The Disappearance of Flight 2501: Why the search is ending for the plane lost over Lake Michigan

SOUTH HAVEN, Mich. — In a shaded section of an old cemetery in South Haven, Michigan, a boulder with a black inscription signifies a mass grave where a number of body parts from those aboard Northwest Orient Airlines Flight 2501 are buried.

The ill-fated flight, at the time the deadliest commercial airline disaster in American history, disappeared when it flew into a storm over Lake Michigan in the early morning hours of June 24, 1950.

None of the souls on the plane — 55 passengers and three crew members — survived. To this day, the plane's final resting place has not been found, and no complete bodies have ever been recovered from the crash.

"There was nobody famous on this, but each person was so significant to their families," said Valerie van Heest, executive director of the Holland-based Michigan Shipwreck Research Association.

"Their loss was so incomprehensible, especially if you don't have a body, especially if you don't have a reason," she said.

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For the past 20 years, van Heest has searched for the wreckage from NWA Flight 2501, scouring nearly 700 square miles of Lake Michigan with sonar technology, moving back and forth over the freshwater expanse as if she were mowing the lawn.

Now, van Heest says she will search no more.

"We have found it's impossible to find," she said. "Maybe someday, some weather incident will churn up the lake bottom and reveal the debris from the plane, but if not, we've done the best we could."

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The crash and the search

On the evening of June 23, 1950, Northwest Orient Airlines Flight 2501 departed from New York's LaGuardia Airport en route to Seattle, planning to stop in Minneapolis and Spokane along the way.

As a squall line over Lake Michigan approached the westbound plane, its pilot requested a drop in altitude, but was denied the clearance due to nearby air traffic.

Then, several miles off the shore of Benton Harbor, it flew into the storm and was never heard from again.

"Today, you would never fly under a squall line. That would be lunacy," van Heest said.

"They didn't understand that back then," she said. "The pilot did his best to continue on with that flight, but his decision to continue across the lake is what made this a fatal crossing of Lake Michigan."

WATCH: The Disappearance of Flight 2501

When the DC-4, converted from a WWII-era C-54 into a commercial aircraft, did not respond to radio requests and failed to pass by an airfield in Milwaukee at its scheduled time, a search began for the missing plane.

The U.S Coast Guard patrolled Lake Michigan while bits and pieces of the plane, as well as body parts, began to wash up on West Michigan's shoreline, including in South Haven, where the mayor closed the city's beaches just before the Fourth of July.

"A gruesome accident," van Heest said. "The largest person found was a torso. No arms. No lower half. No head."

In a week's time, according to the historian, authorities deemed finding the wreckage to be an impossible task.

"They gave up," she said.

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A half-century later, van Heest and Clive Cussler, a world-renowned shipwreck hunter, picked up where the federal government left off, using side-scan sonar to look for the long-lost plane.

They discovered nine shipwrecks in the search area, but no evidence to pinpoint exactly where or exactly why the plane crashed.

It's likely, van Heest says, the aircraft either blew up when it was struck by lightning or broke into a "thousand pieces" upon impact with the water, the largest of these parts settling into the deep muck of the lake bed over decades.

Valerie van Heest

The two found other things, though, including perhaps a semblance of closure for the families whose loved ones were lost on the fatal flight.

"We really brought this accident back to the public's attention," van Heest said. "People know about this accident. People are curious about it, and our work has made sure this accident would not be forgotten."

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During van Heest's search and research, which included writing a book on Flight 2501's disappearance, she discovered the mass grave in South Haven's Lake View Cemetery and another in St. Joseph. At the time, both were unmarked. She's since hosted memorial services and put on display a number of personal artifacts of the victims, including one man's tattered suit coat and his checkbook, complete with an entry for his ticket for the flight: $49.30.

Strangely, these artifacts and the lack of a large-scale discovery are perhaps more significant for the memory of the 58 passengers and crew.

"They've been remembered," van Heest said.

"We really provided the answers to what happened to this plane," she said. "We simply don't know the exact spot on Lake Michigan where it happened."

This article was written by Sam Landstra for the Scripps News Group in Grand Rapids.