrival time reveal where it came from. MLAT positions are less precise and update less often – the flight panel shows this under “Position source”.
Why some aircraft are missing
- No ADS-B transmitter – light aircraft, gliders, balloons and some helicopters.
- Military aviation – often flies with ADS-B switched off or only uses it in certain situations.
- No coverage – low to the ground, in mountains or far out at sea the signal may not reach any receiver, so a plane can “disappear” just before landing. Estimated positions are shown semi-transparent.
- Blocked data – some private and business aircraft owners ask for their identifiers to be hidden.
Altitude and speed
Aircraft report pressure altitude, measured against the standard pressure of 1013.25 hPa. At cruising level every aircraft uses the same reference, which keeps separation safe even as the weather changes; the true height above sea level can differ by a few hundred metres. Flight level FL350 is 35,000 feet, about 10,670 m.
Speed is ground speed. At cruising altitude a strong westerly wind (the jet stream) often blows, so an eastbound aircraft can exceed 1,000 km/h while the same type flying west is 150–200 km/h slower.
Squawk codes 7500, 7600, 7700
A squawk is a four-digit transponder code assigned by air traffic control. A few codes have a fixed meaning:
| Code | Meaning | What it usually is |
|---|---|---|
| 7700 | Emergency | Most often a medical emergency, a technical issue or a precautionary return. The crew declares it to get priority. |
| 7600 | Radio failure | The crew cannot talk to air traffic control and continues under set procedures. |
| 7500 | Unlawful interference | Reserved for hijacking. It appears very rarely, often as a keying error. |
| 7000 | VFR flight | The standard European code for visual flights without an individual code. |
Aircraft squawking 7500, 7600 or 7700 are highlighted in the flight panel and in the “Emergency” filter.
Flight number, call sign and registration
Your ticket shows the IATA flight number, e.g. LO281. On the radio the aircraft uses its ICAO call sign, usually with a three-letter airline code, e.g. LOT281. They don’t always match – Ryanair and Wizz Air use call signs with letters (e.g. RYR5CL) to avoid confusion. Our search accepts both.
The registration is the aircraft’s “number plate”. Its prefix shows the country: G – United Kingdom, SP – Poland, D – Germany, PH – Netherlands, UR – Ukraine, EI – Ireland, 9H – Malta (where part of the Ryanair and Wizz Air fleets is registered).
Build your own ADS-B receiver
An ADS-B station is cheap: a USB receiver (RTL-SDR), an antenna tuned to 1090 MHz, a small computer such as a Raspberry Pi and free software like readsb. The antenna should see as much of the horizon as possible; in a good spot it picks up aircraft 200–400 km away. You can share the data with open networks such as adsb.lol and improve coverage in your area.
The radar is for information only and must not be used for navigation or travel planning – check arrival and departure times with your airline or airport.