Huco is a series of flight regulations issued by the Federal Aviation Administration that apply to all aspects of flight operations in the United States. Huco stands for "Harmonized United States Commercial Operations Regulations." It covers all flight operations, from operating a commercial aircraft to operating a hobby aircraft such as a drone. Huco includes requirements for operating in controlled airspace, flight crew qualifications, aircraft certification and airworthiness, and medical qualifications. It also contains guidance on air traffic control, airspace designation, navigation, and aircraft design and construction. Additionally, Huco covers the safety aspects of flight operations, such as the selection and use of safety devices, emergency procedures, and the maintenance of aircraft. It also includes rules on hazardous materials transportation, noise abatement, and disaster preparedness.