Four Pillars Airport (ICAO: AZ21) is a small, privately owned general aviation airfield located in Huachuca City, Arizona, United States. It serves private pilots and light aircraft operations in the southeastern corner of the state, near the U.S.-Mexico border region. The airport is situated in Cochise County, an area known for its high desert terrain and proximity to Fort Huachuca, a major U.S. Army installation. Like many small general aviation fields in rural Arizona, it primarily supports private recreational and utility flying rather than commercial passenger service.