Which code system uses a four-letter format for flight operations?

Which code system uses a four-letter format for flight operations?

• A. ICAO
• B. IATA
• C. UN/LOCODE
• D. FAA

Answer: (A)

ICAO uses a four-letter code system for flight operations. These four-letter identifiers are the international standard used in air traffic control, flight planning, and other official operational communications. They provide a globally consistent reference for airports, so pilots and controllers can coordinate across borders. Examples like KLAX for Los Angeles International or EGLL for London Heathrow illustrate how the codes are structured and used in real-world operations.

In contrast, IATA codes are three letters and are designed for passenger purposes—tickets, timetables, and baggage handling (LAX, LHR). UN/LOCODE codes are used for trade and logistics and are five characters long, not four (country plus location). The FAA is a U.S. authority that uses its own facility identifiers, primarily within the United States, and does not provide the universal four-letter code standard used globally for flight operations.