The expedition was led by Americans Dan Futrell and Isaac Stoner.
On New Year's Day in 1985, a Boeing 727 crashed into the side of a South American mountain with 29 people on board. Until now, it's remained one of the world's greatest aviation mysteries.
Eastern Airlines Flight 980 was on its way from Paraguay to the United States, via Bolivia and Ecuador. It had just been cleared to descend for landing at La Paz when it slammed into Mount Illimani, bursting the fuselage and scattering debris across the surrounding rocks and ice.
The crash site was inaccessible due to heavy snowfall. Rescuers were forced back by avalanches. Helicopters couldn't operate in such thin air. When a private group of Bolivian mountaineers successfully navigated the terrain two months later, they found debris and luggage.
No bodies. No black boxes.
All-in-all, five teams made it to the site, but each came back empty-handed. Eventually, investigators ruled out the possibility of a bird strike, engine malfunction, or hijackers.
Conspiracy theories swirled. What if it was inexperienced crew? Bad weather? The Paraguayan mafia? Maybe Eastern Airlines was running drugs? Was it a bomb?
NO-ONE HAD ANSWERS, UNTIL NOW
A new report in OutsideOnline.com, by journalist Peter Frick-Wright, has blown the case wide open. He accompanied two friends on their mission to find the lost plane: Dan Futrell, an affable former-soldier who served two tours of duty in Iraq; and Isaac Stoner, an analytical Harvard graduate who works in biotechnology.
Dan was in charge of learning about the crash and its history. Isaac was responsible for keeping them alive. They spent five months working on their fitness and training for altitude, before taking off for Bolivia with a crazy plan, a bit of savings, and two weeks of holidays.
They aimed for a 1.6km-square patch of glacier about a kilometre below the crash site, figuring plane parts have spent 30 years sliding down the mountain due to heavy snow and gravity.
Together with a German-born climbing guide called Robert Rauch, and a cook named Jose Lazo, they climbed into a Land Cruiser and headed for the mountains. They drove down a valley, forded a river, and bumped up the other side past a uranium mine. Three kilometres from their campsite, a rockfall blocked their path.
"Dan and Robert walk to the uranium mine and return 10 minutes later. 'Cinco porters-o,' Dan tells us, exhausting his knowledge of Spanish. 'They'll carry our shit-o. Up the mountain-o.' This is great news, except we packed like we were driving all the way to base camp, so even five porters won't be enough," wrote Frick-Wright.
The almost vertical hike didn't kill them, but Frick-Wright said it came close - especially since Lazo opted to go straight up the side, instead of winding their way up. Suffering due to a lack of oxygen, they stumbled over plane parts locals carried to the mine from the debris field.
"This is exactly what Dan and Isaac spent five months imagining a Bolivian mystery adventure would be like - scattered clues leading to a search area laid out in front of them like a Google map," he wrote.
FINDING THE FIRST BODY PART
Robert, the guide, stumbled across the first body part at about 1pm on the first day of searching.
"It's a femur, roughly 14 inches long and so dry that it's almost mummified. You can see skin, muscle, and fat still attached," Frick-Wright wrote.
They consider saying some words, but no-one can think of any.
"They dig a small grave, stacking rocks as a marker. Not long after, we find another bone - probably a tibia. Then, a few feet away, cervical vertebrae with frayed nerves still visible down the spinal column."
They sweated in the sun and shivered in the shade as they searched, scrambling between glacial fragments and rocks as chunks of ice break off and roar down the mountain.
They found pieces of fuselage and jet engines, wiring and switches, seatbelts and children's shoes, and an "astonishing number" of contraband crocodile and snakeskins that would have eventually been smuggled into the United States and turned into handbags. They found a roll of magnetic tape.
"It feels like our discoveries have only prompted more questions," wrote Frick-Wright. "What happened on all those other expeditions? Why didn't they find any body parts? And could you believe all those snakeskins?"
THE MYSTERY OF THE BLACK BOX
Contrary to their name, black boxes are actually orange. They contain a cockpit voice recorder and a flight data recorder, and they're capable of withstanding extreme temperatures, extreme pressure, and extreme impacts. Modern black boxes contain a locator beacon that pings for 30 days, but that wasn't necessarily the case in 1985.
The next day, the men searcher higher. They found wheels, pistons, hydraulics, life-jackets.
"By midmorning we're all thoroughly exhausted, and the novelty of new plane parts has worn off ... Here, in the newly melted ice, there's an almost comical number of parts."
They find a lump of green cloth tied with thick white yarn, filled with letters widow Judith Kelly left for her late husband William, one of the passengers, on her second expedition to the crash site. She lobbied fiercely for a more thorough investigation, and though America's National Transportation Safety Board funded another trip, it was a logistic disaster.
Although low on energy, the men became obsessed with finding the flight recorder.
They found a human neck, embedded with a piece of aluminium.
They searched. They dug. They chipped ice. Eventually, they gave up.
CONSPIRACIES BREED IN BETWEEN FACTS
That's when Isaac spotted the cockpit voice recorder. It was just metres from where they stopped for lunch - bright orange, and crushed almost beyond recognition. It turns out they'd been finding pieces of it the entire time.
Originally, they planned to hand in their finding to the US Embassy in La Paz, but they decided to take the pieces home to America in the hope of avoiding bureaucracy. However, when they reached out to America's Federal Aviation Administration, they discovered they'd accidentally violated the rules of international civil aviation, which states that the government of the country where a plane crashes is in charge of the investigation. Relations between the US and Bolivia are frosty, and no-one was willing to get involved until the legal issues were resolved.
"Conspiracies breed in the spaces between solid facts," wrote Frick-Wright. "Unless the NTSB decides to further strain diplomatic ties with Bolivia or gets permission to look at the tape and finds usable information - and both scenarios seem pretty unlikely - there will always be gaps in the story of Flight 980."
A PLAUSIBLE STORY
According to Frick-Wright, the most plausible story is that in addition to being an extremely difficult descent, the flight into Bolivia was troubled by a lack of radar, language problems between pilots and ground crew, a brewing storm, and little training.
La Paz has the highest airport in the world, and before landing, the captain was required only to watch a video about the landing. On his first trip, he was supposed to be supervised by a check pilot - someone who'd flown there before - but in this case, check captain Joseph Loseth was comfortably seated in first class when pilot Larry Campbell began the descent.
According to a report by America's Air Line Pilots Association, there were significant shortcomings with Omega, the on-board navigation system. Former investigator Don McClure said the system consistently steered flights between Paraguay and Bolivia eight kilometres off-course, in the direction of Mt Illimani.
"We can speculate that the storm, combined with lacklustre navigation equipment, inexperience, and bad luck, led Flight 980 straight into the side of Illimani, but it's still conjecture," reflected Frick-Wright. "Instead of case closed, it's case slightly less open."
Her van broke down 35km off-track in dense bushland near Karroun Hill.