An interesting article...
"More than 400 large U.S. military drones have crashed in major accidents around the world since 2001, a record of calamity that exposes the potential dangers of throwing open American skies to drone traffic, according to a year-long Washington Post investigation...
...documents obtained by The Post detail scores of previously unreported crashes involving remotely controlled aircraft, challenging the federal government’s assurances that drones will be able to fly safely over populated areas and in the same airspace as passenger planes.
Military drones have slammed into homes, farms, runways, highways, waterways and, in one case, an Air Force C-130 Hercules transport plane in midair..."