In most instances, military officials convened an accident investigation board to determine the cause. In 18 cases, the drone crashes were so sensitive that the military classified the names of the countries where they occurred and details of what happened.
Two hundred and twenty-four drones crashed in Class B accidents that, under current standards, cost between $500,000 and $2 million. Officials withheld basic details about those mishaps, such as the dates and locations, on the grounds that the lesser damage totals did not warrant a public investigation.
The military documents do not include information about drones operated covertly by the CIA. The spy agency has its own fleet of about 30 armed Predator and Reaper drones overseas, all flown remotely by Air Force pilots assigned to the CIA.
The CIA also flies highly advanced RQ-170 Sentinel surveillance drones, including one that U.S. officials have acknowledged went down in Iran in December 2011.
Air Force leaders circulated briefing materials that quoted an unnamed general as saying, “What I worry about is the day I have a C-130 with a cargo-load of soldiers, and a [drone] comes right through the cockpit window.”
The general’s worries were well founded. On Aug. 15, 2011, a C-130 Hercules weighing about 145,000 pounds was descending toward Forward Operating Base Sharana, in eastern Afghanistan. Suddenly, a quarter-mile above the ground, the huge Air Force plane collided with a 375-pound flying object.
“Holy shit!” yelled the Hercules’s navigator, according to a transcript of the cockpit voice recorder. “We got hit by a UAV! Hit by a UAV!”
It was an unmanned aerial vehicle, or UAV in military jargon. An RQ-7B Shadow, flown by an Army ground crew, had smashed into the cargo plane’s left wing between two propellers. Jet fuel cascaded out of a gash in the wing.
The Hercules crew shut down one engine and radioed to clear the runway. Within two minutes, the plane landed, smoke pouring from the left side. “There’s a big frickin’ hole in the airplane,” the pilot said, according to the cockpit voice recorder. No one was hurt.
About 50 seconds later, the unwitting drone operator radioed the control tower to confess he had lost track of his aircraft.
“We had a, ah, C-130, um, that hit a UAV,” the air-traffic controller responded. “I’m suspecting that it’s yours.”
The military has never publicly disclosed the outcome of the investigation. Two Pentagon officials said in interviews that the drone operator was not at fault, but they did not give further details.
In response to a FOIA request from The Post, the Air Force released hundreds of pages of documents from its safety probe. The official finding of what caused the crash was censored, but some of the documents suggest the air-traffic controller was at least partly blamed. The records show the controller, a civilian contractor whose name was redacted, was temporarily demoted and given remedial training.
Military officials said there has been only one other case of a midair drone collision, involving a helicopter and a small, hand-launched drone in Iraq a decade ago.
Close calls on the ground have been more frequent.
A row of empty shipping containers, it turned out. Nobody was hurt. Scardaci did not respond to a request for comment through an Air Force spokeswoman.
In eastern Afghanistan, Predators armed with Hellfires crashed near residential areas in the city of Jalalabad twice in the space of six months.
In one instance, on Aug. 20, 2011, a drone “began falling out of the sky” after its propeller broke. “I looked below us, and there were houses everywhere,” the camera operator told investigators.
The Predator smashed into two Afghan housing compounds and sparked a fire. No one was hurt. The military compensated the homeowners with an undisclosed amount of money.
‘Oops’ and ‘uh-oh’Inside ground-control stations, drone pilots sit with binders of checklists that guide them through every conceivable scenario. But costly errors are still easy to make.
One recurring mistake: forgetting to turn on the Stability Augmentation System, which prevents the drone from going wobbly or into a spin. In at least five cases, pilots did not switch it on, or accidentally switched it off, then sat perplexed as the aircraft went into a nose dive.
On Aug. 16, 2010, neither the pilot nor the camera operator noticed the bright red warning lights on the video screens in front of them when their Predator took off from Balad air base in Iraq with the stabilizer turned off.
“That’s freaking us!” the camera operator yelled as the drone crashed, leaving a hole three feet deep near the runway. “What in the hell happened?” Investigators blamed “pilot inattention” for the accident.
In four cases between 2009 and 2012, Air Force officials determined that pilots were willfully negligent, placing them under investigation for suspected dereliction of duty, a criminal charge under military law.
One flew a Predator, unintentionally, into a 17,000-foot Afghan mountain, even after he was warned to watch out for high terrain.
Investigators concluded that the inexperienced pilot was rushing to help troops on the ground and preoccupied with nearby storm clouds, unaware of the mountain looming ahead.
The accident reports do not disclose the outcomes of the dereliction-of-duty cases or identify the pilots. Air Force officials declined to elaborate.
In another dereliction case, voice-recorder transcripts show an irritated camera operator lecturing a habitually nervous pilot right before takeoff at Jalalabad on July 24, 2012.
Sure enough, a few minutes later — oops. The armed Predator rammed a runway barrier and guardhouse.
“Whoa,” the pilot said. “I don’t know what the hell just happened.”
Reliability gripesThe original Predator was designed without redundant systems common to larger, manned aircraft. It bore only one engine, one alternator, one propeller. If any of those parts failed, the plane would come down.
Since the drone program began, the Air Force has acquired 269 Predators. Forty percent have crashed in Class A accidents, the most severe category. An additional 8 percent wrecked in Class B accidents.
As the accidents piled up, Air Force crews griped about reliability. Some of the complaints were aimed at General Atomics, the manufacturer.
“I don’t want to be the one that crashes a plane, but I hope that this causes folks, and when I say folks, I mean GA [General Atomics], I hope we hold them accountable for some of this stuff,” Air Force Maj. Elizio Bodden, a Predator instructor pilot, told an accident investigation board after a crash in Iraq on Nov. 29, 2007. “We know we are flying with some defective stuff, but we still do it.”
Pace, the General Atomics executive, blamed most Predator accidents on pilot mistakes during landings. He said that the company has made some safety upgrades to the aircraft but that adding extra engines or duplicate power systems was not practical, because it would require “a big redo.”
He noted that the aircraft has a limited future. General Atomics ceased production of the original Predator model in 2011 and replaced it with the MQ-9 Reaper, a more reliable aircraft that can fly twice as fast and carry more missiles and bombs. The Air Force plans to stop flying Predators by 2018 and has not been “interested in putting their money into upgrades,” Pace said.
During its first dozen years of existence, the Predator crashed at an extraordinarily high rate — for every 100,000 hours flown, it was involved in 13.7 Class A accidents.
Since 2009, as the Air Force has become more experienced at flying drones, the mishap rate for Predators has fallen to 4.79 Class A accidents for every 100,000 flight hours.
Army crash ratesThe Reaper has fared better than the Predator, incurring 3.17 Class A mishaps per 100,000 hours over the past five years.
Air Force officials pointed out that the crash rate for Reapers now approaches the standard set by two fighter jets, the F-16 and F-15, which over the past five years have posted Class A mishap rates of 1.96 and 1.47 respectively, according to statistics from the Air Force Safety Center at Kirtland Air Force Base in New Mexico.
“We’ve learned a lot about flying [drones] because we had to,” said Air Force Col. James Marshall, the safety director for the Air Combat Command. “War is a great motivator when lives are on the line.”
The Reaper has not been immune to deficiencies.
After one crashed during a training mission in California on March 20, 2009, Air Force investigators blamed a faulty temperature control valve in the oil system. A similar incident had occurred one month before.
Further investigation revealed that sliders in the valves had been installed upside-down. Air Force inspectors were even more surprised to learn from General Atomics that the firm had bought the valves from a Houston company that did not design its products for use in airplanes.
The valve “is not of aerospace grade. In other words, the thermostatic valve was designed specifically for industrial applications ONLY,” an Air Force investigator wrote in the accident report. “This thermostatic valve was not intended for aircraft.”