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In the spring of 1952, a commercial plane flying from Puerto Rico to New York crashed into the Atlantic Ocean after losing power, killing 52 passengers and crew members. For the last 74 years, the location of the wreckage has remained a mystery—until now.
Researchers say they have located the remains of the Pan American Clipper Endeavor about five miles off the northern coast of Puerto Rico. They’ve taken more than 350,000 high-resolution underwater photographs of the Douglas DC-4, which is resting on the seafloor roughly 2,000 feet below the surface.
The recent quest to find the Clipper Endeavor was spearheaded by Russ Matthews, an aviation and maritime historian who also serves as the president and co-founder of the nonprofit Air/Sea Heritage Foundation. When he first learned of the wreck, he was “astonished that such an important story had largely faded from public memory,” he says in a statement.
In 2019, he began his search for the long-missing plane. He scoured accident investigation reports and conducted underwater surveys off San Juan, including one in 2022 in partnership with the National Oceanic and Atmospheric Administration.
A few years later, Matthews teamed up with Josh Gates, the host of the Discovery Channel’s “Expedition Unknown,” for an episode that was televised in October 2024. They compiled more clues about the aircraft’s location, including survivor testimony, communications transcripts and a map created by the U.S. Air Force pilots who had witnessed the crash.
This year, they learned that a research ship would be traveling near the Clipper Endeavor’s suspected wreck site. The ship had a high-tech autonomous underwater vehicle nicknamed “Miss Millie” onboard, which provided the team with a rare opportunity to search for the missing plane.
Miss Millie spent roughly 30 hours beneath the waves, methodically scanning the seafloor with its high-resolution sonar. “We did run directly over a shipwreck that nobody knew was there,” Matthews tells the New York Times’ Neil Vigdor. “And it was like, well, that’s interesting, but like we’re looking for a plane, so let’s keep going.”
Then, on June 2, Miss Millie found their target. A subsequent photographic survey revealed that the plane’s landing gear and main cabin windows are still visible. So is the Pan American World Airways logo, as well as part of the “Endeavor” name. The aircraft’s main body is battered, but still largely intact.
The team did not disturb the wreckage. They say they have no plans to retrieve remains (39 bodies were never recovered), per the New York Times. The team is working with the Puerto Rican government to expand protections for the wreck site and create a memorial for the victims.
Pan Am Flight 526A was climbing out of San Juan, Puerto Rico, on April 11, 1952—Good Friday—when two of the plane’s four engines lost power. Pilot John C. Burn quickly headed back toward San Juan, but the large aircraft, which is about the same size as a Boeing 737, began descending rapidly. The crew members dumped fuel to lighten the plane, but Burn was eventually forced to make an emergency landing on the water. The flight lasted less than nine minutes.
All passengers and crew members are believed to have survived the initial crash, but many later drowned. The plane sank in less than three minutes in what became known as “La Tragedia del Viernes Santo,” or “the Good Friday Tragedy.”
At the time, airlines were not required to provide passengers with safety briefings explaining what to do in an emergency. “There was no demonstration of where the exits were, where the flotation devices are,” Gates tells NBC's Drew Weisholtz on Today . “And so in all of that chaos and all that panic, 52 people drowned in and around this plane.”
The deadly crash of Pan Am Flight 526A, however, ushered in a new era of aviation safety regulations, including now-mandatory emergency procedure demonstrations.
“Whether you’re going on vacation, going home for the holidays or you’re a business traveler—every time you set foot on a plane, you owe a debt to what happened to Clipper Endeavor,” Gates adds.
This article was originally published on Smithsonian Magazine. Read the full story here: This 1950s Airplane Disaster Prompted the Flight Safety Demonstrations Passengers Know Today. Searchers Just Found the Wreckage in the Atlantic Ocean © 2026 Smithsonian Institution.
