Why European Airports Start With Different Letters Than American Ones

American airports use codes like LAX, JFK, and ORD. European airports use CDG, LHR, and FCO. But look closer and you’ll notice European codes often start with letters that seem unrelated to the airport name. Why does Paris Charles de Gaulle start with L (LFPG in the full code)? Why do all UK airports start with EG? The answer involves a global system developed nearly a century ago that divides the entire planet into alphabetically coded regions.

Two Systems Running in Parallel

The three-letter codes most travelers know (LAX, JFK, CDG) are IATA codes—created by the International Air Transport Association for ticketing and baggage handling. Airlines and passengers use these daily.

But aviation runs on a second system: four-letter ICAO codes used by pilots, air traffic control, and flight planning. The International Civil Aviation Organization assigns these codes, and they follow a geographic logic that IATA codes don’t.

ICAO’s four-letter structure: The first letter indicates global region. The second letter indicates country or sub-region. The final two letters identify the specific airport. This hierarchical system means any airport’s rough location is encoded in its identifier.

The Global Letter Map

ICAO divided the world into regions, each assigned a starting letter. This geographic encoding means knowing the first letter tells you approximately where an airport is located.

K – Contiguous United States: KLAX (Los Angeles), KJFK (Kennedy), KORD (O’Hare). Every airport in the lower 48 states starts with K, a legacy of radio call signs.

C – Canada: CYYZ (Toronto Pearson), CYVR (Vancouver). The C prefix immediately identifies Canadian airports.

E – Northern Europe: EGLL (London Heathrow), EHAM (Amsterdam Schiphol). The E region covers UK, Ireland, Netherlands, Belgium, and Scandinavia.

L – Southern Europe: LFPG (Paris CDG), LEMD (Madrid), LIRF (Rome Fiumicino). France, Spain, Italy, and other Mediterranean countries fall under L.

Other regional prefixes: U covers Russia and former Soviet states. Z covers China and North Korea. R covers Pacific Rim countries including Japan (RJ) and South Korea (RK). S covers South America. F covers much of Africa.

Why This System Exists

The geographic encoding serves practical purposes that pure airport naming wouldn’t accomplish.

Radio clarity: When pilots communicate with air traffic control across borders, the prefix immediately establishes geographic context. A flight plan to EGLL is obviously heading to the UK region regardless of whether the controller knows “Heathrow.”

Flight planning: Aviation charts, NOTAMs (Notices to Air Missions), and routing all use ICAO codes. The regional prefix helps pilots quickly categorize information by geographic relevance.

Systematic expansion: As new airports open, the system accommodates them logically. A new airport in France would get an LF prefix automatically, maintaining regional consistency.

The Second Letter: Country Codes

Within each region, the second letter typically indicates the specific country.

E region (Northern Europe):

EG – United Kingdom (EGLL London, EGBB Birmingham)
EH – Netherlands (EHAM Amsterdam)
EI – Ireland (EIDW Dublin)
EK – Denmark (EKCH Copenhagen)
EN – Norway (ENGM Oslo)
ES – Sweden (ESSA Stockholm)

L region (Southern Europe):

LF – France (LFPG Paris CDG, LFLL Lyon)
LE – Spain (LEMD Madrid, LEBL Barcelona)
LI – Italy (LIRF Rome, LIMC Milan Malpensa)
LP – Portugal (LPPT Lisbon)
LS – Switzerland (LSZH Zurich)

Why the US Uses K

The K prefix for US airports seems arbitrary until you understand its origin in radio history.

Radio call sign legacy: Before aviation codes existed, the International Radiotelegraph Convention of 1927 assigned letter prefixes to countries for radio stations. The United States received both W (for East Coast stations) and K (for West Coast stations).

Aviation adopted K: When aviation needed airport identifiers, the US adopted K as its national prefix. The familiar three-letter codes (LAX, JFK) are actually the last three characters of four-letter ICAO codes (KLAX, KJFK).

Why not W?: K was chosen for aviation while W remained primarily for broadcast stations. This historical split explains why American radio stations use W (East) and K (West) prefixes while all US airports use K.

The IATA Connection

The three-letter codes travelers use daily came from a different need: airline ticketing and baggage handling.

Origins in teletype: Airlines needed short codes for the limited teletype systems of the 1930s. Three characters balanced brevity with uniqueness across thousands of airports.

Legacy codes: Many early IATA codes derived from weather station or railroad codes that predated aviation. LAX referenced an older “LA” designation plus the X suffix common in the era.

No geographic logic: IATA codes don’t follow regional encoding. CDG, LHR, and FCO are memorable but don’t systematically indicate location. This is fine for ticketing but insufficient for aviation operations.

When the Systems Diverge

Sometimes IATA and ICAO codes bear no resemblance to each other.

Chicago O’Hare: IATA code ORD comes from the airport’s previous name, Orchard Field. ICAO code KORD adds the K prefix but otherwise matches.

London Heathrow: IATA code LHR uses the airport name. ICAO code EGLL uses the EG (UK) prefix plus LL, which doesn’t obviously relate to “Heathrow.”

Renamed airports: When airports change names, IATA codes sometimes change while ICAO codes remain stable, or vice versa, creating additional divergence.

Regional Exceptions and Oddities

The system isn’t perfectly consistent across all regions.

Pacific Islands: Small island nations often share prefixes in ways that don’t strictly follow country boundaries. The Pacific’s geography makes clean country-by-country assignment impractical.

Former Soviet States: The U prefix originally covered the entire USSR. After dissolution, new countries kept U prefixes but received different second letters, creating a patchwork that reflects historical rather than current boundaries.

Special territories: Colonial and dependent territories sometimes use parent country prefixes and sometimes receive their own. This inconsistency reflects aviation code development over decades of changing political geography.

Practical Implications for Travelers

Understanding the code systems helps travelers in several ways.

Reading flight tracking: Flight tracking services often display ICAO codes. Knowing prefixes helps identify route geography at a glance.

Aviation weather: METARs and TAFs (aviation weather reports) use ICAO codes. Travelers checking these resources need ICAO codes, not IATA codes.

Recognizing regions: When you see an unfamiliar code, the first letter reveals the region. VHHH might be unfamiliar, but the V prefix indicates South Asia—it’s Hong Kong.

The System’s Future

Nearly a century old, ICAO’s geographic encoding remains fundamental to aviation operations.

Expansion capacity: The four-letter system with geographic prefixes can accommodate many more airports than currently exist. No immediate pressure to replace the system exists.

Digital compatibility: Modern computer systems can handle any identifier format, but changing the system would require updating countless databases, documents, and training materials. The cost of change far exceeds any benefit.

Cultural persistence: Pilots, controllers, and aviation professionals worldwide know the system. This shared understanding provides value beyond mere airport identification.

The next time you see a European airport code that seems to bear no relation to the airport’s name, remember: that first letter places the airport on a global map. The system that seems arbitrary is actually remarkably systematic—a geographic encoding scheme that has organized world aviation for nearly a hundred years.