While commercial drone flights will be allowed next year, an investigation by The Washington Post found that there have been more than 400 crashes by large U.S. military drones since 2001.

The accidents are a “record of calamity that exposes the potential dangers of throwing open American skies to drone traffic," the story says.

The article reports: “Since the outbreak of the wars in Afghanistan and Iraq, military drones have malfunctioned in myriad ways, plummeting from the sky because of mechanical breakdowns, human error, bad weather and other reasons, according to more than 50,000 pages of accident investigation reports and other records obtained by The Post under the Freedom of Information Act.”

No one has died from a drone accident, but the records show that there have been near misses, the report adds.

The accidents were caused by “fundamental safety hurdles,” the piece notes. They include a drone and its operator’s limited ability to notice and detect problems; pilot error; mechanical defects; and unreliable communication links between drones and their operators.

As previously reported, the Federal Aviation Administration has agreed to consider a request from Hollywood production companies to give them the nod to use drones for filming.