On Good Friday, April 11 1952, a Pan American Douglas DC-4 named Clipper Endeavor took off from San Juan in Puerto Rico, bound for New York. On board were 64 passengers including six infants, plus five crew.
The flight lasted less than nine minutes before two engines lost power. Unable to make it back to the airport, the captain ditched the plane in the Atlantic Ocean, roughly 11 miles northwest of San Juan’s Isla Grande Airport.
Remarkably, all 69 people on board survived the impact. What killed 52 of them was what happened afterwards.
The airframe broke apart and began to sink, and in the ensuing chaos, many passengers refused the captain’s order to get out, remaining buckled into their seats. Investigators recorded drowning as the cause for almost all of the deaths.
The pilot told air crash investigators that he had forced some of the passengers into the water. However, the language barrier between the crew and the mostly Puerto Rican passengers had made communication harder – as did their reported fear of sharks in the water.
For 74 years, the wreckage remained hidden under 2,000 feet of water off Puerto Rico’s coast – until an uncrewed underwater vehicle owned by marine survey company Deep Sea Vision located it in June 2026.
As a former commercial airline pilot, the story of this tragedy holds particular interest for me – in particular, the enormous impact it had on how airline safety procedures are still done today. According to Josh Gates, a Discovery Channel presenter who was part of the search team: “It is an accident that fundamentally reshaped aviation as we know it.”
The critical 90 seconds
The US Civil Aeronautics Board’s investigation found that Clipper Endeavor should probably never have taken off. One engine that later failed had shown abnormal fuel readings and metal fragments in its oil the day before.
But the report placed greater weight on what happened after the ditching. There had been no requirement for passengers to be briefed on the plane’s emergency exits, nor to be shown how to use a life vest before a flight over water.
In short, nothing had prepared 64 people for the critical 90 seconds they had to escape the plane before it sank.
As a result of these findings, regulators soon required airlines to keep life vests and rafts accessible to passengers rather than locked away, and to give passengers on extended overwater flights a verbal briefing on life vests, emergency exits and rafts – including demonstrating how to put on a life vest.
The aim was to make sure passengers had already walked through the actions in their minds before panic could override them. A 2018 review of aviation safety research highlighted that many historical air accidents would have resulted in significantly higher survival rates, had every passenger involved read the safety card or watched the crew’s demonstration beforehand.
One apparent example of the importance of passenger safety briefings occurred in January 2009, when Captain Chesley “Sully” Sullenberger ditched US Airways flight 1549 into New York’s Hudson River after a bird strike disabled both engines. All 155 people aboard survived.
However, the official investigation into the incident told a more complicated story than the “Miracle on the Hudson” headlines suggested. About 70% of passengers had not watched any part of the pre-flight briefing, and only around ten had retrieved a life vest themselves.
The evacuation was nonetheless orderly, which investigators credited to the flight crew’s professionalism, the flotation equipment the aircraft was carrying, and ferries reaching survivors within about seven minutes. Clipper Endeavor’s passengers faced almost the same situation decades earlier, with none of that preparation and no one reaching them in time.
Not every incident since the 1952 Pan Am tragedy has ended so fortuitously. Knowing the safety drill is one thing – following it under real pressure is another.
When a hijacked Ethiopian Airlines jet ditched in the Indian Ocean in 1996, killing 125 of the 175 people aboard, the official investigation found that passengers in the economy cabin had inflated their life vests before the aircraft went down.
Crew members had to quickly deflate them and re-brief passengers on the brace position under extraordinary stress. Their instructions were found to have only been given in English, so investigators concluded that some passengers probably hadn’t understood them.
Passenger compliance in an emergency
During my ten years flying Airbus A320s and A330s as a commercial pilot, giving the safety briefing was never my job. That role falls to cabin crew whose professionalism rarely gets the credit it deserves.
The seatbelt sign was mine, though. My voice was the one on the PA reminding passengers to stay buckled in whenever seated – another critical piece of safety advice for as long as the plane is in the air, which Clipper Endeavor’s passengers never received. (If you are not convinced of the seatbelt sign’s importance, read this interview with the passenger who was nearly sucked out of a Ryanair flight recently.)
After each flight, pilots and crew have a debrief that may include discussion of passenger behaviour, particularly if something went wrong during boarding or an emergency. The recurring complaint among cabin crew was about what passengers do the moment an emergency actually starts: reaching for hand luggage instead of leaving it behind.
When an Aeroflot Sukhoi Superjet caught fire after a hard landing in Moscow in 2019, investigators found that passengers retrieving bags from the overhead lockers had probably slowed the evacuation of the burning cabin, contributing to the deaths of 41 people.
A separate study of real emergency evacuations found that half of those involved admitted to attempting to grab a carry-on bag on their way out, making it the most commonly reported obstruction to a fast evacuation.
A 2014 study by aviation safety scientist Brett Molesworth showed that passengers’ recall of safety messages was better if they watched more entertaining demonstrations that used humour or celebrities.
As a result, some airlines now make safety videos both entertaining and informative – such as British Airways dressing more than 40 staff in period costumes for a Regency-style safety film, and Qatar Airways using the American comedian and actor Kevin Hart.
But recall and compliance during a terrifying emergency, when passengers are prone to panic, are two different problems. This is the gap the air travel industry is still striving to solve.
Marco Chan does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
