Guide
How to read a flight number
BAW117, SHT7J, RYR8GK, RRR2145. What the letters mean, why the callsign on a tracker rarely matches the number on your boarding pass, and how to tell a military flight from a holiday charter at a glance.
The shape of it
Three letters for the airline, then a number that is theirs to choose.
The first three characters are an ICAO airline designator: BAW for British Airways, RYR for Ryanair, DLH for Lufthansa, UAE for Emirates. These are not the two-letter codes on a ticket. BA is the IATA code you book with; BAW is what the aeroplane transmits.
That is the single most common source of confusion. A boarding pass says BA117; the aircraft broadcasts BAW117; a tracker may show either depending on what it has looked up.
The rest is the flight number, and airlines use it more loosely than passengers expect. Numbers are often reused, occasionally with a letter suffix when a flight is repeated or repositioned, and a delayed aircraft may fly under a different number entirely.
Which is why the callsign is a useful label and a poor identity. The registration painted on the tail, and the 24-bit address behind it, are the things that identify an aeroplane.
Patterns worth knowing
What the callsign tells you before you look anything up.
Shuttle and subsidiary codes
SHT is BA's domestic shuttle, so SHT7J is a British Airways flight even though it does not say BAW. Airlines commonly have several designators for different parts of the operation, which is why an aircraft in a familiar livery can carry an unfamiliar prefix.
Military
RRR is the Royal Air Force, RCH is US Air Mobility Command, NATO speaks for itself. Military callsigns often look like plain words on the radio and appear as three letters plus digits on a tracker.
Ferry, test and positioning
Unusual suffixes and round numbers often mean an aircraft is not carrying passengers: repositioning empty, going for maintenance, or on a test flight after work. Manufacturers use their own designators for factory aircraft.
No callsign at all
Light aircraft frequently transmit their registration instead, so G-OSRT is both the tail number and the callsign. Some transmit nothing beyond position and identity, which is normal and not suspicious.
Registrations
The tail number tells you where an aircraft is registered, not where it is going.
Every country has a prefix. G- is the United Kingdom, EI- Ireland, D- Germany, F- France, N the United States, VH- Australia, A6- the United Arab Emirates. So G-STBH is British-registered, whoever is operating it and wherever it happens to be flying.
The registration stays with the airframe for its working life unless it changes owner or country, which makes it the right thing to keep a record against. A flight number lasts one flight.
Leases muddy it. An aircraft in one airline's colours may be registered elsewhere and flown on behalf of a third: a Ryanair flight can be operated by Ryanair Sun on a Polish registration. None of that is visible from the ground, and all of it is visible on a tracker.
Questions
The ones we are asked.
- Why does the tracker show a different flight number to my ticket?
- Your ticket uses the two-letter IATA code, the aircraft transmits the three-letter ICAO one. BA117 and BAW117 are the same flight.
- What does RRR mean on a flight tracker?
- Royal Air Force. RCH is US Air Mobility Command. Military transport aircraft frequently broadcast normally and appear like any other flight.
- What is the difference between a callsign and a registration?
- The callsign belongs to the flight and changes daily. The registration, the letters painted on the tail, belongs to the airframe for years. Only the registration identifies a specific aeroplane.
- Why do some aircraft show a registration as their callsign?
- Light aircraft and private flights usually transmit their registration, because there is no flight number to transmit. It is normal.
- Can I tell where an aircraft is from by its registration?
- You can tell where it is registered, which is often but not always where the operator is based. Leasing and cross-border operations make the two diverge more often than people expect.
The product this comes from
Airborne draws what is overhead, on a screen in your room.
The airline's own livery on that airframe, with the route and the height beside it, redrawn every thirty seconds. Five views on one screen. If it cannot identify something, the frame stays empty rather than guessing.