Definition
K4F2 is the FAA Location Identifier for Outagamie County Regional Airport's former designation, now more commonly referenced as KATW (Appleton, Wisconsin). In the context of Figure 4-54 of the Instrument Procedures Handbook, K4F2 appears as a four-character identifier used on instrument approach charts and in flight planning systems to uniquely tag a specific airport. FAA Location Identifiers are alphanumeric codes (typically three or four characters) assigned by the FAA to airports, navigation aids, and fixes for use in flight plans, charts, ATC communications, and avionics databases.
Plain English
K4F2 is a short code that identifies a specific airport. The FAA assigns these codes so that pilots, controllers, and flight computers can refer to an airport quickly and without confusion, instead of spelling out its full name every time.
Context Anchor
Seen at the top of an instrument approach chart and in procedure examples, including the NDB approach figure in the FAA Instrument Procedures Handbook.
Derivation
The “K” comes from the international system of location indicators, where many airports in the contiguous United States begin with K. The “4F2” portion is the FAA’s assigned local identifier for that specific airport.
Why Pilots Care
Entering the wrong identifier sends you to the wrong airport in the avionics, loads the wrong approach, or files the wrong flight plan. Identifiers that mix letters and numbers (like K4F2) are easy to mistype, so pilots verify them carefully against the chart before using them.
Intuition Check
Do not read K4F2 as a frequency, fix name, or runway number. In this context, it is the airport’s identifier.
Example Sentence 1
The chart in Figure 4-54 shows the NDB approach for K4F2, so the pilot loaded that identifier into the GPS to bring up the procedure.
Example Sentence 2
After passing K4F2 the pilot began timing the final approach segment.