ICAO Code

Definition

An ICAO code is a unique four-letter alphanumeric airport or location identifier assigned by the International Civil Aviation Organization (ICAO). These codes are used in flight planning, air traffic control, weather reporting, and international aviation operations. Unlike IATA codes (used for passengers and baggage), ICAO codes serve operational and regulatory purposes.

Purpose

  • Provide a global standard for identifying aerodromes, FIRs, and ATC units
  • Enable accurate and unambiguous routing in flight plans
  • Used in ATIS, METAR/TAF, NOTAMs, and airspace coordination
  • Integrate with navigation databases, charts, and radio communication

ICAO vs. IATA Codes

FeatureICAO CodeIATA Code
Format4 letters3 letters
UsageATC, flight plans, charts, weatherTickets, reservations, baggage
ExampleEDDF (Frankfurt/Main)FRA
AuthorityICAO (global)IATA (airline trade body)
ScopeAirports, FIRs, ATC units, navaidsPassenger-facing airport codes only

ICAO Code Structure

ICAO codes are regionally structured:

  • First letter: Geographic region
  • Second letter: Country within the region
  • Last two letters: Specific airport or facility
ICAOLocationBreakdown
EDDFFrankfurt/Main, GermanyE = Northern Europe, D = Germany, DF = Frankfurt
LOWWVienna, AustriaL = Southern Europe, O = Austria, WW = Vienna
KJFKNew York JFK, USAK = USA, JFK = Identifier
EGLLLondon Heathrow, UKE = Northern Europe, G = UK, LL = Heathrow
OMDBDubai Intl, UAEO = Middle East, M = UAE, DB = Dubai

Types of ICAO Codes

Code TypeUse
Airport codesEDDF, EGLL, KATL — used in flight plans, METARs, NOTAMs
FIR/UIR codesEDMM (Munich FIR), LIMM (Milan FIR)
Navaid codesE.g., LUX VOR = LUX (not always ICAO format)
ATC facility identifiersUsed in logon addresses for CPDLC or ground services

Where ICAO Codes Are Used

ApplicationExample
Flight plans (Item 13/16)DEP/ARR = LOWW/EDDF
ATIS and D-ATIS“EDDF ATIS Bravo, time 1020 Zulu”
METAR/TAF“METAR LOWW 101250Z…”
Radio callsigns“Langen Radar, this is D-EXYZ, inbound EDDS”
CPDLC logonsLogon to EDYY (Eurocontrol UAC)

Tips for Pilots and Dispatchers

  • ✅ Memorize the ICAO codes of your home base, alternates, and frequent destinations
  • ✅ Use ICAO codes when filing international flight plans
  • ✅ In cockpit systems, always enter the 4-letter ICAO code — not the IATA version
  • ✅ Practice identifying ICAO codes using LearnATC route-planning modules






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