Almost three years after a glacier 70 miles east of Fresno surrendered the first of two mummified airmen, their 66-year-old crash remains one of many enduring aviation mysteries in the sprawling Sierra Nevada.

Hundreds of military and private aircraft have fallen here, victims of some of the world’s most dangerous winds, sudden storms, no-way-out canyons or even their own mistakes.

Sometimes planes simply disappear. Adventurer-millionaire Steve Fossett, for example, may have crashed in the Sierra last year, but no trace of him or his plane has been found.

Sometimes the wrecks — or their victims — are discovered decades later. This is what happened in 2005 and 2007 with the discovery of two World War II-era bodies on Mendel Glacier — the first ice mummies ever found in the Lower 48 states.

For wreck chasers and amateur archaeologists, these mysteries are irresistible, a quest worthy of Indiana Jones. But the tallest mountain range in the Lower 48 states does not give up secrets easily.

Even with modern technology, the Sierra can frustrate searchers with its steep canyons and millions of acres of thick forest. The 400-mile-long mountain range covers more ground than the French, Swiss and Italian Alps combined.

“Very few people go into that country,” said G. Pat Macha, a well-known aviation archaeologist who has inspected more than 50 Sierra crash sites.

“It’s brutal. It’s dense, and in many places, sheer and vertical. Eventually, everything will turn up ... but it could be a long, long time.”

How many planes have crashed there?

Precise statistics are nearly impossible to gather because records are fragmented and incomplete. Macha, co-author of “Aircraft Wrecks in the Mountains and Deserts of California,” counts more than 650 Sierra crash sites — a figure that does not include accidents at airports or within towns.

These crashes are more than statistics or mysteries to be solved. They shatter lives, leaving deep emotional and sometimes physical scars. Relatives of the missing wait for news — sometimes for months, sometimes for decades, sometimes forever.

Survivors and relatives of the lost

Donnie Priest, now 37, lost his mother and stepfather in a 1982 plane crash on the border of Yosemite National Park. He also lost both of his feet. A Herculean effort by rescue crews plucked him from the snow-covered plane resting on an avalanche-prone slope.

Gene Ebell, a local insurance agent, and Robert Starr, a McLane High School student, endured 15 wintry days in the Sierra after crashing in 1970. They trapped water in air sickness bags and warmed their bodies with foam from seat cushions. Both were saved only because friends and family refused to stop looking.

Some searches end unsuccessfully. Families of those missing must move on with their lives, knowing they may never have closure.

William Ogle, a university professor in Florida, still hopes for word on his father. Businessman Charles Ogle vanished in 1964 on a solo plane flight from Oakland to Reno, Nev.

When pilots searching for Fossett spotted a few unfamiliar wrecks last year, William Ogle wondered whether one could be his father’s plane. All but one wreck have been ruled out. Ogle, who was 5 when his father disappeared, concedes he may never know the truth.

“I won’t hold my breath,” he said. “I’ve been holding my breath for a long time.”

But there is great joy when a mystery is solved — especially one dating back to World War II. The discovery of Ernest “Glenn” Munn, the mummified airman found last year, surprised his three sisters, who brought his remains home to Ohio for burial.

“We had been wondering all those years,” said one of Munn’s sisters, Sarah Zeyer. “It’s just wonderful to know he was found.”

World War II era

The Sierra claimed many of its victims during the early 1940s.

More than 2,000 airmen perished in California during those few years, said Tony Mireles, author of a book tracking stateside Army Air Force fatalities during World War II. He estimates another six to 10 nonfatal accidents occurred for each fatality.

In the early 1940s, the military accelerated aviation training and established dozens of big and small airfields in the Golden State.

Mireles said young, inexperienced pilots in training sometimes were cocky or careless — and their airplanes unforgiving. Tricky Sierra weather made training missions even more treacherous.

“Flying over that territory was pretty darn dangerous, and still is,” he said.

More than half the missing military aircraft in California likely rest within the rugged Sierra, said Don Jordan, who joined Macha to co-author “Aircraft Wrecks in the Mountains and Deserts of California.”

Jordan and Macha’s book is peppered with mentions of military planes that flew into the Sierra but never came back. That includes the ill-fated navigation training flight of 2nd Lt. William Gamber and cadets John Mortenson, Leo Mustonen and Munn, who vanished along with their twin-engine AT-7 Beechcraft on Nov. 18, 1942.

Was it pilot error? Or did a November storm take down this flight? Nobody knows, but Fresno meteorologist Steve Johnson is trying to solve the weather piece of this puzzle.

“I’m having dreams about this crash,” he said.

Tilted mini-tornadoes

The Sierra can be perilous even for well-trained aviators. There are treacherous winds, sudden storms and deceptive landscapes.

The mountain range is perfectly placed for violent weather. It is the first significant barrier for storms from the Pacific Ocean. The wind hits 70 miles per hour from run-of-the-mill winter weather fronts, crashing into the high-elevation granite and walloping the range with snow.

In spring and fall, huge blasts of wind, known as mountain waves, blow over the Sierra and cause tilted mini-tornadoes called rotors. These eastern Sierra winds can pull a plane apart.

“You need to pay attention to the weather forecasts,” says private pilot William Hill, who is part of the Federal Aviation Administration’s safety team in Redding. “You’re never going to outsmart or outdo Mother Nature.”

Big winds have factored into many crashes of private planes, experts say. Small planes generally fly lower than commercial jets, which are many thousands of feet above miles-high peaks and dangerous bursts of wind closer to the ground.

The Sierra also presents a survival challenge most months. At high elevations, temperatures drop into the teens and 20s for many months of the year. The deep snow makes it almost impossible to hike out after a crash.

Ice mummies

The frigid conditions and high elevations are why the mountain range has glaciers. Those conditions can preserve bodies of plane crash victims for decades.

In 2005, ice climbers found the first of two World War II airmen, Mustonen, on Mendel Glacier in northern Kings Canyon National Park. A year ago, Munn’s body turned up just 100 feet away.

Seattle author Peter Stekel, who is writing a book about the wreck, found Munn’s body last year. He hopes to make more discoveries in September, when he again visits Mendel Glacier.

Stekel has done a year of research and believes he has a better idea of where to look for pieces of the 1942 wreckage: “I feel pretty confident that I should be able to find more.”