Ryan Airfield, also known as Ryan Field, is a city owned, public use airport located 10 nautical miles (12 mi, 19 km) southwest of the central business district of Tucson, a city in Pima County, Arizona, United States. It is included in the National Plan of Integrated Airport Systems for 2011–2015, which categorized it as a reliever airport. It is mostly used for general aviation but also serves a significant amount of law enforcement and military helicopter activity. Approximately 50% of Ryan's traffic is training-related.Although most U.S. airports use the same three-letter location identifier for the FAA and IATA, this airport is assigned RYN by the FAA but has no designation from the IATA (which assigned RYN to Royan - Médis Airport in Royan, France). The airport's ICAO identifier is KRYN.