ICAO Airport Code Validator

ICAO codes: the regulatory backbone of international aviation

The International Civil Aviation Organization (ICAO) is a specialized agency of the United Nations created by the Chicago Convention of 1944 and headquartered in Montreal. Its 193 member states harmonize the technical rules of air navigation: airworthiness standards, ATC phraseology, runway markings, NOTAM format, and — most relevant here — the global system of location indicators used by every flight plan, weather report and ATC clearance.

Unlike IATA codes (commercial, optimized for tickets), ICAO codes are designed for the operational and regulatory side of aviation. They appear on flight plans filed with the AIS, in METAR/TAF weather reports, in NOTAMs, in radar labels, in the database that Mode S transponders broadcast, and in publications like ICAO Doc 7910 (Location Indicators) and Doc 8643 (Aircraft Type Designators).

Airport ICAO codes: 4 letters with a geographic prefix

Airport ICAO codes are 4 uppercase letters. The first one or two letters encode the country or region: SB Brazil, SC Chile, SP Peru, SU Uruguay, SK Colombia, SA Argentina (further split by region), K contiguous United States (KJFK, KLAX, KORD), EG United Kingdom (EGLL Heathrow), EH Netherlands (EHAM Schiphol), ED Germany (EDDF Frankfurt), LF France (LFPG CDG), RJ Japan (RJTT Haneda).

Examples for Brazilian airports, all prefixed SB: SBGR Guarulhos, SBRJ Santos Dumont, SBGL Galeão, SBBR Brasília, SBSP Congonhas, SBCT Curitiba, SBPA Porto Alegre, SBFZ Fortaleza, SBRF Recife, SBSV Salvador, SBBE Belém, SBMN Manaus, SBKP Viracopos. Smaller and untowered aerodromes typically have an ICAO code (or a regional SI/SD/SS/SN/SW code in Brazil) even when no IATA code is assigned.

Country prefix map you'll see most often

• K___: contiguous USA. KATL Atlanta, KMIA Miami, KSEA Seattle.
• C___: Canada. CYYZ Toronto Pearson, CYVR Vancouver.
• EG__: United Kingdom. EGLL Heathrow, EGKK Gatwick, EGCC Manchester.
• LE__ Spain, LP__ Portugal, LI__ Italy, LF__ France, ED__ Germany, LO__ Austria, LS__ Switzerland.
• OM__ UAE (OMDB Dubai), OE__ Saudi Arabia, VH__ Hong Kong, ZB__/ZS__/ZG__ China, RK__ South Korea, YS__ Australia.

Airline ICAO callsigns: 3 letters that fly the radio

Airline ICAO codes are 3 letters and pair with a spoken radio callsign: TAM LATAM Brasil (callsign "TAM"), AAL American Airlines ("American"), BAW British Airways ("Speedbird"), UAL United ("United"), DLH Lufthansa ("Lufthansa"), UAE Emirates ("Emirates"), QFA Qantas ("Qantas"), SIA Singapore ("Singapore"), GLO Gol ("Gol Transporte"), AZU Azul ("Azul"). ATC calls flights by the callsign + flight number, not by the IATA designator.

Aircraft type designators (ICAO Doc 8643)

ICAO type designators are typically 2–4 alphanumeric characters: B738 Boeing 737-800, B77W 777-300ER, A320 Airbus A320, A359 A350-900, E195 Embraer 195, AT72 ATR 72. These differ from IATA aircraft codes and are mandatory in field 9 of a flight plan.

Where ICAO codes live in the operational stack

• Flight plans (ICAO FPL): every field — origin, destination, alternates, route waypoints — uses ICAO designators.
• METAR/TAF weather: a METAR starts with the airport ICAO (METAR SBGR 281200Z 09008KT ...).
• NOTAMs: notices addressed by location indicator (A1234/26 NOTAMN Q) SBBS/QMRLC/IV/NBO/A/...).
• ATIS: automated terminal information service broadcasts include the airport ICAO at the start of the message.
• Mode S transponder: every aircraft is assigned a unique 24-bit ICAO aircraft address (six hex digits) broadcast by ADS-B. OpenSky Network, ADS-B Exchange and FlightRadar24 index flights by this 24-bit ICAO.
• TCAS collision avoidance uses Mode S/ICAO addresses to interrogate nearby traffic.

ICAO vs IATA: when to use which

If the code is on a boarding pass, baggage tag, ticket or itinerary, it is IATA. If it is on a flight plan, METAR, NOTAM, radar label or aviation chart, it is ICAO. Airport: ICAO = 4 chars (SBGR), IATA = 3 chars (GRU). Airline: ICAO = 3-letter callsign (TAM), IATA = 2 chars (LA). One frequent gotcha is that many small Brazilian aerodromes have an ICAO but no IATA at all — those airports cannot be booked commercially but can absolutely host a private flight plan.

Brazilian regulator chain: ANAC, DECEA and ICAO

In Brazil, ICAO standards are translated to local rules by the ANAC (civil aviation regulator) and operationalized by DECEA (Departamento de Controle do Espaço Aéreo, part of the Air Force). DECEA publishes the AIP Brasil, manages flight plan filing through the CINDACTA centers, and assigns ICAO codes inside the SB/SD/SI/SN/SS/SW blocks. ANAC handles certification of operators, airworthiness and consumer regulation (RBAC 121, 135, 91, etc.).

FAQ

Is an ICAO airport code always 4 letters?

Yes. ICAO Doc 7910 mandates exactly 4 uppercase letters for airport location indicators. No digits, no punctuation, no length variants.

Do general aviation pilots really need ICAO codes?

Yes. Any IFR flight plan and any cross-border flight requires ICAO codes for origin, destination, alternates and waypoints. Even VFR pilots use them when filing a plan or reading METAR/TAF for their route.

What is the Brazilian prefix in ICAO codes?

The main prefix is SB for the largest international and domestic airports. Smaller aerodromes use additional regional blocks: SD (São Paulo regional), SI (São Paulo interior), SN (Nordeste), SS (Sul), SW (Centro-Oeste/Norte).

Where can I download the full list of ICAO codes?

The authoritative source is ICAO Doc 7910, which is published commercially. Free alternatives include the OpenFlights dataset, OurAirports.com (CC0 public domain) and Wikipedia's per-country location indicator articles.

Why does a small airport have an ICAO code but no IATA code?

Because ICAO assigns location indicators to any aerodrome that may appear in a flight plan or aeronautical chart, including untowered fields with zero commercial service. IATA only allocates codes to airports relevant to the commercial airline industry.