With the promulgation of Federal Aviation Regulations for small unmanned aircraft systems, the volume of unmanned flight operations is expected to increase, which demands an analysis of potential hazards to the National Airspace System. Descriptive statistics were used to investigate reports archived in the Aviation Safety Information and Analysis and Sharing system involving unmanned aircraft systems, as well as the FAA UAS Sightings Reports database. The frequency of reports involving airspace violations, and Near Mid-air Collisions by unmanned aircraft systems as well as an analysis of the location, sponsor category, phase of flight, altitude, and airspace type in which the incident occurred were investigated. An upward trend was observed in the number of events with 2015 showing the highest frequency. Most events took place in California and New York and often transpired in Class B Airspaces. The cruise and approach to landing portions of the flight envelope account for the highest number of UAS-related events. A majority of reported events took place between 1000 feet and 2000 feet above the ground and were academic institution sponsored activity. Additionally, the majority of events involved conflicts with commercial manned aircraft transporting passengers.