Read on for the who, why, and how of flight numbers. You’ll be able to expand your travel knowledge and also sound incredibly in-the-know the next time you’re chatting with friends or strangers about your envious travel experiences.
Who Assigns Flight Numbers?
You’ll notice that every numerical flight number is preceded by a two-letter code. The letters represent the airline that is operating the flight and are assigned by the International Air Transport Association, or IATA (a trade association of the world’s airlines).
In some instances, these two letters are easy to decipher. For example, DL indicates Delta, AA indicates American Airlines and UA indicates United. But then there are some confusing ones, such as NK to represent Spirit Airlines and WN for Southwest. You can discover other code by searching the IATA database.
That’s easy enough, so what about the numerical part of the flight number? The airlines actually assign that value to their own flights. However, there isn’t a straightforward formula that they all follow and there are, of course, exceptions to the rules.
How Are the Numerals in Flight Numbers Created?
At the most basic level, flight numbers can only be up to 4 digits long. Airlines can choose any number from 1 to 9999. Due to superstition, they avoid using flight numbers 13, 666 and the like. Numbers that match aircraft models are also avoided to avoid confusion, such as 737 and 757.
The lower the flight number, the more important the route to that particular airline (such as flight number 1). The smaller flight numbers could indicate one of the airline’s original routes, a popular route, or one of its most-flown and highest-revenue routes.
Typically, flights flying north or east will be given an even number, while those going west or south will be given an odd number. This is one of those “rules” that is sometimes broken depending on a given airline’s internal rules and its scheduling system.
Additionally, airlines will retire flight numbers that represent a route that encountered a headline-producing incident. For example, American Airlines used flight number AA11 for its daily westward route from Boston to Los Angeles until the attacks of September 11, 2001. The flight number was then changed. The same is true of Malaysia Airlines flight 370, which disappeared en route from Kuala Lumpur to Beijing.
What happens to a flight number during a layover? In most cases, the number on your ticket will change because the route is different than the one that brought you to your layover destination in the first place. Especially if you’re switching from one airline carrier to another one, your flight number will not only change the numerical part, but also the two-letter code.
The last noteworthy fact is that an outbound flight number is generally one digit below the return flight. For example, Southwest’s WN 1 from DAL to HOU will increase to WN 2 when it returns HOU to DAL. And you guessed it — given that the flight numbers are so low, those are two of Southwest’s beloved routes.
Flight Number vs. Confirmation Number
A flight number is not the same as the confirmation number you receive when booking a reservation.
A confirmation number is typically an alphanumeric code used to identify your reservation and expedite the check-in process. You might use this code to check-in online or at the airport, or if you call into the airline’s customer service center, you’ll likely provide the code so they can quickly pull up your reservation.
Popular Numbers and Their Significance
Can you guess what popular annual event United Airline’s UA 500 from Indianapolis to San Francisco pays homage to? The Indy 500, of course!
Did you know that 7s are usually associated with “lucky” flight numbers, particularly those heading to Las Vegas? Here are some examples:
- JetBlue #777: Boston to Las Vegas
- Spirit Airlines #777: Ft Lauderdale to Vegas
- Frontier #777: Denver to Vegas
