The Aviation Unit of the United States Park Police began in April 1973 and was placed under the command of Lt. Richard T. Chittick. It started with one Bell 206B JetRanger and a staff of three pilots and three rescue technicians based at the Anacostia Naval Air Station in a shared space with the MPD Aviation Branch. A second helicopter, a Bell 206B-3 JetRanger, was added in 1975 and the unit relocated to Andrews AFB. The Aviation Unit moved to its present facility in Anacostia Park, the "Eagle's Nest," in 1976. In 1983, the 206B-3 was upgraded to a Bell206L-3 LongRanger. Their first twin-engine helicopter, a Bell 412SP, and the third helicopter to carry the designation "Eagle One," was placed in service in January 1991. The unit grew to its current staff, and began providing 24-hour coverage in January 1994.