The Japanese Ground Self-Defense Force (GSDF) revealed that human error was to blame for the October 27 mishap involving a V-22 Osprey tiltrotor aircraft during Japan-US joint exercises.
The incident occurred at Camp Yonaguni on Yonaguni Island, one of Japan’s westernmost territories. As the Osprey attempted to take off, its left wing struck the ground, damaging the aircraft. Fortunately, none of the 16 personnel aboard, including three US Marines, were injured.
The GSDF’s report identified pilot error as the primary cause. Specifically, the failure to activate a crucial control—referred to as the “interim power switch”—led to insufficient engine power during the takeoff attempt. This oversight, compounded by other factors, caused the aircraft’s wing to collide with the ground.
According to the GSDF, the interim power switch is a critical safety mechanism that boosts engine power during takeoff. Standard procedures mandate that the switch be engaged between starting the engine and takeoff. The investigation revealed that the pilot neglected this step, compromising the aircraft’s ability to maintain stability and sufficient lift.
Complicating matters, the pilot reportedly failed to properly control the Osprey when it was close to the ground, leading to a destabilizing side-to-side motion. The report also cited an increased passenger load—caused by the last-minute arrival of additional personnel—as a factor that heightened the pilot’s workload, contributing to the oversight.
Following the incident, Japan grounded its fleet of 17 Osprey aircraft to ensure safety while investigating the root cause of the mishap. Meanwhile, a team of US Marines was dispatched to Yonaguni to assist in evaluating the aircraft’s condition and explore feasible recovery options. The damaged Osprey remains stationed at Yonaguni, awaiting further action.
Enhanced Training Protocols: Pilots and copilots will now undergo comprehensive pre-takeoff operations training
- Simulations replicating various in-flight scenarios.
- Hands-on exercises focused on managing power-loss emergencies.
- Theoretical lectures and real-flight practice sessions.
- Visual Reminders: The interim power switch will be marked with prominent visual indicators to serve as a reminder during pre-takeoff checks.
- Emergency Response Enhancements: The GSDF is introducing a detailed emergency response plan that will include guidance from commanding officers throughout training and operations.
These steps are part of a broader effort to strengthen pilot proficiency and reduce human error, particularly during high-pressure situations like disaster-response exercises.
The Osprey’s unique tiltrotor design—combining the vertical lift capability of a helicopter with the speed and range of a fixed-wing aircraft—has made it an essential asset for military operations. Its versatility allows it to perform tasks in areas inaccessible to traditional fixed-wing planes.
However, this cutting-edge design comes with significant risks. Since its maiden flight in 1989, the Osprey has been plagued by a series of safety issues, many stemming from its complex gearbox system. These recurring problems have led to a long history of accidents, earning the aircraft its grim moniker: “the widow-maker.”
The October 27 incident is the latest in a string of setbacks for the Osprey. Last year, on November 29, an Air Force Special Operations Command Osprey crashed off Yakushima, an island south of Kyushu in southern Japan, killing all eight personnel aboard.
The crash marked the deadliest Air Force incident since 2018 and was one of four fatal Osprey accidents within a two-year span, contributing to a cumulative death toll of 20 US service members since March 2022.
The Yakushima crash prompted both the US and Japanese militaries to ground their Osprey fleets between December and March while safety reviews were conducted.
- Marine Corps: Approximately 350 units.
- Air Force: Around 50 units.
- Navy: About 30 units.
Despite its operational importance, the aircraft’s safety record has sparked concerns within both US and Japanese defense circles. Japan’s acquisition of the Osprey—part of a broader strategy to enhance its military capabilities in response to regional threats—has been met with skepticism, especially following high-profile accidents.
The October 27 mishap highlights the complexities of Japan-US defense cooperation. Yonaguni Island, where the incident occurred, is strategically significant due to its proximity to Taiwan and contested waters in the East China Sea. Joint exercises in the region aim to bolster interoperability between Japanese and US forces, a critical component of their alliance amid growing security challenges.
While the damaged Osprey has temporarily grounded Japan’s fleet, both nations remain committed to ensuring the aircraft’s safety and operational reliability.
The GSDF’s investigation and subsequent reforms reflect a broader recognition of the need to address human factors in aviation safety. While the V-22 Osprey continues to face scrutiny, the lessons learned from incidents like the Yonaguni mishap may pave the way for improved protocols and training standards.
For now, the damaged Osprey on Yonaguni serves as a stark reminder of the challenges posed by advanced military technology and the enduring importance of rigorous operational discipline.
