Helicopter aerodynamics, common flight techniques, normal field operations, and precautionary measures and critical conditions are discussed. This is U.S. Army handbook FM 1-51.About the Author: The Federal Aviation Administration (FAA) is the government agency that regulates and sets standards for the aviation industry. The National Aeronautical Charting Office (NACO) is a division of the FAA dedicated to aeronautical chart research, drafting, maintenance and publication.