Marine Air Control Squadron 1 (MACS-1) is a United States Marine Corps aviation command and control squadron . The squadron provides aerial surveillance, air traffic control, ground-controlled intercept, and aviation data-link connectivity for the I Marine Expeditionary Force. It was the first air warning squadron commissioned as part of the Marine Corps' new air warning program and is the second oldest aviation command and control unit in the Marine Corps. The squadron is based at Marine Corps Air Station Yuma and falls under Marine Air Control Group 38 and the 3rd Marine Aircraft Wing.