Definition
LOC is a multi-use aviation abbreviation. It can stand for (1) local or locally — referring to something occurring at a specific place, such as local weather conditions or a local altimeter setting; (2) location — the geographic position of a feature, facility, or aircraft; or (3) localizer — the lateral guidance component of an Instrument Landing System (ILS) that provides the pilot with left/right course alignment to the runway centerline during an instrument approach.
Plain English
LOC is a short form used in aviation writing that can mean local, locally, location, or localizer. Which one applies depends on the sentence around it. In approach charts and instrument flying, LOC almost always means localizer — the radio signal that keeps you lined up with the runway during an ILS approach.
Context Anchor
Seen in NOTAMs, charts, approach information, and short equipment or location notes where space is limited.
Derivation
All four meanings trace back to the Latin locus, meaning place. Local and location describe a place directly. Localizer was coined for the radio aid that locates the aircraft laterally relative to the runway centerline — it tells you where you are side-to-side.
Why Pilots Care
Because LOC has multiple meanings, pilots must read it in context. Mistaking a chart's LOC (localizer) reference for something general about location could lead to misreading an approach procedure. On an ILS, the localizer is the primary lateral guidance — losing it means losing your alignment with the runway.
Intuition Check
Do not assume LOC always means localizer. In FAA abbreviations, LOC can also mean local, locally, or location; the sentence around it tells you which meaning applies.
Example Sentence 1
The NOTAM advised that the runway lights were unserviceable LOC sunset to sunrise.
Example Sentence 2
NOTAMs often use LOC to indicate local restrictions around the airport.