Accident Overview
On August 18, 2010, a Bell 412EP helicopter registered as JA6796, operated by the Japan Coast Guard, was involved in an accident near Sanagijima, Tadotsu-cho, Nakatado-gun, Kagawa Prefecture, Japan. The helicopter struck overhead wires spanning between Sanagijima and Oshima and subsequently crashed into the sea at approximately 15:10 Japan Standard Time. The aircraft was destroyed, and no fire occurred. All five occupants—the pilot in command, co-pilot, two mechanics, and a radio operator—sustained fatal injuries.
Flight History
The helicopter departed Hiroshima Airport at 13:47 for a patrol flight in the eastern Seto Inland Sea. The flight also served as a demonstration flight, a hulk investigation, and co-pilot captain training. Flight data indicated the aircraft flew at varying altitudes and speeds, conducting maneuvers such as descents, turns, and coastal flights. At 15:08:55, it flew eastward north of Takamijima, then turned left to head westward toward Oshima. At 15:09:25, it flew past the eastern tip of Oshima, then continued south along the coastline at about 227 ft and 100 kts. At 15:10:04, while at the southwestern tip of Oshima making a right turn, the recorded data ends. A witness, the captain of a nearby ferry, reported seeing the helicopter emerge from behind Oshima, then strike the overhead wires with its nose, causing the wires to burst. The helicopter then lowered its nose and fell steeply into the water.
Injuries and Damage
All five persons aboard suffered fatal injuries. The aircraft was destroyed: fuselage and cockpit broken, all four main rotor blades fractured, both engines damaged, tail boom detached, and one tail rotor blade fractured halfway. The accident also severed three overhead wires (Sanagi Lines) owned by Shikoku Electric Power Co., Inc., causing a power outage to 577 households. Power was fully restored by 19:43 the same day.
Aircraft and Personnel Information
The aircraft was a Bell 412EP (serial number 36121), manufactured February 27, 1996, with a valid airworthiness certificate. Total flight time was 6,992 hr 50 min. Its weight and balance at the time of the accident were within allowable limits. Fuel was Jet A-1; lubricant was Mobil Jet Oil. The pilot in command, aged 41, held a commercial pilot certificate with type rating for Bell 212 and a valid Class 1 medical certificate. He had 3,205 hr 03 min total flight time, including 226 hr 10 min on type. The co-pilot, aged 38, also held a commercial pilot certificate with Bell 212 type rating and valid medical certificate, totaling 3,379 hr 55 min flight time, with 23 hr 50 min on type.
Meteorological Conditions
The Takamatsu Local Meteorological Observatory reported generally fine weather in Kagawa Prefecture under a high-pressure system. The witness described the weather as fine with good visibility.