The National Air Traffic Controllers Association (NATCA) is a labor union and aviation safety organization in the United States that represents nearly 20,000 highly skilled air traffic controllers, engineers, and other aviation safety-related professionals. NATCA is one of the strongest labor unions in the United States federal sector and represents a range of aviation safety professionals in 15 FAA bargaining units, 4 Department of Defense air traffic facilities, and 102 federal contract towers. These air traffic controllers and other aviation safety professionals make vital contributions to the U.S. economy and make modern life possible by coordinating the safe, orderly, and expeditious movement of nearly one billion aviation passengers and millions of tons of freight within the National Airspace System each year. NATCA is headquartered in Washington, D.C., and is affiliated with the AFL-CIO.