This story is a collaboration with Biography.com.

Twenty-five years ago, the U.S. mourned the tragic death of John F. Kennedy Jr., who died with his wife, Carolyn Bessette Kennedy, and her sister, Lauren Bessette, in a plane crash off the coast of Martha’s Vineyard, Massachusetts, on July 16, 1999.

Though he chose to focus on a career in publishing instead of following directly in the footsteps of his father, President John F. Kennedy, and his uncles, Robert F. Kennedy and Ted Kennedy, many Americans still saw JFK Jr. as a future political leader, and considered him “the closest thing to homegrown royalty.”

In the aftermath of the plane crash, people flocked to conspiracy theories to explain JFK Jr.’s untimely death. Or they evoked the idea of a “Kennedy curse,” connecting his plane crash to the assassinations of both JFK and RFK.

Instead, the truth is much simpler. It wasn’t a supernatural force or conspiracy that caused John F. Kennedy Jr. to crash his plane—it was a common phenomenon called spatial disorientation, which has affected pilots for over a century.

What Is Spatial Disorientation?

The Federal Aviation Administration (FAA) defines spacial orientation as “our natural ability to maintain our body orientation and/or posture in relation to the surrounding environment at rest and during motion.” Genetically speaking, the FAA says, humans are built to stay properly spatially oriented on the ground; flying in the air, then, is “hostile and unfamiliar to the body,” and it leads to “sensory conflicts that make spatial orientation difficult,” if not impossible, to pull off.

Spatial disorientation can manifest in several ways, including “Aerial Perspective Illusions,” which can trick pilots into up- or down-sloping their descent in a manner ill-suited for the actual runway, and “Autokinetic Illusions,” which “[give] you the impression that a stationary object is moving in front of the airplane’s path,” according to the FAA.

In fact, there’s a chance you’ve experienced a form of spatial disorientation yourself, even if you’ve never flown a plane. Here’s how the FAA explains another potential effect of spatial disorientation, called “Vection Illusions”:

“A common example is when you are stopped at a traffic light in your car and the car next to you edges forward. Your brain interprets this peripheral visual information as though you are moving backwards and makes you apply additional pressure to the brakes. A similar illusion can happen while taxiing an aircraft.”

Five to 10 percent of aviation accidents are due to spatial disorientation, and 90 percent of those accidents are fatal, according to the FAA.

Pilots have been grappling with spatial disorientation for over a century. In 1918, for example, Army Air Corps pilot William C. Ocker famously experienced a graveyard spiral when his plane turned while he thought he was in level flight. While Ocker survived this terrifying experience, it caused him to invent both the gyrocompass and the altitude indicator, and advocate for flying with instrument assistance as opposed to “blind flying.”

“If you experience a visual illusion during flight,” the FAA advises, “have confidence in your instruments and ignore all conflicting signals your body gives you. Accidents usually happen as a result of a pilot’s indecision to rely on the instruments.”

How Did JFK Jr. Crash His Plane?

front page of the daily news dated july 18, 1999, headline
New York Daily News Archive//Getty Images
Front page of the Daily News dated July 18, 1999.

John F. Kennedy Jr. became a symbol of American hope and resilience when he was famously photographed saluting the casket of his late father on the day he turned three years old. Though he was saddled with huge political expectations from a young age, JFK Jr. instead entered the world of magazines, launching George in 1995. The next year, Kennedy married his longtime girlfriend, Carolyn Bessette.

john kennedy junior
Lawrence Schwartzwald//Getty Images
John F. Kennedy Jr. at the opening of Hudson News in Grand Central Station, near a display of George magazine

By 1999, however, JFK Jr. was dealing with problems in both his professional and personal lives. Biography writes:

George was expected to lose nearly $10 million in 1999, according to The Kennedy Curse: Why Tragedy Has Haunted America’s First Family for 150 Years by Edward Klein. Michael Berman, a founding partner in the publication, had recently exited the business, publisher Hachette was reportedly losing interest in the title and Kennedy was looking for alternate sources of financing for the venture.”

George’s struggles were taking a toll on Kennedy and Bessette’s marriage, as she felt the magazine “was receiving most of her husband’s attention.” Two days before their fatal flight, Bessette’s sister, Lauren, arranged for the couple to have lunch and try and rectify things.

Kennedy and Bessette were set to attend a wedding that weekend in Hyannis Port, Massachusetts, and they decided they’d travel with Lauren and drop her off at Martha’s Vineyard along the way. Since JFK Jr. had earned his pilot’s license in 1998, and had just bought a Piper Saratoga light plane a few months before the lunch meeting, he’d fly from Essex County Airport in New Jersey to their destinations.

But there was a problem: At the time, Kennedy was wearing a cast on his ankle from a recent paragliding injury. The day after the lunch meeting, Kennedy went to Lenox Hill Hospital to have it removed, though he was still required to walk on crutches.

On July 16, 1999, John F. Kennedy Jr., Caroline Bessette Kennedy, and Lauren Bessette all arrived at Essex County Airport and boarded Kennedy’s Piper Saratoga. “Coinciding with sunset,” Biography writes, “...the Federal Aviation Administration cleared the plane for takeoff at 8:38 p.m.”

After takeoff, Kennedy checked in with the control tower at Martha’s Vineyard, but when the plane failed to arrive on time, the Piper Saratoga and its passengers were reported missing.

coast guard search for john kennedy jr's plane in 1999
Newsday LLC//Getty Images
A Coast Guard helicopter searches for the remains of JFK Jr’s plane on July 17, 1999.

Search teams discovered fragments of the plane on July 19. The next day, they found debris from the shattered plane scattered across a broad area of the seabed. On July 21, they found and brought ashore the bodies of the three passengers.

Contrary to any conspiracy theories, a report by the U.S. National Transportation Safety Board (NTSB) reconstructed the likely fate of the flight aircraft, determining the aircraft “hit the water at about 9:41 p.m. at Vineyard Haven, Massachusetts.” When investigators examined the plane, they found no evidence of mechanical issues causing the crash, which killed its passengers upon impact.

While the NTSB report mentioned “haze and the dark night” as crash factors, it concluded that the probable cause was “the pilot’s failure to maintain control of the airplane during a descent over water at night, which was a result of spatial disorientation.”

“Within 100 days before the accident,” the NTSB report found, “...the pilot had completed about 50 percent of a formal instrument training course.”

The real story of what killed JFK Jr., laid out within the NTSB’s report, is that of an entirely avoidable death, from something that affects nearly everybody who sits in a cockpit. (As the FAA points out, “most pilots [experience a visual illusion] at one time or another.”)

Pilots can specifically train to spot signs of spatial disorientation, and use simulators like a Barany chair, GYRO, or Virtual Reality Spatial Disorientation Demonstrator to safely experience ground-based sensory illusions and understand what spatial disorientation feels like.

Twenty-five years after the tragic deaths of John F. Kennedy Jr., Carolyn Bessette Kennedy, and Lauren Bessette, spatial disorientation still poses a serious risk to those who take to the skies. But with proper care and training, pilots can effectively manage and mitigate it.

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Michael Natale
News Editor

Michael Natale is the news editor for Best Products, covering a wide range of topics like gifting, lifestyle, pop culture, and more. He has covered pop culture and commerce professionally for over a decade. His past journalistic writing can be found on sites such as Yahoo! and Comic Book Resources, his podcast appearances can be found wherever you get your podcasts, and his fiction can’t be found anywhere, because it’s not particularly good.