Kansai International Airport Opening Day

What Is Kansai International Airport Opening Day?

Every September 4th is also "Kansai International Airport Opening Day" (関西国際空港開港記念日, Kansai Kokusai Kūkō Kaikō Kinenbi) in Japan. On September 4, 1994, Kansai International Airport (関西国際空港, Kansai International Airport or KIX) opened on a purpose-built artificial island in Osaka Bay, about 5 kilometers off the Senshū coast — regarded as Japan's first 24-hour airport and the world's first offshore airport built entirely on a man-made island (Nagasaki Airport, often called the first offshore airport, was built by expanding an existing island). The airport replaced Itami Airport for international flights and provided the Kansai region with modern long-haul international aviation capacity.

An Airport Built on the Sea

Kansai International Airport's construction on a purpose-built artificial island was driven by the impossibility of expanding existing airports in the densely populated Osaka region while maintaining 24-hour operations. The first-phase island, covering about 515 hectares, was built by reclaiming deep water with soft clay beds in Osaka Bay, creating land where none had existed. The first phase is often said to have cost around ¥1.5 trillion (estimates vary), and the island has continued to settle into the soft seabed since opening.

Renzo Piano's Terminal

The airport's main terminal building was designed by Italian architect Renzo Piano — a glass and steel structure about 1.7 kilometers long. Its distinctive curved roof is designed to guide the flow of air through the vast departure hall.

Fun Facts

• Island sinking: The first-phase island sank by about 50 cm a year around the time of opening, but the rate has gradually slowed to roughly 5 cm a year by 2025. The settling is caused by compression of the soft seabed under the island's weight.
• Typhoon Jebi 2018: Typhoon Jebi in September 2018 caused severe damage to Kansai Airport — temporarily closing the facility when a tanker ship broke free of its moorings and struck the connecting bridge, stranding about 7,800 passengers and staff on the island overnight. The incident highlighted the vulnerability of an island airport to extreme weather events.