https://www.gao.gov/assets/700/692010.pdfInteresting report. From my perspective the FAA has leaned perceptibly toward the UAS advocates who basically deny or minimize risks to crewed aircraft. "There is no record of serious injury or accidents from a UAS and crewed aircraft collision" and "most drone sightings and NMAC reported by pilots are unverified" seems to be the mantra among some apologists for drone operator misbehaviors. GAO appears to agree... while putting it much less bluntly.