Air Force Maj. Richard Wageman operates a Predator from a ground-control station in Afghanistan on Oct. 25, 2008. A week later, he was the pilot of a Predator that crashed into a U.S. military base. The precise cause of the crash was undetermined. (U.S. Air Force photo)

Investigators were unable to pinpoint a definitive cause for the accident but said wind and an aggressive turn by the pilot were factors. Wageman did not respond to a request for comment through an Air Force spokeswoman.

Several military drones have simply disappeared while at cruising altitudes, never to be seen again. In September 2009, an armed Reaper drone, with a 66-foot wingspan, flew on the loose across Afghanistan after its handlers lost control of the aircraft. U.S. fighter jets shot it down as it neared Tajikistan.

The documents describe a multitude of costly mistakes by remote-control pilots. A $3.8 million Predator carrying a Hellfire missile cratered near Kandahar in January 2010 because the pilot did not realize she had been flying the aircraft upside-down. Later that year, another armed Predator crashed nearby after the pilot did not notice he had squeezed the wrong red button on his joystick, putting the plane into a spin.

While most of the malfunctioning aircraft have perished in combat zones, dozens have been destroyed in the United States during test and training flights that have gone awry.

In April, a 375-pound Army drone crashed next to an elementary-school playground in Pennsylvania, just a few minutes after students went home for the day. In Upstate New York, the Air Force still cannot find a Reaper that has been missing since November, when it plunged into Lake Ontario. In June 2012, a Navy RQ-4 surveillance drone with a wingspan as wide as a Boeing 757’s nose-dived into Maryland’s Eastern Shore, igniting a wildfire.

Defense Department officials said they are confident in the reliability of their drones. Most of the crashes occurred in war, they emphasized, under harsh conditions unlikely to be replicated in the United States.

Military statistics show the vast majority of flights go smoothly and that mishap rates have steadily declined over the past decade. Officials acknowledge, however, that drones will never be as safe as commercial jetliners.

“Flying is inherently a dangerous activity. You don’t have to look very far, unfortunately, to see examples of that,” said Dyke Weatherington, director of unmanned warfare for the Pentagon. “I can look you square in the eye and say, absolutely, the [Defense Department] has got an exceptional safety record on this and we’re getting better every day.”

The Post’s analysis of accident records, however, shows that the military and drone manufacturers have yet to overcome some fundamental safety hurdles: