Unmanned Aircraft Systems: FAA Could Strengthen Its Implementation of a Drone Traffic Management System by Improving Communication and Measuring Performance, Report to Congressional Committees [open pdf - 2MB]
From the Highlights: "UAS [unmanned aircraft systems] have potential to provide significant social and economic benefits in the U.S. FAA [Federal Aviation Administration] is tasked with safely integrating UAS into the national airspace. UTM [UAS traffic management ecosystem], as planned, will be a traffic management system where UAS operators and service providers are responsible for the coordination and management of operations at low altitudes (below 400 feet), with rules established by FAA. The FAA Reauthorization Act of 2018 included a provision for GAO [Government Accountability Office] to review infrastructure requirements for monitoring UAS at low altitude. This report examines, among other things, the actions FAA has taken to develop UTM and additional steps needed to achieve UTM's implementation."
Government Accountability Office: https://www.gao.gov/