15 Airport Code Facts That Will Impress Your Seatmate

Airport codes are more than random letters. Each three-character combination has a story—historical accidents, linguistic quirks, or deliberate choices that made sense at the time. Here are fifteen facts about airport codes that reveal the hidden logic behind those letters on your boarding pass.

1. The X Factor

Codes like LAX, PDX, and PHX include an “X” that seems arbitrary. In the early days of aviation, airports often inherited two-letter codes from the National Weather Service. When aviation needed three letters, “X” was frequently added as a placeholder with no meaning—just a way to extend the code.

2. Canada’s Y Obsession

Almost every Canadian airport starts with “Y”—YYZ (Toronto), YVR (Vancouver), YUL (Montreal). This dates to the 1930s when Canada assigned “Y” to denote airports with co-located weather stations (“Yes, we have a weather station”). The pattern persisted long after the original reason became irrelevant.

3. The ORD Mystery

Chicago O’Hare uses ORD, which seems to have nothing to do with Chicago or O’Hare. The code comes from “Orchard Field,” the airfield’s original name when it was a Douglas aircraft manufacturing plant during World War II. The airport was renamed for Medal of Honor recipient Edward O’Hare, but the code stayed.

4. Australia’s Systematic Approach

Australian airports often use codes that spell airport names: MEL (Melbourne), SYD (Sydney), PER (Perth), ADL (Adelaide). This systematic approach makes Australian codes among the most logical in the world—a refreshing exception to historical accidents.

5. The JFK Exception

When New York’s Idlewild Airport was renamed to honor President Kennedy in 1963, the code changed from IDL to JFK—one of the rare cases where a name change prompted a code change. The significance of Kennedy’s assassination created political will to accept the disruption.

6. IATA vs. ICAO

Two parallel code systems exist. IATA’s three-letter codes (LAX, JFK, LHR) appear on tickets and baggage. ICAO’s four-letter codes (KLAX, KJFK, EGLL) are used by pilots and air traffic control. The systems developed independently and serve different purposes.

7. The K is for Contiguous

Most U.S. airports’ ICAO codes start with “K”—KJFK, KORD, KLAX. Hawaii uses “PH” (for Pacific/Honolulu area), and Alaska uses “PA” (for Pacific/Alaska). The “K” designates the contiguous 48 states in international aviation protocols.

8. Some Cities Have Multiple Codes

NYC, WAS, and LON are city codes representing all airports in metropolitan areas. NYC includes JFK, LGA, and EWR. WAS includes DCA, IAD, and BWI. LON covers five London airports. These help travel agents handle “I just need to get to London” requests.

9. The Heathrow Story

London Heathrow uses LHR—”London Heathrow” with the vowels removed. Many British airports follow similar patterns: MAN (Manchester), BHX (Birmingham—the X added because BHM was taken), EDI (Edinburgh).

10. Double Letters Mean Isolation

When a country’s airports use repeated letters—like YYZ (Toronto), ZZV (Zanesville), or XXL—it often indicates limited aviation activity when codes were assigned. With fewer airports to differentiate, repeating letters wasn’t problematic.

11. Old Names Die Hard

Washington Dulles (IAD) and Washington Reagan (DCA) reveal history. IAD meant “International Airport, Dulles.” DCA meant “District of Columbia Airport.” Name changes to “Washington Dulles International” and “Ronald Reagan Washington National” didn’t change codes that referenced original names.

12. Some Codes Are Warnings

SIN (Singapore) and DIE (Aruba—now AUA) seemed problematic. DIE was changed; SIN remains because Singapore decided the code wasn’t actually negative. BUM (Butler, Missouri) survives presumably because the airport is too small for anyone to complain.

13. The QXYZ Shortage

IATA reserves certain letters for non-airport uses: Q for internal airline codes, X-Y-Z patterns for special purposes. This reduces the available pool from 17,576 possible combinations, though plenty remain.

14. Ghost Codes Persist

When airports close, their codes are typically retired rather than reassigned. This prevents confusion with historical records—an airport that closed in 1970 shouldn’t share a code with one that opened in 2020.

15. Some Codes Were Chosen Deliberately

Modern airports sometimes lobby for meaningful codes. When Austin’s new airport opened, it could have received any available code—but AUS made sense and was available. Not all codes are historical accidents; some reflect intentional branding.

The Common Thread

Airport codes accumulate meaning through decades of use. Whatever their origin—weather stations, military facilities, creative abbreviation, or pure accident—they become embedded in systems that resist change. The cost of updating codes across global aviation infrastructure ensures that today’s puzzling letters will puzzle travelers for generations to come.

Next time you’re waiting to board, glance at your destination code and consider what history it might contain. That three-letter combination connected your booking to baggage handling to flight planning to air traffic control—a tiny standardized key that makes global aviation function.