A unique alphanumeric identifier assigned to an airport by the International Air Transport Association (IATA) or the International Civil Aviation Organization (ICAO), used globally in flight bookings, baggage handling, air traffic control, and travel itineraries.
An airport code is a standardized identifier assigned to an airport for use in aviation operations, ticketing, and travel logistics. Two parallel systems exist: IATA's three-letter codes (used in commercial travel) and ICAO's four-letter codes (used in air traffic control and flight operations).
IATA has assigned approximately 11,300 three-letter location codes out of 17,576 possible combinations, with 40 to 50 new codes issued annually [1].
The three-letter system replaced a two-letter National Weather Service system in the late 1940s when aviation growth exceeded the 676 possible two-letter combinations [1].
Navan uses IATA airport codes throughout its booking platform to match travelers with correct departure and arrival airports, route corporate travel policies by airport, and generate accurate itinerary records.
IATA codes are considered permanent once assigned. Changes are extremely rare and require strong justification, typically involving air safety concerns [1].
What is an Airport Code?
An airport code is a unique alphanumeric identifier that distinguishes one airport from every other airport in the global aviation network. The code appears on boarding passes, baggage tags, flight schedules, GDS booking systems, and travel itineraries. Two separate coding systems operate in parallel, each serving a different purpose.
IATA codes are three-letter identifiers managed by the International Air Transport Association under Resolution 763. These are the codes travelers encounter most frequently: JFK for John F. Kennedy International Airport, LHR for London Heathrow, NRT for Narita International Airport. IATA codes are used in ticketing, baggage handling, passenger name records, and commercial booking systems.
ICAO codes are four-letter identifiers assigned by the International Civil Aviation Organization. The same airports above become KJFK, EGLL, and RJAA under the ICAO system. These codes are used by pilots, air traffic controllers, and airline operations teams for flight planning, airspace management, and safety communications.
For business travelers and travel managers, IATA codes are the relevant system. They appear on every booking confirmation, expense report, and travel policy document. Understanding how they work helps travel managers configure location-based policies and ensures employees search for the correct airport when booking through a managed travel platform.
How Are IATA Airport Codes Assigned?
IATA assigns codes following a structured process that balances clarity with the constraints of a finite namespace.
Primary rule: reflect the location name. When a new airport requests a code, IATA prioritizes combinations that match the city or airport name. Denver International Airport received DEN. Boise Airport received BOI. This intuitive mapping helps travelers recognize airports from their codes alone.
City-name conflicts require creativity. When the obvious three-letter abbreviation is already taken (there are only 17,576 possible combinations), airports receive codes drawn from alternative spellings, historical names, or the airport's own name rather than the city. Chicago O'Hare is ORD because the airport was originally called Orchard Field. Montreal's main airport is YUL, following the Canadian convention where "Y" prefixes designate airports, combined with the city's historical code.
Multi-airport cities get distinct codes. Cities with multiple airports each receive separate codes. New York has JFK, LGA (LaGuardia), and EWR (Newark). London has LHR (Heathrow), LGW (Gatwick), STN (Stansted), and LTN (Luton). For corporate travel policies, this distinction matters because different airports may fall under different pricing zones, ground transportation costs, and preferred carrier routes.
Codes are permanent. Once assigned, IATA codes almost never change. The most cited exception is Washington Dulles, which was changed from DIA to IAD to avoid confusion with nearby Reagan National (DCA). This permanence means some codes carry historical artifacts. Peking's old romanization survives in PEK (Beijing Capital International Airport), even though the city has been officially called Beijing for decades.
IATA vs. ICAO Codes
Feature
IATA Code
ICAO Code
Length
3 letters
4 letters
Assigned by
International Air Transport Association
International Civil Aviation Organization
Primary use
Commercial aviation: ticketing, baggage, booking systems
Flight operations: air traffic control, flight planning, weather reporting
Who sees it
Travelers, travel managers, booking platforms
Pilots, air traffic controllers, airline dispatchers
Example (JFK)
JFK
KJFK
Example (Heathrow)
LHR
EGLL
Regional prefix
None (codes are globally unique without geographic structure)
First letter indicates region (K = contiguous U.S., E = Northern Europe, R = East Asia)
The ICAO system's regional prefix structure makes it more systematic but less intuitive for non-aviation users. EGLL tells a pilot the airport is in the UK (EG = United Kingdom) and specifically London (LL), but a traveler wouldn't recognize it the way they recognize LHR.
Why Airport Codes Matter for Corporate Travel Management
Airport codes serve three practical functions in corporate T&E programs beyond simple identification.
Location-based travel policies. Companies set different spending limits for different airports. A night at a hotel near SFO (San Francisco) costs significantly more than near OMA (Omaha). Travel management platforms use airport codes to apply location-specific per diem rates, hotel caps, and ground transportation allowances automatically.
Route-based reporting. When finance teams analyze travel spending by route, airport code pairs (known as city pairs in industry terminology) reveal patterns. If the JFK-LAX route accounts for 25% of annual airfare spending, the company can negotiate a corporate discount on that specific route. Without standardized airport codes, this analysis requires manual location matching.
Multi-airport city routing. For cities with multiple airports, the choice of airport affects total trip cost, ground transportation time, and traveler experience. A meeting in Manhattan is a 60-minute taxi from JFK but 20 minutes from LGA. A meeting in the City of London is 15 minutes from LCY (London City Airport) but 60 minutes from LHR. Travel policies that specify preferred airports by meeting location reduce time waste and ground transportation costs.
Notable Airport Codes and Their Origins
Several well-known codes illustrate the system's historical quirks and assignment patterns.
ORD (Chicago O'Hare): Named after Orchard Field, the airport's original name when it was a military airfield. The name changed to honor Navy lieutenant Edward "Butch" O'Hare in 1949, but the code stuck.
YYZ (Toronto Pearson): Canada adopted the convention of prefixing airport codes with "Y." The remaining letters (YZ) were the two-letter radio station identifier for the Malton (now Mississauga) area where Pearson is located.
PEK (Beijing Capital): Based on Peking, the Wade-Giles romanization of the city's name that was standard in Western aviation when the code was assigned. When Beijing Daxing International opened in 2019, it received PKX.
LAX (Los Angeles International): Originally coded as LA under the two-letter system. When the shift to three letters occurred in 1947, "X" was added as a placeholder, a common practice at the time.
FRA (Frankfurt): A straightforward city-name abbreviation. Frankfurt's code is often cited as the ideal example of how the system should work.
These examples illustrate why codes sometimes seem arbitrary. They aren't. They reflect the specific moment in aviation history when each airport entered the global system.
How to Use Airport Codes in Travel Booking
When booking through a managed travel platform, entering the correct airport code ensures the search returns flights for the right location. Common sources of confusion include cities with multiple airports (searching "London" returns results for six airports), airports whose codes don't match the current city name, and airports that share similar codes (DCA for Washington Reagan vs. DEN for Denver).
For frequent flyer program management, airport codes also determine which partner lounges are accessible during connections, which ground transportation options appear in the booking flow, and which per diem rates apply to the destination.
Related Terms
Itinerary: The travel document that displays airport codes for each flight segment, connecting departure and arrival points in sequence.
City Pairs: The origin-destination airport code combination used to analyze route-level travel spending and negotiate corporate discounts.
PNR (Passenger Name Record): The booking record that stores airport codes alongside traveler details, flight times, and ticket information.
An airport code is a unique identifier assigned to each airport worldwide. The most common type is the IATA three-letter code (like JFK, LHR, or SFO), used in ticketing, baggage handling, and booking systems. ICAO assigns separate four-letter codes (like KJFK) used by pilots and air traffic controllers.
Codes reflect the airport's name or the city's name at the time of assignment, and codes are considered permanent. Chicago O'Hare is ORD because it was originally Orchard Field. Beijing is PEK based on the old romanization "Peking." Historical codes persist even after airports or cities are renamed.
The three-letter system allows 17,576 possible combinations. Approximately 11,300 codes are currently assigned, with 40 to 50 new codes issued annually. The system is increasingly crowded, which means new airports often receive less intuitive code assignments.
IATA codes are three letters used in commercial aviation (booking, ticketing, baggage). ICAO codes are four letters used in flight operations (air traffic control, flight planning). Navan uses IATA codes throughout its booking platform to match travelers with the correct airports and apply location-based travel policies automatically.
Extremely rarely. IATA considers assigned codes permanent. Changes require strong justification, typically involving air safety. The most cited example is Washington Dulles changing from DIA to IAD to avoid confusion with nearby Reagan National (DCA).
Major metropolitan areas with multiple commercial airports each receive separate IATA codes. New York has JFK, LGA, and EWR. London has LHR, LGW, STN, LTN, LCY, and SEN. For corporate travel, the choice between airports affects ground transportation time, cost, and carrier availability.
A Passenger Name Record (PNR) is a digital file stored by airlines with a passenger's travel booking details, including itinerary, personal info, and flight history.
A city pair is the origin and destination combination on a flight route, expressed as a pair of airport or city codes. In corporate travel management, city pair data helps organizations analyze travel patterns, negotiate airline contracts, and optimize travel spend.
