A Maritime Self-Defense Force panel on Tuesday released the results of a probe into an April collision of two helicopters that left eight crew members dead, with the panel’s report suggesting that insufficient coordination by commanders had played a role in the accident.
The report also singled out improper watch procedures by the crew of both SH-60K helicopters, which collided during nighttime training off a remote island near Tokyo on April 20, killing all aboard.
Defense Minister Minoru Kihara told a news conference announcing the report that his ministry had taken the results “very seriously.”
“We will do our utmost to prevent a recurrence, with the determination and resolve that not a single casualty will occur in the future," he said.
At the time of the accident, the anti-submarine training involved three helicopters taking off from two destroyers, where they were based, as part of an inspection to evaluate the skills of the crews.
The report concluded that both helicopters were aware of the other’s presence, but had not performed evasive maneuvers up until the collision, possibly misjudging the distance of the other aircraft.
Both aircraft did not adequately report visual sightings to captains, nor did they properly share information with other crew members on board or receive instructions from the captains to ensure that they were aware of the helicopters’ movements.
One of the helicopters flew straight ahead, according to a map of the flight paths provided by the MSDF, colliding with the left front side of the other, which was in the process of turning clockwise.
The probe also noted that there were two different commanders for the two helicopters, pointing to a failure to communicate between the commanders as leading to an insufficient grasp of the situation.
In a bid to prevent a recurrence, the MSDF plans to better educate crew on nighttime visibility and automatic flight operations, while also emphasizing that altitude control must be unified under the most senior commander.
Information retrieved from both the flight data recorders and the in-flight voice recorders showed the helicopters were within visual range of each other, MSDF Chief of Staff Adm. Ryo Sakai told a separate news conference Tuesday, adding that despite this, there was no clear communication on their distance from each other.
“If the distance had been clearly reported, it might have been possible to avoid the accident,” he said.
Sakai also said that even if the captains or co-pilots in a helicopter are preoccupied, having other members and crew report and keep watch demonstrates the importance of teamwork, the absence of which he believed had been a key issue in the crash.
Training involving several types of patrol helicopters had been suspended following the accident, but was set to resume from Tuesday in phases, the MSDF said. For the time being, this training will only be held during daytime in good visibility, under a single command.
Nighttime training involving multiple commands will resume gradually.
In July 2021, a collision occurred between an MSDF SH-60K and an SH-60J helicopter off the coast of Amami-Oshima in Kagoshima Prefecture during a nighttime training session, though no one was hurt. In August 2017, another SH60J crashed during nighttime training off Aomori Prefecture, resulting in two deaths and leaving one person missing.
Following the 2021 incident, the MSDF implemented preventive measures similar to those it announced Tuesday, including having crew keep watch when multiple helicopters are operating in close proximity with one another and issuing guidelines that aircraft maintain different altitudes.
April's collision also came just over a year after a Ground Self-Defense Force UH-60JA helicopter crashed off Miyako Island in Okinawa Prefecture, killing all 10 people on board — the GSDF’s deadliest accident ever.
It was not clear why the 2021 measures had not been heeded in the April accident, but Sakai hinted that the high-tempo nature of the complicated anti-submarine exercises may have played a role.
“When searching for a submarine, there may be instances when there is no time or space to keep a watchful eye on the situation,” he said.
The SDF has ramped up the pace of sometimes complicated military drills in recent years as the security environment around Japan deteriorates.
Concerns have especially grown about an emergency involving democratic Taiwan, which China considers a renegade province and sits just 110 kilometers from Okinawa’s Yonaguni Island. Top Japanese officials have repeatedly stressed that any conflict over Taiwan would also represent an existential crisis for Tokyo — a hint that it would likely prompt Japan’s involvement.
In such a scenario, years of training — especially in terms of anti-submarine tactics — would provide the SDF with valuable real-world experience, defense experts say.
But the spate of accidents and other incidents involving the SDF has unnerved some critics, who say a shortage of recruits may be creating harsh working conditions that lead to insufficient training.
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