An Air Self-Defense Force helicopter involved in a near-collision on Wednesday at Naha Airport in Okinawa had taken off against an order by the air traffic controllers to wait, transport ministry sources said.

At about 1:20 p.m., a Boeing 737 operated by All Nippon Airways with 83 passengers and crew was forced to abort takeoff when the ASDF helicopter crossed in front of it.

The behavior of the CH-47 chopper, which took off because the pilot mistakenly believed the controllers' takeoff clearance directed to a different aircraft was meant for himself, may constitute a possible violation of air traffic control orders, the sources said.

Air traffic controllers then instructed an approaching Japan TransOcean Air Boeing 737 to go around and try landing again. But the flight with 44 people aboard proceeded to land before the ANA plane moved, risking a collision, according to transport ministry officials. The planes came within 400 to 500 meters of one another.

The ANA flight bound for Hokkaido was then canceled, and its passengers took another flight to their destination.

Industry observers said the three minutes before takeoff and eight minutes before landing are the most dangerous time for flights, during which 80 percent of all aircraft accidents take place.

There have been a spate of incidents at airports across the country recently, and many of them are caused by communication trouble between controllers and pilots.

Aviation analyst Kazuki Sugiura said Naha Airport, which has a 3,000-meter runway used by both civilian and SDF aircraft, is a tough one for controllers, because they have to juggle different types of flights and it's busy throughout the day.