Accident Overview
On July 10, 2011, at approximately 16:28 Japan Standard Time, a Cessna 208B, registration JA55DZ, operated by Tokyo Skydiving Club, departed from Honda Airport for a skydiving flight. The aircraft carried 20 people: the captain, a passenger, and 18 skydivers. After the skydivers exited over the airport, the aircraft landed at around 17:10. Following landing, the captain inspected the aircraft and discovered damage to the leading edge of the left horizontal stabilizer. One skydiver sustained slight injuries to both legs.
Flight History
According to the captain's statement, the accident occurred during the eighth flight of the day. After takeoff from Runway 14, the aircraft climbed to about 13,000 feet while turning. The jumpmaster directed the start of the dive, and the first 16 skydivers exited in groups over approximately two minutes. The remaining two skydivers, including Jumper A, requested additional time and altitude. The captain maneuvered the aircraft, making turns and climbing with full engine power, flaps extended, and a pitch angle of about 8°, resulting in a climb rate of about 700 ft/min. The airspeed was approximately 100 knots, higher than the normal 70-80 knots for skydiving operations. Jumper A did not call "power cut" as per standard procedure before exiting. The captain heard a small hitting sound and turned to see Jumper A had already exited.
Jumper A stated that he wore a wingsuit and was scheduled to dive as the last jumper. After the preceding jumper deployed his parachute, Jumper A requested a U-turn and altitude increase. He later lost sight of the preceding jumper and, concerned about distance from the airport, rushed to exit. He recalled feeling sudden pain in both legs immediately after jumping and then began spinning.
Injuries and Damage
The aircraft sustained substantial damage to the left horizontal stabilizer, including large dents on the leading edge and deformation of the top surface. The captain noted that the extent of the dents suggested a serious injury could have occurred, but Jumper A's injury was limited to slight red marks on his legs.
Probable Cause as Determined by Investigation
The Japan Transport Safety Board determined that the accident was highly probable because Jumper A failed to follow the basic established procedure when starting his dive, resulting in both his legs making contact with the left horizontal stabilizer and damaging the airframe. Contributing factors may have included the higher than usual airspeed due to climbing at full engine power, strong airflow around the horizontal stabilizers from the propeller slipstream at full power, and Jumper A's failure to take proper action required when diving in a wingsuit, leading to higher than usual ram-air pressure.