“Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.” This quote has often been attributed to Leonardo da Vinci, but no evidence exists that he ever said it, and for years, mystery had surrounded its true origins.

More recent research has identified the likely author as John H. Secondari, who wrote a 1965 documentary about Leonardo in which the phrase first appears, and which seems to have been confused with the words of the artist himself.

The quote nonetheless summarizes the allure of the airborne experience. However, while flying accidents are statistically uncommon, the experience can occasionally lead to dangers and disappearances, some of which remain unresolved, as a number of notable events have shown. Here is a look at some of the most notable unsolved aviation mysteries of the past.

1. The Missing Balloonist
2. The Mystery Airship Sightings of 1896-7
3. The Disappearance of Amelia Earhart
4. The Cause of Amy Johnson’s Fatal Plane Crash
5. The Identity and Fate of D. B. Cooper

The Missing Balloonist

Matías Pérez was a mid-19th century balloonist who became a notable figure in Cuban history, as well as aviation history in general, due to his ill-fated ascent in Havana in 1856. Pérez had acquired some experience in balloons before this final flight, having made an ascension on three occasions, but things would not go as expected this time.

On the day of his last voyage in the air, he launched his balloon into the sky, only to vanish completely and never be seen again. No further trace of him or his balloon was ever found. It has sometimes been argued as the first recorded instance of a pilot disappearing completely.

What ultimately became of him has never been established, but the nature of his disappearance has made him a key figure in the history of unsolved aviation mysteries.

The Mystery Airship Sightings of 1896-7

In the late 1890s, there was a brief but intense period in which there was a mass of sightings of mysterious airships above the United States. Numerous reports from this time describe claims of large cigar-shaped vessels navigating the night skies, some of which seemed to have powerful lights attached to them.

This was notable because it preceded the widespread availability of this kind of technology on airships, which led people to wonder if something supernatural was causing the effect. The intense interest in this subject led to some amusement in the press, including a cartoonist for the magazine Judge creating a cover which joked that the sightings were due to an overenthusiastic cyclist.

While most of the sightings eventually had a prosaic explanation, a few were never resolved, and curiosity continues on the subject.

The Disappearance of Amelia Earhart

Amelia Earhart is one of the most legendary pilots in the history of aviation: her many accomplishments include her status as the first female aviator to make a continuous transatlantic flight. However, mystery continues to surround her ultimate fate, following her disappearance alongside navigator Fred Noonan during an attempt to become the first female pilot to fly around the whole world.

Earhart and Noonan were last heard from on July 2, on the way to a planned attempt to refuel at Howland Island, before vanishing completely. No trace of her or her companion or their plane has ever been found, and speculation about what happened endures to this day.

However, it is possible there may be a breakthrough in this field in the future. In recent years, a mysterious object thought to be a plane wing was noticed in satellite images of the remote island of Nikumaroro, where it is possible Earhart and Noonan landed during their journey.

The theory is that they may have intended a temporary stop, but lost means to communicate and eventually perished while stranded on the island. This year, a team is scheduled to travel to Nikumaroro to investigate whether the object in the photos could help to solve most of the most enduring unsolved aviation mysteries.

The Cause of Amy Johnson’s Fatal Plane Crash

Amy Johnson was the first woman to fly solo to Australia and was celebrated during her lifetime for her many accomplishments in the field of aviation. But her life and career would come to a tragic end in 1941, in a series of events still veiled in mystery.

While flying her plane over the Thames Estuary in England in snowy conditions on January 5, 1941, her plane crashed into the water, and while a figure was seen in the water calling for help, it was not possible to reach her and her body was never recovered.

What had led the plane to crash would later become a source of great controversy: decades after the fatal flight, a former soldier claimed that he had shot her down under the mistaken impression that she was an enemy pilot (due to her giving the wrong password) and that he only discovered her true identity afterwards. However, this account has never been confirmed by officials, and so mystery surrounds what exactly happened.

The Identity and Fate of D. B. Cooper

One of the most infamous hijackers in the history of aviation is most commonly referred to by a name which was not his own, and whose true identity is still unresolved to this day. The man known as “D. B. Cooper,” who held up Northwest Orient Airlines Flight 305 on November 24, 1971, and demanded a ransom of $200,000.

The man in question had actually bought his ticket using the name Dan Cooper, but this was misreported by the initials DB instead. He ultimately escaped from the plane by parachute before it could land, thus evading the authorities and leaving behind him a startling mystery which remains unsolved, as he was never conclusively identified or tracked down.

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