The fatal crash of a U.S. Osprey aircraft in Japan last year was caused by a “catastrophic failure” in the gearbox and the pilot’s decision to continue flying despite the malfunction, according to a U.S. Air Force report.
The report states that the Osprey pilot did not have a “sense of urgency” to make an emergency landing despite repeated warnings in the cockpit.
The pilot received an emergency advisory to “Land as Soon as Practical” when the aircraft was still close to mainland Japan and could have diverted to the nearest landing airfield. But the crew continued their planned mission with “limited discussion” of options to divert the flight, according to the report.
That advisory also allows the aircraft commander discretion in continuing the mission, “based on circumstances of the mission and operating environment,” the report states.
The pilot received an emergency advisory about 71 minutes into the flight.
The pilot then decided to divert to Yakushima Airport, located about 60 miles away. The report states that this decision did not indicate “a sense of urgency commensurate” with the seriousness of the condition.
The report suggests that the pilot could have considered other landing locations, “such as islands with helipads, suitable landing terrain on other islands, or runways, such as the one located on Satsuma-IoJima, approximately 36 nautical miles away.”
Once in the vicinity of the Yakushima Airport, the Osprey flew in a “routine box pattern,” rather than declaring an emergency to air traffic control and proceeding with a “straight-in” approach to the runway. This added several additional minutes to the flight, according to the report.
The pilot eventually notified the the airport that they had an emergency but not until four minutes before the “catastrophic failure.” Inadequate risk management by the pilot “substantially contributed” to the crash, the report found.
“While on final approach to Yakushima Airport, at approximately 800 feet above ground level, the left-hand PRGB catastrophically failed, causing sudden asymmetric lift, and forcing the [aircraft] into an immediate left roll, resulting in the aircraft abruptly rolling twice before impacting the water,” it reads.
The Osprey is a hybrid aircraft with both vertical takeoff and landing capabilities. It can operate like a helicopter but can also rotate its propellers mid-flight to cruise faster like a fixed-wing plane.
While its ability to change the way it flies makes the Osprey extremely useful for a variety of missions and operations, the aircraft has faced mechanical and operational issues since its first flight in 1992. It has been involved in multiple accidents, including those in Japan, where it is deployed at both Japanese and U.S. military bases.
Since 1992, there have been more than a dozen Osprey crashes, resulting in the deaths of more than 50 servicemembers.
