Person booking a flight on their phone

Here's What Your Flight Number Actually Means

By Hilary I. Lebow


Flight numbers might seem random, but the codes inform airport personnel which carrier you're taking, how important the flight is to the airline, and what direction you're heading.
Flight numbers are generated using a combination of computer algorithms and human preference, a process that's careful to avoid duplicates, retired numbers, or confusing codes.
There are some universal patterns across airline codes. The first part of the code is usually two letters to represent the airline, such as DL for Delta or NK for Spirit Airlines.
After the letters, flights are assigned a number between 1 and 9999. The lower the number, the more prestigious, lucrative, or historic the flight is.
Odd numbers are typically for flights that go south or west, while even numbers go north or east. A flight number with a one-digit difference refers to outbound and return flights.
There are certain sequences that aren't used often, like flight 13 or flight 666. Airlines also retire flight numbers out of respect after tragic incidents like terrorist attacks.
Some sequences are used for a lighthearted spin. Some airlines use flight number 777 for flights to Las Vegas, and United Airlines uses the lucky number 8 for flights to China.