A comparative analysis has shown MV-22 Osprey aircraft to be deployed to Okinawa later this year have been involved in more accidents among nine planes operated by the U.S. Marine Corps.

The U.S. military categorizes aircraft accidents into three groups: Class A cases involve fatalities or more than $2 million worth of damages, Class B accidents cause injuries resulting in long-term disabilities or damages of between $500,000 and $2 million, while Class C accidents result in minor injuries or less than $500,000 in damages.

According to data compiled by the marines, nine Class B accidents were reported between October 2001 and July 2012 for all nine aircraft, with an average frequency of 2.07 incidents per 100,000 hours of flying time. The rate for tilt-rotor MV-22s, however, came to 2.85 — some 38 percent higher than the overall average. Meanwhile, an average of 10.46 Class C accidents were found to have involved Ospreys during the same period, a 1.3-fold spike compared to overall rate of 4.58.

Four MV-22 Class A accidents also were reported, a frequency of 1.93 cases. This was lower than the 2.45 average for the nine.