A flight number is simply a unique identifier for a flight.

The International Transport Association (IATA) assigns flight numbers to all commercial flights – and all commercial flights have a flight number, while non-commercial flights typically don’t.

A private plane is normally identified by its registration number, and commercial cargo planes are identified by an ICAO call sign.

Some commercial airlines even use the same flight numbers in a code sharing agreement.

A flight number is identical for all passengers on a flight, while a ticket number is unique for every passenger on a flight. 

A flight number is a two-character and 1-to-4-digit number identifier of a flight. For example, AA2001 and BA2490 are both flight numbers.

Flight numbers are used by airlines, the FAA, and passengers to identify and keep track of flights. 

How Flight Numbers Are Generated

Flight numbers are primarily generated according to their travel direction.

Every U.S. Airline has its methodology for generating flight numbers, but most follow the following conventions: 

  • Two-digit flight numbers are usually for the most prestigious international routes, like New York to London. 
  • Three-digit flight numbers are used for both national and international flights. 
  • Four-digit flight numbers are usually domestic if they start with 1 or 2. 
  • Four-digit flight numbers are usually operated by a regional airline if they start with 3, 4, 5, 6, or 7. 
  • Four-digit flight numbers are usually codeshared flights if they start with an 8. For instance, a Delta flight operated by SkyWest. 
  • Four-digit flight numbers are special flights if they start with a 9. A rescue flight, for example. 

Eastbound & Northbound

North and eastbound flights are assigned even numbers. 

Outbound and Reverse Inbound Flights

Airlines use an odd number for an outbound flight.

Then they’ll use the next even number for its reverse inbound flight.

For example, a seven is followed by an 8. 

Short-Haul vs. Long-Haul Flights

Short-haul flights usually have longer codes than long-haul flights. 

Regional vs. Domestic Flights

Some airlines have separate number ranges for mainline and express flights.

For example, most U.S. mainline flights start from 1 to 2949, while flights from 2950 to 6099 are for regional flights.

The regional numbers are further broken down into blocks.

For example, Republic Airways numbers its flights from 4300 to 4699. 

Like regional flights, domestic flights also usually have longer codes. 

Private Flights

Private planes are usually identified by their registration number rather than a flight code.

For example, a Cessna 172 with the registration number O2345B would be identified as ‘Cessna October-two-three-four-beta.’ 

Cargo Flights

Commercial cargo planes usually have an ICAO call sign.

This sign has a three-letter designator, a verbal designator, and multiple special-purpose designations.

Sometimes cargo flight operators will be assigned a flight number, but not always. 

How to Find Your Flight Number

Your flight number is on your flight ticket and boarding pass.

You also receive an email with your booking information, including the flight number, when you book flight tickets. 

Not All Flights Have a Flight Number

All commercial flights have a unique flight number.

Private flights don’t have a flight number.

Cargo flights have flight numbers in some instances. 

Flight Numbers Can Be the Same Between Airlines

Flight numbers can be the same between airlines.

This is referred to as ‘codeshare.’

Two or more airlines enter into a codeshare agreement when they agree to market the same flight under the same flight number. 

When and Why Flight Numbers Change

Flight numbers can be changed for a couple of reasons:

  • Flight numbers are taken out of use due to a crash or serious accident.
  • Airlines also change flight numbers because of mergers or codeshare agreements.

It’s generally not common for airlines to regularly change flight numbers, though.

International aviation organizations limit the flight number system to only four digits, so there’s a finite number of flight numbers. 

Difference Between a Flight Number and a Ticket Number

A flight number identifies a flight. It is the same for all passengers on board a plane for a specific flight.

The ticket number identifies the individual passenger’s booking of the flight.

So a flight number identifies which flight a passenger will take, and their ticket number will confirm the passenger has bought a ticket for the flight.

In conclusion:

  • A flight number is a unique code, consisting of two letters, and up to four digits, that designates a particular flight.
  • The flight number system is mostly used for commercial airline flights. It helps passengers, the FAA, and airlines track flights.
  • While every airline in the United States has its own conventions for generating flight numbers, most follow a few conventions.
  • For example, prestigious international routes, like New York to London, usually only have two digits.
  • You can find your flight number printed on your ticket. You can also see it in the email you receive after booking your flight.

Ella Dunham, a Freelance Travel Journalist and Marketing Manager, boasts an impressive career spanning eight years in the travel and tourism sectors.

Honored as one of "30 Under 30" by TTG Media (the world’s very first weekly travel trade newspaper), a "Tour Operator Travel Guru" and "Legend Award" winner, Ella is also a Fellow of the Institute of Travel, a Member of the Association of Women Travel Executives, has completed over 250 travel modules, and hosts travel-focused segments on national radio shows where she provides insights on travel regulations and destinations.

Ella has visited over 40 countries (with 10 more planned this year).