JASDF F-35A Crash Due to “Spatial Disorganization”

Kai Huang - 2B Computer
Posted on: June 26, 2019

On 9 April 2019, a Japan Air Self-Defense Force F-35A crashed into the northern Pacific Ocean during a night training exercise. While debris from the crash was found quickly after the military became aware of the incident, it did not answer any questions about the cause. How could an experienced pilot with over 3000 flight hours crash one of the most sophisticated modern aircraft? In the wake of the crash, all 12 of the other F-35’s in service with Japan’s armed forces were grounded, and the future of Japan’s F-35 program put into question.

The crash has a profound impact on not just the Japanese Armed Forces but also the entire F-35 program as a whole. Under the new Japanese defense plan unveiled at the end of last year, Japan is on track to purchase 105 F-35A models for the Air Self-Defense Force, as well as 42 F-35B models for the Maritime SelfDefense Force. The total order makes Japan the largest foreign operator of the F-35. Should the crash be attributed to an engineering fault or a mechanical failure, it is likely that the order would be faced with much scrutiny and possible pushback.

On 10 June 2019, the Japanese Ministry of Defense released information provided by the flight data recorder. The pilot, Maj. Akinori Hosomi, had been communicating with ground controllers about 15 seconds prior to the crash. None of the transmissions up to the crash had any sense of urgency and indicated that Hosomi had no knowledge whatsoever of his upcoming fate. The flight data showed during the final messages that the plane was descending at a rate of over 1000 feet per second, at an altitude of no more than 16000 feet.

The conclusion from the Ministry of Defense is that Hosomi encountered
spatial disorientation.

Spatial disorientation is defined as “a situation where the pilot cannot sense correctly the position, attitude, altitude, or the motion of an airplane”. The JASDF is not new to such incidents, and was the focus of a 2009 study, which concluded that 12% of all Japanese military air accidents were a result of the phenomenon. While the F-35 has a plethora of sensors and displays that are intended to alleviate such issues, the presentation of the information is much different than that of previous Japanese fighters. While previous generation jets tended to have most of their information on dashboard
displays, the F-35’s highly advanced helmet provides the pilot with a headsup display. As this technology is new to the JASDF, it is not unlikely that the pilot may not have been familiar enough with this system to notice his fatal descent.

Defense Minister Takeshi Iwaya stated that the training program for Japanese F-35 pilots will now include extended training on how to deal with spatial disorientation. As for the grounded JASDF F-35 fleet, their electrical and mechanical systems will undergo thorough inspections and returned to service after consent has been given by local communities. Nothing will change pertaining to the future F-35 orders.

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