There is a reason for everything in the aviation industry.
And the numbers and letters you see on your boarding pass are no random combination.
Every airline uses a specific system to ascribe letters and numbers to every flight.
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The letter component of the flight number is fairly straightforward: They represent the carrier.
For example, Delta uses DL, American Airlines is AA, and United is UA.
Every single flight number must be from 1 to 9999.
(There are some exceptions to the rule.)
Airlines typically assign the return flight number as one digit higher than the outbound flight.
For example, JetBlue has a flight from JFK to LAX that’sJBU523.
When it returns to JFK, the flight number isJBU524.
Generally, the lower the flight number, the more important that route is to the airline.
Delta operatesDL1, a route between New York’s JFK and London Heathrow.
The very important flight number likely relates to the airline’s history.
Delta’s very first international destination wasLondon in 1978.
(Although, back then, the flight operated from Atlanta.)
There are a few flight numbers you are unlikely to ever see.
Flights won’t ever have a number like 737 to avoid confusion with the model of aircraft.
And, due solely to superstition, airlines won’t operate flight 13 or flight 666.
