FlightGlobe — glossary

Name: FlightGlobe live feed
Creator: FlightGlobe

Plain-language definitions of the terms used across FlightGlobe (OpenSky Network + adsb.lol (ODbL 1.0)).

The signal

ADS-B: Automatic Dependent Surveillance–Broadcast: the system in which an aircraft derives its own position from GPS and broadcasts it (with altitude, velocity and identity) on 1090 MHz for any receiver to hear. The backbone of public flight tracking.
1090 MHz: The radio frequency on which most ADS-B and transponder messages are transmitted. Ground stations tune to it to receive the broadcasts that flight trackers render.
State vector: The bundled snapshot of an aircraft at a moment in time: position (latitude/longitude), barometric and geometric altitude, ground speed, track/heading and vertical rate. The unit a tracker draws on the map.
Ground station: A receiver — antenna plus software-defined radio — that picks up 1090 MHz broadcasts from aircraft within radio range. Networks pool thousands of them; each only hears roughly to its local horizon.

Callsign: The name a flight goes by on the radio and on the map, often an airline code plus a number (e.g. “BAW123”). It belongs to the flight, not the airframe, and can change from trip to trip.
ICAO 24-bit address: A unique hexadecimal code burned into an aircraft’s transponder — one airframe, one address. Unlike a callsign it stays fixed, so it reliably identifies a specific aircraft.
Registration (tail number): The visible alphanumeric identifier painted on an aircraft’s fuselage (e.g. “N12345”). It maps one-to-one to the airframe and to its ICAO address while the registration is held.
Squawk code: A four-digit transponder code, usually assigned by controllers. Three are reserved emergencies worldwide: 7500 (unlawful interference/hijack), 7600 (radio failure) and 7700 (general emergency).

Flight level: Barometric altitude on a standard pressure setting, expressed in hundreds of feet — FL350 is about 35,000 ft. Used above a transition altitude so aircraft share a common reference and stay vertically separated.
Ground speed: How fast an aircraft moves over the earth’s surface, reported here in metres per second (m/s). It differs from airspeed because of wind: tailwinds raise it, headwinds lower it.
Track vs. heading: Track is the direction an aircraft actually travels over the ground; heading is where its nose points. Crosswinds push the two apart, so a plane can fly slightly sideways relative to its path.
Vertical rate: How fast an aircraft is climbing or descending. Read with altitude it reveals the phase of flight — departure climb, level cruise or arrival descent.