Helicopter Day

What Is Helicopter Day?

Every April 15th is "Helicopter Day" in Japan. The date commemorates the birthday of Leonardo da Vinci (April 15, 1452), who is credited with conceiving the "aerial screw" — a device whose rotating-blade principle anticipated the modern helicopter. The day was established in 1986 by the All Japan Air Transport and Service Association (全日本航空事業連合会) to promote the importance of helicopters and their role as a "second means of air transport" — in disaster rescue, emergency medical services, law enforcement, and broadcasting.

Leonardo da Vinci's Aerial Screw

Among the pages of Leonardo da Vinci's notebooks, a sketch from the late 15th century depicts a "helical air screw" — a device with a large rotating spiral surface designed to "drill" upward through the air. Leonardo never built a prototype, and it could not have flown with the materials and power sources of the time. Still, it is regarded as an early record of the idea of using a rotating surface to generate vertical lift, and is often called the prototype of the helicopter.

The First Practical Helicopters

Helicopters capable of carrying a pilot and flying with stable control appeared only in the 20th century, with practical designs emerging in the late 1930s. Igor Sikorsky's VS-300, first flown in 1939, established the layout of a single main rotor with a small anti-torque tail rotor, which became the template for most modern helicopters.

Helicopters in Japan Today

Helicopters play a critical role in Japan's disaster response. The country's mountainous terrain, many remote islands, frequent earthquakes, typhoons, and floods make aerial rescue operations essential. The Japan Coast Guard, the Self-Defense Forces, and fire departments operate helicopters, and doctor helicopters (ドクターヘリ), which carry emergency medical teams directly to accident scenes, have been in full operation since 2001.

Fun Facts

• Why the tail rotor? Spinning the main rotor makes the body of the helicopter want to turn the opposite way; the small tail rotor counteracts this.
• Where the name comes from: "Helicopter" comes from the Greek "helix" (spiral) and "pteron" (wing).
• Da Vinci's notebooks: Leonardo's scientific and engineering notebooks — now held in collections in Milan, Windsor, Paris, and elsewhere — contain designs for flying machines and many other inventions.