A Pan Am Plane Vanished Off Puerto Rico in 1952. It Took 74 Years to Find It 2,000 Feet Underwater

On 4/11/1952, Pan American World Airways Flight 526A, the Douglas DC-4 known as the Clipper Endeavor, ditched into the Atlantic shortly after takeoff from San Juan when two of its four engines failed. Sixty-nine people were aboard, and while every passenger made it through the initial impact, only 17 people were rescued before the aircraft sank, leaving 52 dead in what locals remember as the “Good Friday tragedy.” On 6/2/2026, an autonomous underwater vehicle running high-resolution sonar located the wreck nearly 2,000 feet down about five miles off Puerto Rico’s northern coast, a find Air/Sea Heritage Foundation made with Deep Sea Vision that Discovery later announced on 7/21/2026. “We are all stunned and elated by this discovery yet also humbled to remember what happened in that place so long ago,” said Russ Matthews, the nonprofit’s president and co-founder.

Some stories never really end, they just sink below the surface and wait. This summer, a team using autonomous robotics and high-resolution sonar located a missing piece of American aviation history off Puerto Rico. The find is sobering, but also clarifying: it ties a single, devastating flight to the safety rituals most of us barely notice today.

A deadly crash near San Juan in 1952

On April 11, 1952, Pan American World Airways Flight 526A, a Douglas DC-4 “Clipper Endeavor”, ditched into the Atlantic shortly after taking off from San Juan when 2 of its 4 engines failed. All 69 people aboard survived the initial impact, but rescue came too slowly. In the end, 52 people died, with only 17 rescued before the aircraft sank, per 69 people aboard.

The tragedy is remembered locally as the “Good Friday tragedy,” and it left a personal imprint on survivors. The flight’s captain, John Burn, survived, and his son Gray Burn, a 58-year-old private pilot, has described how his late father carried the memory for decades.

How the wreck was found 74 years later

On June 2, 2026, searchers located the wreckage using an autonomous underwater vehicle equipped with high-resolution sonar. The plane was resting nearly 2,000 feet underwater, roughly 5 miles off Puerto Rico’s northern coast, as nearly 2,000 feet describes it.

The mission was run by the Air/Sea Heritage Foundation in partnership with Deep Sea Vision. Identification hinged on the detached tail section and fuselage, and on the blunt proof you can still see in the data: Pan Am branding visible on the wreckage across a survey of more than 350,000 photographs.

Robotics, sonar, and a nonprofit’s playbook

The Air/Sea Heritage Foundation is a nonprofit based in Boise, Idaho, and it has been building a repeatable method for deep-water searches using autonomous systems, according to its Boise, Idaho nonprofit profile. One report put the AUV’s cost between $10 million and $12 million, though the overall operation’s price tag has not been consistently detailed across coverage.

Even the hunt’s pacing is debated: some accounts suggest the wreck appeared on the first pass, while others describe nearly 30 passes before the key returns showed up.

What this changes, and what it preserves

When the discovery was publicly announced on July 21, 2026, foundation president and co-founder Russ Matthews tried to hold both sides of the moment: “We are all stunned and elated by this discovery yet also humbled to remember what happened in that place so long ago.”

The crash helped spur reforms that now feel inseparable from flying, including preflight passenger safety briefings on life vests, rafts, and emergency exits. After locating the wreck, the foundation said it is working with Puerto Rico to protect the site and pursue a memorial, per July 21, 2026.