K ? United States The prefix K is generally reserved for the contiguous United States. The ICAO codes for these airports are usually the FAA location identifier prefixed with a K.

In the world of aviation, the letter "K" at the start of a 4-letter ICAO airport code signifies that the airport is located within the contiguous United States. For example, the ICAO code for Los Angeles International is KLAX, and for New York JFK, it is KJFK. The International Civil Aviation Organization (ICAO) uses a regional system for the first two letters of its codes; "K" is the unique prefix assigned to the "lower 48" states. It is important to note that this rule does not apply to Hawaii or Alaska; Hawaiian airport codes start with PH (Pacific, Hawaii), and Alaskan codes start with PA (Pacific, Alaska). Most travelers are more familiar with the 3-letter IATA codes (like LAX or JFK) used for baggage tags and booking, but for pilots and air traffic controllers in 2026, the "K" prefix is the definitive identifier that a flight is operating within the primary American domestic airspace.

Excellent question! The “K” in U.S. airport codes is a systematic prefix that identifies airports within the contiguous United States (the lower 48 states).

Here’s a detailed breakdown of what it means and how it works:

The Core Rule

• K + ICAO Code: The “K” is the ICAO (International Civil Aviation Organization) country code for the contiguous United States.
• Example: Los Angeles International Airport has the IATA code LAX (used for ticketing, baggage tags, and passenger-facing info). Its ICAO code is KLAX (used by pilots, air traffic control, and flight planning systems).

The System and Exceptions

The “K” prefix is part of a broader ICAO system for North America:

1. Contiguous United States (Lower 48): K (e.g., KJFK for New York, KORD for Chicago, KDEN for Denver).
2. Alaska: PA (e.g., PANC for Anchorage).
3. Hawaii: PH (e.g., PHNL for Honolulu).
4. U.S. Territories:
   • Guam & Northern Mariana Islands: PG (e.g., PGUM for Guam).
   • Puerto Rico & U.S. Virgin Islands: T (e.g., TJSJ for San Juan, Puerto Rico).

Why the Confusion?

The mix-up happens because in the U.S., the public almost exclusively uses the three-letter IATA code (LAX, JFK, ORD). You rarely see the “K” unless you’re looking at a pilot’s flight plan, listening to air traffic control, or browsing an aviation map.

However, many major