2023 Miyakojima helicopter crash

The 2023 Miyakojima helicopter crash was an aircraft accident that occurred on April 6, 2023, when a Japan Ground Self-Defense Force Mitsubishi UH-60JA helicopter carrying 10 people, including the commander of the 8th Division, LTG Yuichi Sakamoto, went missing off the coast of Miyako-jima in Okinawa, Japan.

The helicopter, which belonged to the 8th Aviation Squadron of the 8th Division, departed the Miyakojima Sub Base of the Japan Air Self-Defense Force to conduct terrain reconnaissance of the island, with Lt. Gen. Sakamoto and Col. Masaichi Iyoda, commander of JGSDF Camp Miyakojima, among the 10 personnel on board. The helicopter vanished from radar at about 18 km (approx. 11 miles) northwest, just two minutes after making contact with air traffic control at Shimojishima Airport.

Flight

All times are in JST, and in 24-hour notation.

At 15:46 on April 6, 2023, the UH-60JA utility helicopter belonging to the 8th Aviation Squadron of the 8th Division (registration number: 43106, Hereinafter referred to as "helicopter".) departed the Miyakojima Sub Base of the Japan Air Self-Defense Force to conduct terrain reconnaissance of the island, carrying 2 pilots, 2 mechanics and 6 members for the reconnaissance mission (including LTG Yuichi Sakamoto, commander of the 8th Division). At that time, the helicopter communicated with the air traffic control, "We have taken off, will be flying over the coastline." The air traffic controller instructed to change to a different control area, saying, "Contact the air traffic controller in Shimojishima on the next frequency." The helicopter side replied, "Understood." (These are normal communications)

At about 15:51:30, the security camera installed facing east at Karimata Elementary School in Miyakojima captured images of the helicopter flying normally.

At about 15:53:17, the security camera installed facing north at Ikema Elementary and Junior High School in Miyakojima captured the helicopter flying normally. As a result of video analysis of these two school security cameras, it was flying at an altitude of about 195m (about 640 ft) at about 237 km/h (about 147 mph) (UH-60JA's normal cruising speed is about 240 km/h, which is normal flight speed). It seems that the altitude is about 45m higher than the minimum safe altitude stipulated by the Civil Aeronautics Act. In addition, former Lt. Gen. Koichi Isobe (was a helicopter pilot), who confirmed these two videos, said, "It looks like it was flying normally, not in a way that would interfere with the flight."

At about 15:54, the ATC from Shimojishima said, "When you enter the air traffic control area of Shimojishima Airport, contact the Shimojishima ATC frequency." This was the last communication exchange, and there was no communication to report anomalies. It was also around this point that an American tourist, a former sailor of the US Navy, took a video of the helicopter flying at about 400-450 m in altitude along the eastern coast of Ikema Island. At this point, the helicopter was flying straight, the sound was normal and no abnormalities were observed.

At 15:56, the helicopter vanished from the radar in the oceanic airspace about 18 km northwest of Miyako Airport. The helicopter flew almost as planned at an altitude of 150 m (490 ft) until just before it disappeared, and there were no radio communications to notify emergency situations, no emergency transponder signals that are transmitted when a crew member evacuates (Squawk 7700) and no emergency radios were transmitted.

At the time of the accident, the visibility was over 10 km, the weather was clear, the south wind was about 7m, the wave height was about 1m. There was no noticeable development of cumulonimbus clouds, and no lightning was detected. In addition, the depth of water in the sea area around the site is 20m at the shallowest point and 200m at the deepest point. No damage has been confirmed to vessels to area around the site or in the sea area. The last known altitude of the helicopter is the lowest limit of the safe flight altitude stipulated by the Civil Aeronautics Law, which meant there was no legal problem, and it was the usual flight method for the JGSDF helicopters.

After late March 2023, the involved helicopter underwent a special inspection after flying for 50 hours, and as a result of a safety confirmation flight, it was determined that there were no problems with the aircraft. Upon examination of the recovered slider door, it was found that it had been locked, and there was no sign of any attempt to open it in an emergency. There is a high possibility that it was an extremely short time from the occurrence of the anomaly to the crash, and it is possible that the sudden anomaly occurred in about 2 minutes from the last communication to the disappearance from the radar and the crash occurred.

By the night of April 13, a total of 22 fragments and parts of the helicopter had been found and recovered, of which 15 were recovered along the coast and offshore of Irabu Island to the south of the accident site, and 7 were recovered from the sea area to the north of the accident site.

Around 8:30 on April 16, a saturation diver who dived from the submarine rescue ship "Chihaya" found the fuselage of the accident aircraft and five people (which looked like crew members) on the seabed at a depth of 106 m on the north side of the Irabu Island. As of the night of April 16, two of the five people found on the seafloor have been confirmed dead.

The Flight Data Recorder (hereinafter referred to as "FDR") has not been recovered, but this is due to unique reasons to GSDF. In the case of Maritime and Air Self-Defense Force helicopters, which often fly over the ocean, the FDR is attached to the outside of the aircraft, and when it detects a unique impact, it automatically ejects itself and separates from the aircraft, making it easy to find in the event of an accident. It has a strobe light emission and a function to emit a position signal. However, in the case of Ground Self-Defense Force helicopters, since most of their flights are on land, if a small FDR separates in the event of an accident, even if there is a strobe light, it is rather difficult to search in the wilderness or forest, and it is easy for the enemy to take it away. It is installed inside the aircraft and does not have a position transmission function by itself. For these reasons, it is thought that recovery is not possible unless the entire aircraft is found and recovered.

It was also determined that this helicopter was not equipped with emergency floats. According to the Civil Aeronautics Act, the float is required to be installed on "helicopters that fly over water without islands for 30 minutes or more, or that also fly 185 km or more." As government helicopters, the Maritime Self-Defense Force and the Japan Coast Guard equip all aircraft, and the Ground Self-Defense Force equips aircraft deployed in the Okinawa area, but the aircraft of the 8th Division (Kyushu area) is within the normal operation range. It was not equipped because there were no isolated islands that exceeded the provisions stipulated by the Civil Aviation Law. In addition, this flight is also flying via the island in a stepping stone style, which meant there was no legal problem.

Part of the helicopter was recovered on May 2, 2023, along with 6 out of the 10 deceased crew members.