More Dangerous Osprey

Former Secretary of Defense of United States, Donald Rumsfeld, once called it the world most dangerous military base. In that base, Futenma US Marine Air Base, twenty-four tiltrotor aircraft, MV-22 Osprey, which were as dangerous as dubbed “widow maker,” were deployed in 2013. While Japanese government tried to persuade the people in Okinawa with reasoning of low accidental ratio of Osprey, it is proved that the ratio has gotten higher in a short period.

US Marine Corps categorizes the accident costing $2 million or more or causing death in Class-A severe accident. The ratio of those accidents in 100 thousand hours in flight time is used as a benchmark of its safety standard. Japanese Ministry of Defense announced in October 2012 that the severe accident ratio of Osprey was as low as 1.93, which meant that the aircraft would cause less than two severe accidents during 100 thousand-hour flight.

According a news report of Mainichi Shimbun, Marine Corps revealed that Osprey caused 9 severe accidents after finishing its testing development in October 2003. The flight time of that period was 302,207 hours, which meant that the ratio had risen up to 2.97, reaching 3. That data indicates that the ratio of severe accident became 1.5 times higher than five years ago.

Five years ago, MoD appealed Osprey’s reliability with lower accident ratio than the average of total aircraft accident ratio in Marine Corps, which was 2.45. But, the accident ratio of Osprey, which had been revealed at the end of US fiscal year, was raised up to 2.62. Afterward, Osprey caused two severe accidents in Okinawa last December and in offshore Australia this August. Another accident in Syria last month has further raised the ratio.

US Marine explains that military aircrafts always face potential risk and they are preparing for prevention in every step to keep high standard for safety. “Severe accident ratio is one of the indicators, because the accidents can occur with other reasons like false operation than aircraft itself,” told an officer in MoD. Both governments insist on the safety of Osprey.

Experts indicate structural problem of Osprey. One doctor who had been involved in the analysis of Osprey in Department of Defense warned to Mainichi that complicated structure of Osprey would not allow any trivial mistake. A Japanese military expert supposes that hard exercise caused serious accidents. The high ratio of Osprey’s accident cannot be accepted by the people in Okinawa, who protested deployment of that dangerous aircraft.