The Federal Aviation Administration should improve its risk management efforts related to drone safety, according to a report by the U.S. Government Accountability Office.

FAA’s information on the extent of unsafe use of small unmanned aircraft systems, more commonly known as drones, in the national airspace system is limited, according to the GAO report published Thursday. Although the agency collects data on several types of safety events involving small UAS, the accuracy and completeness of the data are questionable, the report found.

Since 2014, for example, more than 6,000 sightings unmanned aircraft systems — often flying near manned aircraft or airports — have been reported to the FAA, but agency officials told the GAO that they cannot verify that the drones were involved in most of the sightings.

“Officials explained that small UAS are often difficult for pilots to identify definitively and typically are not picked up by radar,” the GAO said in its report. “Such data limitations impede the agency's ability to effectively assess the safety of small UAS operations.”

The FAA is taking steps to improve its data, including developing a web-based system for the public to report any drone sightings perceived to be a safety concern and surveying UAS users on their operational activity, but the agency did not have time frames for completing these efforts, according to the report. The FAA is also evaluating technologies for detecting and remotely identifying UAS, which could improve data on unsafe use.

Of the five key principles of safety risk management in its policies, FAA followed principles of defining appropriate roles and responsibilities for safety risk management and describing the aviation system under consideration, according to the report.

The agency also partially followed the other three principles: analyzing and assessing safety risks; implementing controls to mitigate the risks; and monitoring the effectiveness of the controls and adjusting them as needed. For example, the FAA did not consistently analyze and assess safety risks in terms of their severity and likelihood because it did not have sufficient data to do so.

“Improved risk management practices would help FAA determine whether additional actions are needed to ensure the safety of the national airspace and provide FAA and other decisionmakers with confidence that FAA is focusing on the most critical safety risks posed by small UAS,” the report said.