Three names for the same flight
The flight number is what is printed on your ticket: a two-character airline code followed by up to four digits, such as AA1 or BA117. The two-character code is the airline's IATA designator. The same physical flight may carry several flight numbers at once through codeshares, so a Lufthansa-operated flight might be sold as LH, UA and AC numbers.
The callsign is what the crew says to air traffic control, and it uses the airline's three-letter ICAO designator plus the flight number: AAL1 for American 1, BAW117 for British Airways 117, DAL for Delta, UAL for United, SWA for Southwest. Some airlines also use a spoken name that differs from the letters ("Speedbird" for BAW, "Cactus" was US Airways). Callsigns are what ADS-B transmits, which is why trackers display them.
The registration (tail number) identifies the specific aircraft, not the flight: N12345 in the United States, G-EUUU in the UK, D-AIMA in Germany, 9V-SKA in Singapore. Each airframe also has a fixed 24-bit hex code, such as A1B2C3, that its transponder broadcasts; trackers use this as the permanent key for an aircraft even if the callsign changes.
The tracker on our home page accepts any of the three: search a flight number, a callsign or a registration and it resolves the rest.
Where tracking data comes from
Position, altitude, speed and callsign come from ADS-B, a broadcast most airliners transmit continuously and that networks of volunteer receivers collect; we explain it in How ADS-B flight tracking works. Schedule data, the aircraft type and registration assigned to a flight, gate times and status come from airline and airport systems via a flight-data provider. Trackers stitch the two together, which is why a flight can show "scheduled" with no position (it has not transmitted yet) or a position with no schedule (a charter, ferry or private flight).
Reading the status fields
- Scheduled times are the published timetable.
- Estimated times are the airline's or airport's current prediction, which moves as the day unfolds.
- Actual departure is normally gate pushback ("off-block"), and actual arrival is gate arrival ("on-block"); some sources show runway take-off and landing times instead, which differ by ten to thirty minutes of taxiing. Our flight pages note which they are showing.
- Delay is measured against the scheduled time; an arrival within 15 minutes counts as on time by the usual definition, which we cover in What counts as an on-time flight.
Finding out which aircraft will fly your flight
Airlines assign specific aircraft to flights only a day or so in advance, and the assignment can change right up to departure. The reliable moment is when the aircraft is actually flying: once airborne the registration appears in the ADS-B feed and on the flight page. Looking up the same flight number on previous days shows which registrations usually operate it, and for the flights we follow the history table does exactly that. Seat maps for the type then tell you what the cabin will be like; our seat maps cover the major carriers.
Tracking tips
- Search by flight number when you want the schedule and status; search by registration when you want to follow a particular aircraft wherever it goes.
- Use the date picker to pull up a past day's flight; history on open ADS-B networks is limited, so recent days work best.
- A flight that disappears mid-ocean has not vanished; it has flown out of receiver range. Satellite ADS-B fills those gaps for commercial trackers, but open networks rely on ground receivers.
- Codeshare numbers may not resolve on trackers that only know the operating carrier; try the operating airline's own number if a search comes up empty.