100 Stories1990 Miyazaki-Nobeoka Commuter Flight

The helicopter plane crash in 1990 is one of those incidents that should never be forgotten.

Until the mid-1980s, business travelers from Tokyo or Osaka to Nobeoka had to take the Shinkansen to Fukuoka and transfer to the Nippo Main Line limited express train, or take the Fuji or Suisei sleeper expresses by rail, or fly to Miyazaki Airport, take a bus from the airport to Minami Miyazaki Station, then take the Nippo Main Line.

At that time, the Nobeoka-Hyuga area had more than 10,000 employees traveling on business and more than 5,000 visitors per year. The distance between Miyazaki and Nobeoka was approximately 100 km, and the travel time from Miyazaki Airport to Nobeoka was approximately 1 hour and 40 minutes by JR or 2 hours and 10 minutes by car. To shorten the travel time, Asahi Kasei established its own helicopter route between Nobeoka and Miyazaki Airport, which began operation in April 1989.

The flight distance was approximately 75 km, and the time required was about 30 minutes, cutting the one-and-a-half-hour trip from Miyazaki to Nobeoka down to one-third of the travel time.

On September 27, 1990, a little more than a year and a half after the start of operations, the aircraft carrying two crew members and eight passengers crashed near the summit of Mount Makishima in Hyuga, killing all on board. The incident occurred while the aircraft was being operated by Hankyu Airlines, which had chartered it to replace an Asahi Kasei helicopter aircraft that was undergoing a routine inspection.

Why did this tragedy occur? The first factor was a sudden change in the weather. Before takeoff, the captain listened to the weather forecast and determined that minimum flight conditions were met, and that the next day the flight would be cancelled due to bad weather, but the captain decided that the current flight was possible. However, the weather was rapidly deteriorating, partly due to Typhoon Gene.

The second factor was that the flight was flown at a low altitude due to the poor weather conditions. The accident investigation report indicated that the aircraft may have descended to check the ground surface, or that the captain may have suffered from spatial disorientation. Spatial disorientation is a condition mainly characterized by a pilot temporarily losing their sense of balance during flight. It is impossible to know in advance whether it will occur.

The accident investigation report by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) states that the cause is presumed to have been caused by flying at an extremely low altitude of around 400 feet, which could have resulted in a collision with a nearby mountain, under conditions of significant visual impairment in the vicinity of the crash site.

Asahi Kasei also conducted a thorough investigation of the accident over a period of about three months, and has summarized the pros and cons of resuming helicopter operations and its future plans, pointing out two problems and pledging to prevent a recurrence.

The first is what could have been done to ensure safe operations; after all, Asahi Kasei routinely operates many plants safely and could have utilized its know-how.

The second is that they changed the contracted company without so much as a second thought. Originally, Japan Air System (JAS) operated and maintained the Aerospatiale aircraft (JA9920) owned by Asahi Kasei. When the aircraft was taken out of service for maintenance or other reasons, JAS was to provide a replacement aircraft. However, at the time of the accident, it was not possible to provide a replacement aircraft, and after a simple screening process, Hankyu Airlines was entrusted with the operation of the aircraft for one month while it was undergoing routine inspections. This was a decision that was made without much thought given to policies and principles.

As a result, the company concluded that it would abandon the resumption of helicopter operations as a matter of safety, as well as due to public perception of the resumption of operations.

After this accident, the company took a new direction in cooperation with local governments to reduce travel time between Miyazaki and Nobeoka. At that time, when the construction of the East Kyushu Expressway was still in its infancy, the company worked to speed up the 83.7 km Nippo Main Line between Nobeoka and Miyazaki by strengthening the track and installing track facilities and tracks for express trains waiting to pass through. In 1996, it was instrumental in opening the Miyazaki Airport Line directly to the passenger terminal at Miyazaki Airport. Also, in 2014, the East Kyushu Expressway was opened.