How Airlines Name Flights and Assign Flight Numbers

A flight number is the airline’s two-character code followed by a number of up to four digits. Airlines assign numbers by pattern, such as by direction, region or time of day, and reuse them each day the flight runs.

What a flight number means

PK 300 means: PK, the IATA code of Pakistan International Airlines, and 300, the airline’s own number for that service. The same number usually describes the same route and time on different days. If the route or time changes, the airline may change the number.

Patterns airlines use

• Direction: many airlines use odd numbers for one direction and even numbers for the opposite one.
• Region: series of numbers can be reserved for a region or route group.
• Time of day: repeat daily flights on the same route may get consecutive numbers.

Each airline decides its own system, so do not assume a pattern.

Same number, different days

The same number can fly a different route on different days, or two flights can share a number for a stopover (a “direct” flight with a stop). Check the route on your ticket.

Callsigns

On the radio the flight number is combined with the airline’s three-letter ICAO code, as in callsign vs flight number. Codeshare flights carry several numbers; see codeshare.

Finding yours

See how to find your flight number.

General information only, not legal or safety advice. Details change; check with your airline and the relevant authority. See our editorial policy.