Senior Airman Elizabeth Rissmill / Air Force photo Air Force MC-12W spy planes like this have played a key role in capturing or killing more than 700 high-value insurgents in Afghanistan, the Air Force says.

Sometimes, a 99.96% success rate isn’t good enough. That’s how often the Air Force’s MC-12W Liberty spy planes arrive overhead when needed by U.S. troops on the ground in Afghanistan.

The twin-turboprop planes are modified versions of the Hawker Beechcraft Super King Air 350. Their crew of four includes a pair of pilots and a pair of backseat sensor operators, who funnel video to ground-pounders down below. The fleet has played a key role in the killing or capture of more than 700 high-value insurgents in Afghanistan over the past four years, the Air Force says.

You might think that a mission aboard an unarmed propeller-driven plane, flying lazy orbits and trying to locate and video troublemakers far below, is a relatively simple task in skies filled with bomb-laden jet fighters and missile-firing helicopters.

But you would be wrong.

Even the most mundane-sounding mission can go haywire when the demands of war press a service to develop a needed capability quickly, and to deploy less than optimally-trained pilots to the fight.

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“The crew of the Mishap Aircraft, call sign Independence 08, were outstanding combat veterans, with impeccable reputations,” the Air Force says in a just-released investigation into an April 27 accident that killed the entire crew. “These four represented America’s best airmen and served numerous rotations in the Middle East putting their lives on the line for our nation.”

The plane took off from Kandahar air field at mid-day. After a 30-minute flight 110 miles northeast, the aircraft began tracing a leftward orbit in the sky, using various sensors to seek out a high-value insurgent that soldiers on the ground wanted to get.

It found him — and bad weather — about 10 minutes later. “Looking at scattered and broken 16-170, plus this giant thing we’re flying around going up to about FL240,” one of the back-seaters radioed at 12:34 p.m. Translation: there were scattered clouds beginning at about 16,500 feet above sea level, and a rapidly-rising towering cumulus cloud reaching to 24,000 feet right in front of them. The rugged terrain down below averaged about 6,000 feet above sea level.

The pilot, sitting in the left front seat of the $20 million plane, began climbing to get try to get out of the clouds. He ordered the climb through the plane’s autopilot, which isn’t completely “auto”: the pilot must manually adjust the plane’s power to maintain airspeed during the climb.

“While or just after initiating the climb, the Mishap Pilot continued working an orbit adjustment to better service tracking an active target,” the probe says. Amid the clouds — with no visual clues outside the cockpit as to speed or orientation — 25 seconds passed before the pilot realized that his plane, like The Little Engine That Could, was slowing down as it climbed.

“The crew’s vision was restricted by clouds near the time of departure from controlled flight and they likely did not have a visually discernible horizon,” the investigation says. “The lack of a visible horizon made it more difficult for the Mishap Pilot to recognize the Mishap Aircraft’s attitude and the loss of airspeed.”

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But eventually the pilot realized what was happening. “A little slow,” he acknowledged. “Correcting.” Too slow, he knew, and the plane could lose the lift that keeps it aloft and begin dropping like a stone.

But even as Independence 08 continued its climb, it had already started down a slippery slope. “From approximately 10 seconds from climb initiation until loss of [communications] feed, the climb rate increases and the airspeed decreases at a rapid rate,” the investigation says. “The Mishap Aircraft airspeed decreased from 150 knots to 116 knots during the final seconds of controlled flight.”

Seven seconds passed before the mission commander, sitting in the right front seat, spoke up. “Alright,” he ordered the pilot, according to a snippet of chatter captured by the cockpit voice recorder detailed in the report, without emotion or punctuation. “Firewall.” That was an order to push the plane’s throttles forward — “through the firewall” — and send more power to the propellers. “Max power, max power.”

This is where Independence 08 entered a perfect aerodynamic storm:

— To avoid the clouds, it was climbing. — It was already making a left-hand turn, as part of its prescribed orbit. — To fly the orbit, it was already banked to the left. — The MC-12W’s props do not spin opposite one another, but in the same direction. Boosting their power tugs the aircraft to the left.

Two seconds after the mission commander called for “max power,” the plane banked at least 50 degrees to the left, setting off an alarm.

Air Force photo / Staff Sgt. Manuel J. Martinez Inside the cockpit of an MC-12W in Afghanistan.

Four seconds later, the plane’s stall-warning horn sounded, signaling an imminent loss of lift. “Background noise,” the investigation notes, “indicates items flying around within the aircraft.”

At this point, the pilot’s display screen went blank, except for a series of red arrows, pointed upward. “Whoa,” the pilot said. “Pull up.” The airplane most likely had entered a dangerous spin on the verge of becoming a deadly spiral. But pulling up — as directed by the red arrows on the cockpit screen — would only make recovering from either more difficult.

“My aircraft,” the more experienced and senior mission commander said nine seconds later, asserting his right to take control of the plane as it plummeted toward the ground at 134 miles an hour.

“Your aircraft,” the pilot agreed three seconds later, just before the cockpit voice recorder stopped recording. A second indicator showed the plane was now falling at 282 miles an hour.

Five seconds later, the aircraft was diving at 326 miles an hour. “Such rapid acceleration is indicative of an extreme nose-down attitude,” the Air Force investigation says. Twenty seconds later, it had reached an estimated 364 miles an hour. “The Mishap Aircraft lost approximately 15,000 ft before impacting the ground.” The span from initial climb to ultimate crash: 84 seconds.

No one aboard ever gave any thought to bailing out. “There is no crew egress option for an airborne MC-12W,” the probe notes. “There is no evidence the crew attempted to abandon the aircraft.”

But the crew, with a total of 8,824 flying hours, 4,846 combat flying hours, and 836 combat sorties, wasn’t the only party responsible for the accident.

There is an accompanying list of military corner-cutting that often takes place during war.

For starters, 60% of MC-12W pilots are assigned to the craft on a temporary basis. The mission commander had spent his career flying KC-135 Stratotanker refueling planes; the pilot had spent most of his flight time flying the EC-130H Compass Call electronic-warfare plane:

Both pilots were on their first MC-12W deployment and were inexperienced in their roles on the mishap sortie. Their limited recent experience was compounded by the fact that they had not flown together in the past…Inexperience would have made the Mishap Pilot less familiar with the MC-12W, affecting his visual scan and instrument crosscheck proficiency, and making him more susceptible to task saturation while tracking his first target on his first mission. This delayed detection of the pitch, the decreasing airspeed, and the imminent stall. During spin and spiral recovery, inexperience likely caused him to pull vice relax the yoke, and delayed prompt reduction of power. Finally, it was also the Mishap Mission Commander’s first flight as a newly qualified certifier who was just completing his second month of his first MC-12W deployment. This explains his delayed intervention in both preventing the stall and recovering the Mishap Aircraft. Limited weapon system experience is common with MC-12W combat operations due to the high rate of crews temporarily assigned to the platform. This is a result of known program risks.

They initially train in simulators based on the civilian version of the plane, before shifting into MC-12Ws at Beale Air Force Base, Calif., for final training. The simulators are markedly different from the plane they will fly in combat and “both training and aircraft experience affect basic airmanship skills including recognition of and recovery from unsafe aircraft attitudes”:

The MC-12W is physically different, its mission is different, and it is more mentally demanding and challenging than the King Air 350. For example, the MC-12W has over 40,000 additional parts and systems, and different aerodynamic characteristics. It is fitted with extra fuel tanks and an array of antennae and other external equipment, weighs more, and has more drag than the King Air 350. The MC-12W did not undergo normal developmental or operational testing to account for these differences.

There is insufficient training on how to recover from a stall:

This is significant as a typical mission sortie includes substantially more time in orbit than in any other phase of flight, and the orbit is flown relatively close to stall speed. Four previous MC-12W orbit stalls that resulted in significant, near catastrophic altitude loss highlight this limited training. These four near misses occurred in adverse weather and also show why training and experience in weather is important. Training in the often unpredictable weather experienced in Afghanistan cannot be replicated at Beale Air Force Base, where it is largely clear all summer and has mild winter weather…[A lack of training about the proper response to the “pull up” arrows in an emergency also could have] lead to confusion and delayed or improper stall/spin recovery…In either a spin or spiral, these modes can cue the pilot to “pull up,” by pointing towards the horizon, which is the opposite required for proper recovery. In this mishap, the evidence indicates the Mishap Pilot received such a cue and likely pulled on the yoke during the spin.

But all of these shortcomings, the accident probe says, are risks that must be weighed in war:

The MC-12W program was started in 2008 to field immediate Intelligence, Surveillance and Reconnaissance capability for combat operations in Iraq and Afghanistan and went from contract to first combat sortie in 8 months. This urgency led to several aspects of the program not being normalized, which created increased risk, particularly aircrew inexperience and lack of instructors in the combat zone. Most mission commanders are deployed with approximately 20 hours of MC-12W primary flight time. Additionally, numerous aircrews, known as “flow-throughs,” are loaned to the program from other weapon systems for 9 months and then returned to their primary airframe, creating continuous inexperience in the program…With 20 percent of the aircrews rotating in and out of Afghanistan each month, it is not uncommon for pilots to fly together for the first time on a combat sortie, such as happened in this mishap. Unfamiliarity hampers crew coordination, and the Mishap Mission Commander was slow to intervene in this mishap. The result of this program risk is inexperienced MC-12W pilots deployed in combat, and inexperience substantially contributed to this mishap.

Nearly all of Independence 08 ended up smashed inside a 50-meter circle amid rugged Afghan terrain. The right wingtip — subject to the most severe stress during a lefthand spiral — separated from the plane before impact and ended up 500 meters from the crash site.

It took about two hours for U.S. troops to reach, and secure, the wreckage.

Soldiers love the airmen above who help them fight and win. So their report two hours after their arrival came as no surprise to anyone who has witnessed what air superiority can do for grunts on the ground: “4 HEROES RECOVERED.”