# Pan Am Flight 526A

Pan Am Flight 526A, a Douglas DC-4, took off from San Juan-Isla Grande Airport, Puerto Rico, at 12:11 PM AST on April 11, 1952 on a flight to Idlewild International Airport, New York City with 64 passengers and five crew members on board. Due to inadequate maintenance, engine no. 3 failed after takeoff, followed shortly by engine no. 4. Nine minutes after takeoff, the aircraft ditched in rough seas 18 kilometres (11 mi) NW of San Juan Airport, broke apart and sank after three minutes. Panicking passengers refused to leave the sinking wreck. 52 passengers were killed, and 17 passengers and crew members were rescued by the United States Coast Guard. After this accident, it was recommended to implement pre-flight safety demonstrations for over-water flights.

## Aircraft

The Douglas DC-4 piston aircraft with four propellers had made its first flight in 1945 and had 20,835 airframe hours.

## Accident

On a sunny day with a gentle breeze, Pan Am Flight 526A, a Douglas DC-4 named Clipper Endeavor, took off from San Juan Airport at 12:11 PM on Good Friday of 1952 on a flight to Idlewild Airport, NY (now known as JFK). Sixty-four passengers and five crew members were on board, including Captain John C. Burn, a well-qualified, seasoned pilot, in command.
Just after takeoff, engine no. 3 failed at 350 feet (110 m) and the propeller was feathered (its blades were turned parallel to the direction of flight to avoid drag) by the flight crew. The pilots decided to return to San Juan Airport, reversed their heading, and managed to continue climbing to 550 feet (170 m) when engine no. 4 failed as well. With both engines on the right wing inoperable, the Clipper Endeavor was not able to maintain altitude any longer. Captain Burn declared an in-flight emergency and informed the control tower that he planned to attempt a water landing approximately seven miles NNW off Isla Grande.
Winds of 15 knots (28 km/h; 17 mph) whipped up the sea when the Clipper Endeavor ditched into the Atlantic Ocean north of San Juan at 12:20 PM. The rear fuselage broke off behind the bulkhead of the main cabin and the wreckage sank in less than three minutes. Survivors later reported that many passengers had survived the initial ditching but had panicked because they feared the rough seas and the possibility of sharks and had refused to leave the sinking aircraft to board life rafts.

## Rescue

After having received Captain Burn's emergency transmission, the tower notified the United States Coast Guard (USCG) rescue center and a PBY-5A Catalina flying boat under the command of Lieutenant Ted Rapalus was airborne within six minutes. The USCG's second PBY was undergoing routine maintenance and had the auxiliary power unit (APU) including bilge pump removed. Due to the gravity of the emergency, the PBY was removed from maintenance status and under the command of Lieutenant Commander Ken Bilderback was airborne within 10 minutes. To assist the rescue on the surface, the USCG buoy tender Bramble with medical personnel on board was launched as well. Two SA-16 amphibious aircraft from Ramey Air Force Base, located at the far northwest corner of Puerto Rico, were also dispatched. Together, they were able to rescue 12 passengers and all five crew members from the rough seas.
Bilderback's PBY had 15 survivors on board when it found itself in a dire situation: because of the missing APU and bilge pump, the flying boat had taken on a lot of sea water and had almost no power left to takeoff. The decision was made to transfer the survivors to the Bramble. Sea conditions worsened and after the successful transfer of all but two teenage survivors, Bilderbeck's only options were to either abandon the flying boat or to attempt to taxi it back on the sea to San Juan Harbor. As they passed Fort El Morro and taxied into San Juan Harbor, people lined the shore cheering the rescuers.

## Probable cause

The following causes were found by the investigation:
* inadequate maintenance: engine no. 3 was not changed, leading to its failure immediately subsequent to take-off.
* faulty engine parts
* the pilots' attempt to re-establish a climb without using all available power after the loss of the second engine (engine no. 4). This led to a nose high pitch attitude and rapid decrease of airspeed which settled the aircraft at an altitude too low for an effectual recovery.
In subsequent legal proceedings, Captain Burn was exonerated and the fault turned out to be inadequate maintenance and faulty parts.

## Aftermath

Lieutenant Commander Bilderback was awarded his second Air Medal. His co-pilot, Lieutenant Commander Jack Natwig, received the Silver Lifesaving Medal for jumping into the sea to successfully rescue a young boy. Air crew members Bill Pinkston, Jim Tierney, Peter Eustes, and Raymond Evans were all commended by the Commandant of the USCG for a job well done.
After this accident, it was recommended to brief the passengers about the location and usage of emergency exits and personal flotation devices before flights over open water.
In memory of the lives lost, and honoring the rescuers, a San Juan resident wrote a ballad.
Pan Am later reused the name Clipper Endeavor for both a Boeing 707-321B in 1962 and a Boeing 727-235 in 1980. A Douglas DC-7B was named Clipper Endeavour, using the British spelling.
Wreckage of Clipper Endeavor has yet to be located. A search for the wreckage was featured in an October 2024 episode of Expedition Unknown.