According to a year-long investigation by The Washington Post, hundreds of military drones have crashed in major accidents around the world since 2001 and civilian drones are posing a new threat to passenger air traffic in the United States. Drones have revolutionized warfare and are set to revolutionize civil aviation under a 2012 federal law that will allow them to fly freely in American skies. But The Post found that the U.S. military and the Federal Aviation Administration suppressed widespread patterns of safety problems with drones and tried to keep details of accidents and near mid-air collisions a secret. Drawing on more than 50,000 pages of accident investigation reports and other records obtained under FOIA, The Post uncovered more than 400 major military drone crashes worldwide, including 49 in the United States. Some drone models were particularly crash-prone: almost half of the Air Force's iconic Predator fleet has been destroyed in accidents. The Post published details of 194 of the most serious accidents in an interactive online database, as well as crash-scene photographs, voice-recording transcripts and a video of a stricken Predator drone filming its own fiery breakup over Iraq. The Post also exposed a rash of dangerous encounters between civilian airplanes and drones flown in contravention of FAA rules intended to safeguard U.S. airspace, a problem that has worsened since the series was first published.