Gone In 35 Seconds : Spatial Disorientation And The First Fatal F-35 Crash

 F-35A Photo : JASDF

The Lockheed Martin F-35 Lightning II is one of the newest and most advanced tactical fighter that is beginning to populate the air forces of the United States and some of its allies in sufficient numbers to make a difference operationally. Despite having a difficult development cycle which was plagued with everything from cost over-runs to performance issues, the F-35 has a relatively benign safety record and managed to remain crash-free for 12 years since its first flight. That all changed in October 2018 when a US Marine Crops F-35B suffered engine failure and crashed during a routine training flight in South Carolina. Fortunately there were no fatalities as the pilot managed to eject safely.

The first and only fatal crash of the F-35 occurred on 9th April 2019 and it involved a Japan Air Self Defense Force F-35A operating out of Misawa Air Base ( 三沢基地 ). The crash site was the Pacific Ocean some 135km due east of Misawa. The pilot apparently flew the aircraft at high speed into the sea and did not send any signal of distress nor attempted to eject prior to impact. Parts of the wreckage were found scattered over a wide area on the seabed at a depth of 1500m. After 2 months of investigations, the JASDF concluded that spatial disorientation was most likely the cause of the mishap though gravity induced loss of consciousness could also be a remote possibility.

How could an accident like this happen and what is spatial disorientation? Could better pilot training have prevented such an accident?

F-35A 89-8706 Photo : JASDF

Japan's F-35A

The Japanese MOD placed an initial order for 42 F-35A back in Dec 2011 to replace its fleet of ageing F-4EJ Phantoms. 4 would be assembled at Lockheed Martin's Fort Worth plant while the rest would be built at the Mitsubishi Heavy Industries Komaki South F-35 Final Assembly and Check Out ( FACO ) facility in Aichi Prefecture. In those days the unit cost of the F-35A was USD126million or about JPY14billion. JASDF has so far received 13 F-35A and they are assigned to the 302nd Tactical Fighter Squadron of the 3rd Air Wing based at Misawa Air Base. Misawa is located in Aomori Prefecture in the North-eastern region of Japan. Aomori is famous for its apples and also for its scallops farmed in Mutsu Bay.

F-35A 79-8705 at Misawa AB on 2 Nov 2017 for safety checks
 before its trans-Pacific flight to the US. USAF Photo

 

 

JASDF F-35A 79-8705 escorted by a USAF F-16 assigned to the 115th Fighter Wing,
Wisconsin Air National Guard on its maiden voyage across the Pacific on 6 Nov 2017.
Photo : USAF

The Fatal Accident

According to press release information from JASDF ( Japanese only ), the F-35A that crashed had the serial number 79-8705 and production number AX-5. It was the first Japanese-assembled F-35A and it was only unveiled at the Komaki plant on 5th Jun 2017. Its first flight was on 12th Jul 2017. It was flown to Misawa AB on 2 Nov 2017 to prepare for the trans-Pacific flight to the US for final flight testing. This was to ensure all future Japanese assembled F-35s were up to standard. It went into active service on 28th May 2018 with the transitional F-35 squadron, a temporary unit of the JASDF, before the aircrafts were assigned to the 302nd TFS. The 302nd TFS had been operating out of Hyakuri AB for several years and only completed the relocation to Misawa Air Base in March 2019.

The pilot was subsequently revealed as Major Hosomi Akinori ( 細見彰里 ), a 41 year old veteran with 3200 hours of flight experience but only 60 of those hours were type specific for the F-35A. Japanese media stated that this aircraft has the latest Block 3F mission software with full warfighting capability.




F-35A 79-8705 at Nagoya Airport NKM/RJNA on 2 Nov 2017
Photo Yabyansan via flyteam.jp

On that fateful Tuesday evening of 9th April 2019, the sun had set at 1805 hours. Maj Hosomi was the flight leader for a group of four F-35A on routine air combat maneuvering ( ACM ) training over the Pacific Ocean off the coast of Aomori. The formation took off from Misawa Air Base at 1859 hours and proceeded to perform two-on-two ACM training. At 1925 hours Maj Hosomi reported that the two opposing aircrafts had been shot down in the training with the transmission " 21, two kills ", 21 being his call sign. At 1926 hours the F-35A was at an altitude of 31500ft when ground controllers advised the major to make a turn to port and to descend in order to maintain a safe distance from an approaching US military aircraft ( type unspecified ) at 37000ft. Maj Hosomi replied " Affirmative, Roger " and began his turn and descend. Twenty seconds later, upon completing the turn and by then descended to 15500ft, Maj Hosomi transmitted in a calm voice " Roger, Knock it off " ( meaning termination of training ). Information from datalink and ground radar would later reveal that at this stage the F-35A descended with a speed of 900km/h. Within the next 15 seconds, the F-35A would continue its rapid descend from 14500ft with a speed of 1100km/h and then disappeared from the radar screens when it plunged below 1000ft. The time of impact was estimated at 1926 hours 30 seconds.




Plan view ( view from above ).
Red arrow shows path of Hosomi's F-35A.
Green arrow shows passing US military aircraft.
1. 1925hrs  2. 1926hrs  3. 1926hr15s  4. 1926hr30s
Source : JASDF

Side View ( vertical view ) Source JASDF



Spatial representation of F-35A final flight path. JASDF

Search and Rescue

The search and rescue ( SAR ) effort was probably activated the moment team mates and ground control lost contact with the distressed F-35A. JASDF reported that by 1947 hours eleven of their SAR assets were already airborne. At 1950 hours 5 ships and 2 aircrafts from the Maritime Self Defense Force ( JMSDF ) also joined the search effort. At 2145 hours floating debris had been located. Some of these were later recovered by a UH-60J helicopter from the SAR team operating out of Akita at 2210 hours. At 2248 hours the destroyer escort Chikuma was also on site to recover floating debris. The Air Staff had by then ( 2230 hours ) established an accident investigation committee. Eventually US Forces Japan and the Japanese Coast Guard would also chip in with SAR assets. The various units involved in the immediate SAR effort were as follows:

JASDF : 2 x U-125A and 2 x UH-60J Blackhawk
JMSDF : 1 x P-3C Orion and 1 x SH-60J Seahawk and 5 ships
USFJ    : 1 x P-8 Poseidon
JCG      : 3 ships

U-125A SAR Bizjet

UH-60J SAR Helo



Crash site is in the Pacific Ocean 135km east of Misawa AB.
Exact location of the wreckage is kept secret for obvious reasons.

 

Recovery and Salvage

In the week following the crash up to 17th April, multiple P-8A Poseidon Multi-mission Maritime Aircraft and the guided missile destroyer USS Stethem ( DDG-63 ) also joined in the JASDF-led search effort covering some 5000 sq nautical miles in area.

The USN subsequently chartered a commercial dive support and construction vessel, the Van Gogh, to assist in the search. The Singapore-operated Van Gogh with its onboard USN salvage team supported the search efforts of the research vessel Kaimei, owned by the Japan Agency for Marine-Earth Science and Technology ( JAMSTEC ) and the JDS Chiyoda, a submarine rescue tender of the JMSDF. The 5747t Kaimei has sophisticated equipment to conduct high resolution 2D and 3D survey of the seafloor and is equipped with a remotely operated vehicle that can dive to a depth of 3000m.

The USN also deployed the latest version of its cable-controlled undersea recovery vehicle, the CURV-21 and the TPL-25 ( Towed Pinger Locator ) system in the salvage operation. On or after 3rd May, parts of the flight data recorder a.k.a. the black box were recovered. It was however severely damaged and no useful data could be retrieved. Its recovery therefore did not help in the crash investigation. Much of the wreckage were scattered in a wide area under 1500m of seawater.

The Kaimei deep-sea research vessel

The Van Gogh transiting Naha, Okinawa on 16th April 2019.
Credit on photo.

 

TPL-25 is a towed sensor used for locating emergency relocation pingers
 on downed navy and commercial aircraft at a maximum depth of 20000ft.
USN Photo 

The USN finally called off the search and salvage effort on 8th May though the Japanese MOD felt obliged to continue until they too gave up on 4th June, almost 2 months after the crash. Maj Hosomi's body was never found and his death was confirmed by the Japanese MOD on 7th June. Following the crash Japan has grounded its remaining fleet of 12 F-35A and suspended pre-delivery flight tests for the 14th F-35 from MHI's Komaki FACO facility.

Air Crash Investigation

With the paucity of information obtainable from the wreckage, the crash investigators had relied heavily on communications, ground radar tracking and peer-to-peer datalink information from the F-35's Multifunction Advanced Data Link ( MADL ) to reconstruct the unfolding events prior to the fatal accident. They eventually came to the conclusion that it was most likely due to pilot error, specifically spatial disorientation, that caused the crash. Engine failure was possibly ruled out as the aircraft in question was flying quite normally less than a minute before the crash and there were no signs that the pilot found anything amiss and no alarm had been raised regarding any malfunctions. The last radio transmission from the pilot in a calm voice 15 seconds prior to impact also supported the fact that nothing of distress had been detected at that point in time.

The investigators also somehow determined that Maj Hosomi did not attempt to eject from his aircraft as it was barreling towards the surface of the sea and neither did he respond to alerts from the aircraft's warning systems such as the ground proximity warning system.

The execution of several abrupt maneuvers in rapid succession which included turning, rolling and descending could have severely affected his spatial awareness leading to the wrong corrective actions, potential converting a dangerous situation into an irrecoverable one. The final verdict of the investigators named spatial disorientation to be the most likely cause of the fatal crash with gravity -induced loss of consciousness as a remote possibility.

So what is spatial disorientation and what role does it have in aviation disasters? In order to understand spatial disorientation, we need to dwell into realm of aeromedical physiology a little.

 

Introduction to Spatial Disorientation by Hank Caruso
Image : Naval Aviation News

 

Spatial Orientation

Spatial orientation refers to the natural human ability to maintain our body orientation and posture in relation to our physical environment, at rest and during motion. From an evolutionary point of view humans are adapted to maintaining spatial orientation to the ground. Three-dimensional environments encountered during flight or deep diving are unfamiliar to the human body and can create sensory conflicts and illusions that makes spatial orientation difficult or sometimes impossible to achieve.

According to the Federal Aviation Administration ( FAA ), statistics show that between 5 to 10% of all general aviation accidents can be attributed to special disorientation, of which 90% are fatal.

Sensory Systems

Achieving spatial orientation requires the effective perception and interpretation of sensory inputs from the visual, vestibular, proprioceptive and auditory senses.

Visual references provide the dominant sensory information to maintain spatial orientation. This is especially true if our body and / or environment is in motion.

The vestibular system located in the inner ear has two distinct components with the 3 semicircular canals responsible for detecting angular acceleration ( rotational movements ) in 3 different axis corresponding to the pitch, yaw and roll movements of an aircraft while the otolith organs ( utricule and the saccule ) detects linear and gravitational acceleration respectively.

The proprioceptors are sensory receptors located in the muscles, tendons, joints and skin that play a small role in maintaining spatial orientation. They do however give some indication of posture by sensing the relative position of our body parts in relation to each other and by sensing points of physical contact between body parts and the surrounding environment.

Auditory input has the smallest role among all the senses involved in maintaining spatial orientation.

The Federal Aviation Administration videos below may help you understand the functions of the vestibular system.

Vestibular Illusions Leading To Disorientation

Since visual cues are the most important sensory input for maintaining spatial orientation, the loss of a reliable external visual reference point such as the horizon at night or in adverse weather may lead to the vestibular and proprioceptive systems not interpreting the actual motion of the body through space correctly. Here are some of the vestibular illusions that can occur during flight. Somatogyral illusions originate from the semi-circular canals while somatogravic ones originate from the otolith organs :

The Leans ( somatogyral ) - sudden return to level flight after a gradual and prolonged turn that was unnoticed by the pilot

The Graveyard Spin ( somatogyral ) - entering a prolonged ( more than 15 or 20 seconds ) spin intentionally or unintentionally, the pilot gradually loses the sensation of turning and when the turn is corrected feels a strong sensation of turning in the opposite direction. Any attempts to correct this false illusion results in the aircraft returning to spinning in the original direction, all the while losing altitude. Ground impact is inevitable unless this spatial disorientation is recognized early.

The Graveyard Spiral ( somatogyral ) - similar to Graveyard spiral but caused by return to level flight after prolonged intentional or unintentional bank turn.

The Coriolis Illusion ( somatogyral ) - also known as the cross-coupled stimulation, it is a severe tumbling sensation brought about by moving the head out of the plane of rotation, simultaneously stimulating one set of semi-circular canals while deactivating another set. It can happen when the pilots tilts his head upwards, downwards or sideways when the aircraft is turning. It causes a strong and unpleasant sensation of tumbling which often has a rapid onset. The tumbling feeling can be bad enough to cause nausea and the pilot may feel the aircraft pitching, rolling and yawing all at the same time. It can result in the pilot quickly becoming incapacitated by vertigo and losing control of the aircraft. The severity of this phenomenon is a function of the magnitude of the initial turn, the direction of the head movement and the speed at which the head movement is made.

The G-Excess Illusion ( somatogyral ) - a vestibular illusion that can occur even in VFR ( visual flight rules ) conditions. Happens when the aircraft enters a tight turn that puts more than 1G load on it and the pilot looks back at the turn. An illusion of underbank occurs if the head is facing the inside of the turn elevated or if the head is facing the outside of the turn depressed. The pilot can erroneously perceive that the angle of bank and G-load are decreasing. The instinctive reaction to apply more bank could stall the aircraft or result in ground impact and is particularly dangerous in low altitude and high speed operations. Here's a USAF video on the G-Excess illusion.

Inversion Illusion ( somatogravic ) - usually involves high performance aircrafts, a steep ascend followed by a sudden return to level flight causes the illusion of tumbling backwards or being inverted. The pilot invariably respond by lowering the nose of the aircraft which intensifies the illusion.

Head-Up Illusion ( somatogravic ) - sudden forward linear acceleration during level flight creates illusion that the nose of the aircraft is pitching up. The pilot's response is to pitch the nose down. Night take-off from a well-lit airport into a completely dark sky and carrier catapult take-off are examples that can cause this illusion.

Head-Down Illusion ( somatogravic ) - sudden linear deceleration during level flight creates sensation that the aircraft is pitching down. The pilot may then pitch the nose up and if this occurs when the airspeed is already low such as during final approach, a stall may be inevitable.

With so many possible scenarios that can lead to spatial disorientation, I have had a new found respect for aviators, especially those who fly advanced military fighter jets. It should be noted that visual illusions, of which there are just as many compared with vestibular illusions, have yet to be included in the discussion since they are not relevant in the final flight of F-35A 79-8705.

G-Excess Illusion by Hank Caruso
Image : Naval Aviation News

What Could Have Happened

The sky would be dark over the Pacific Ocean off the coast of Misawa by 1926 hours on 9th April 2019. The waxing crescent moon would have been setting and close to the south-western horizon. The ocean surface would have been dark save for a few dim lights from fishing vessels or the occasional commercial vessel transiting through that area. If there were significant cloud cover on that night, it could have made things worse. Therefore one could possibly conclude that there would have been little visual input for Maj Hosomi and his team when they were flying that night. The most important sensory system for maintaining spatial orientation had been removed.

If the flight path diagrams released by the MOD were drawn to scale and were accurate, we can see that Maj Hosomi's F-35 did make some maneuvers in its final 2 minutes of flight that could potentially trigger spatial disorientation. There was the sustained turning which began from 1925 hours when he was directed to descend but at no point was there a sudden return to level flight. There was also an initial rapid descend followed by an even more acute turning rate before the final plunge.

From the communications intercepts, Maj Hosomi was still communicating normally 15 seconds prior to impact. So it is likely that the spatial disorientation could have taken place earlier but went unrecognized by Maj Hosomi or a sudden and highly debilitating event could have taken in the last 15 seconds of flight.

Looking at the flight profile I would say a G-Excess type spatial disorientation could be the most likely illusion encountered by Maj Hosomi. After all, he was turning at relatively low altitudes ( 14500ft and below ) and at very high speed ( in excess of 1100km/h ) in the final 15 seconds of flight. Looking back at the turn at this point in time could trigger the G-Excess phenomenon and if he had responded inappropriately by increasing the angle of bank without a corresponding increase in back pressure on the stick, the result will be a rapid deterioration into a controlled flight into terrain ( CFIT ) situation. There may simply not be enough altitude or time for recovery.

The Coriolis type phenomenon is also possible during the final turn taken by the F-35 as Maj Hosomi could have inadvertently looked up, down or sideways during the turn thus triggering the incapacitating tumbling sensation characteristic of this vestibular illusion. It could be severe enough to make him lose control of the aircraft.

Contributing factors that could have lead to the loss of spatial orientation include fatigue, inclement weather, unexpected change of flight plans, distractions caused by equipment malfunctions, personal time pressures and even the personal attitude of the pilot ( self-confidence ). Many of these factors could be at work on that fateful night.

The waxing crescent moon on 9th April 2019

The waxing crescent moon would be close to the southern horizon
in the constellation of Sagittarius not far from Saturn.
Image : Sky and Telescope 

How To Prevent Spatial Disorientation

The surest way to completely prevent becoming spatially disorientated is to avoid flying altogether. If that's not an option, then experiencing spatial disorientation illusions in a controlled environment such as a Barany chair, a vertigon, or better still a Virtual Reality Spatial Disorientation Demonstrator ( spatial disorientation trainer ) can be important to help raise the awareness of spatial disorientation and to enable the aviator to recognize spatial disorientation early should it occur during flight.

The FAA's advice to avoid flight conditions that may lead to spatial disorientation is sensible but obviously not applicable to military pilots who may have to fly in the most adverse conditions.

That said, if the aviator still find himself or herself caught in a state of spatial disorientation, the most appropriate action would be to disregard one's sensory perception and to trust the flight instruments instead.

In its press release, the Air Staff concluded with separate recommendations for preventing G-LOC and spatial disorientation among F-35 pilots. For the latter, it recommended better pilot education and awareness on spatial disorientation as well as training on spatial disorientation trainer and training on flight simulator.

So let's take a closer look at spatial disorientation trainers and what they can do.

Virtual Reality Spatial Disorientation Demonstrator

The sensation of spatial disorientation cannot be faithfully reproduced in a conventional flight simulator. To experience such vestibular illusions one would need a special spatial disorientation trainer such as those made by the American company ETC Aircrew Training Systems. Such trainers not only enable pilots to experience the feeling of spatial disorientation and learn to recognize some of those illusions, they also train pilots in coping and recovery skills in an interactive environment.




ETC GL-6000 Spatial Disorientation Trainer aka Kraken.
Image : ETC Aircrew Training Systems

ETC makes many different types of air crew training equipment including several models of spatial disorientation trainers. The most advanced of these would be the GL-6000 Kraken - a research grade SD trainer that would set you back USD19million, and the price does not include the facilities you would need to house it. The only commissioned unit belongs to the US Navy and is located at the Captain Ashton Graybiel Acceleration Research Facility at Naval Medical Research Unit Dayton, Wright-Patterson AFB. The Kraken is so amazing it can have sustained motion in 360 degrees over 6 axis - pitch, yaw, roll, vertical, horizontal and planetary. It can reproduce a sustained 3G acceleration and can reproduce the motion forces experienced in not just fixed-wing aircrafts but also rotary, high speed watercrafts, submarines, high-speed land vehicles and more.

Of course not everybody can afford the Kraken or needs the Kraken. The JASDF has been a loyal client of ETC for the past 30 years with its purchase of the Gyrolab GL-1500 basic spatial disorientation trainer in 1989 followed by the purchase of the Gyrolab GL-4000 advanced spatial disorientation trainer in 2006. ETC announced the decision by the Japanese Defense Agency ( as the Ministry of Defense was then known as ) to purchase the GL-4000 in March 2005 and quoted the price at USD 4 million. It was to replace the then more than 15 year old GL-1500.

Gyrolab GL-1500 Basic SD Trainer. Used by JASDF since 1989.
Replaced by the GL-4000.
Image : ETC Aircrew Training Systems

Gyrolab GL-4000 Advanced SD Trainer. Used by JASDF since 2006.
Replaces the older GL-1500.
Image : ETC Aircrew Training Systems

Using its proprietary GYROLAB technology, ETC's spatial disorientation simulators provides the pilot with the most realistic flight experience short of actually flying the aircraft by combining the latest cutting edge flight simulation technology, including simultaneous ± 360 degree motion in pitch, roll, yaw and planetary, with real-world high definition visuals, realistic engine and flight sounds, detailed cockpit with closed loop flight controls and high fidelity flight models. These fixed and rotary flight profiles are flight-realistic and fully automated. Instructors can also create their own flight profiles through a proprietary editor software thereby allowing the trainer to keep pace with changing training requirements throughout its life cycle. ETC claims that the GYROLAB's ± 360 degree motion capability and its planetary motion, which gives it the capability to generate up to 3.0 Gs, makes it the most realistic and effective flight trainer currently available. And since all axes of motion can be used simultaneously, it can accurately reproduce the motion cues that cause pilots to mistake their aircraft position and motion with respect to the earth's surface, an error we call spatial disorientation or 空間識失調 ( Kukan Shiki Shicho ) as the Japanese know it.

Spatial Disorientation - The Scourge

Spatial Disorientation has always been a serious problem affecting military air forces and commercial airlines worldwide, resulting in many lost pilot ( and passenger ) lives and billions of dollars of aircraft losses. ETC estimated that it accounts for about a third of all military aircraft accidents globally.

The situation can only worsen as military aircrafts become increasing more complex and capable with faster acceleration, tighter turns and higher climbing rates. Increasingly challenging flight activities, increased night and inclement weather operations, night vision goggle flight operations all contribute to a greater risk of the occurrence of spatial disorientation.

Even the most experienced pilot can be susceptible to being spatially disorientated as basic human anatomy and physiology dictates our usual response to unusual external stimuli and those illusions, whether visual, vestibular or otherwise will affect the rookie and the veteran in exactly the same way. Having experienced spatial disorientation before will also not confer immunity to its effects in the future. It will however allow the disorientation event to be recognized more readily the next time it is encountered.

The only cost effective way to prevent spatial disorientation in military pilots of high performance jets is through education, by increasing awareness, and through training on a dedicated spatial disorientation trainer. The ultimate aim is to train the pilot to be able to recognize spatial disorientation early enough to apply the necessary coping and recovery response to avert a potential disaster. Awareness and preparedness are the two pillars in preventing spatial disorientation related accidents.

The loss of JASDF's F-35A with its pilot was a tragic accident from which lessons can be learnt. Since the cost of an advanced spatial disorientation trainer like the ETC GYROLAB GL-4000 or the AMST Airfox is miniscule compared to the cost of a modern 4th or 5th generation fighter jet, maybe all current and future F-35 operators should consider channeling more funds and effort in the procurement and the effective use of such training apparatus.

If God had intended us to fly, he would have made us better ears. Remember, 35 seconds, probably less, was all it had taken to destroy a brand new stealth fighter and claim the life of its pilot.

Addendum

In response to reader comment ... Thanks Ax

Although the Automatic Ground Collision Avoidance System ( Auto GCAS * ) has already been successfully installed on the F-16 since 2014 and has been credited with several saves since, the F-35 currently only has an earlier version of the software known as the Manual Ground Collision Avoidance System ( MGCAS ). This will require the pilot to be able to hear, see, process and heed the MGCAS warning and manually fly the aircraft away from the ground. MGCAS will not prevent a ground collision if the pilot is already unconscious or severely incapacitated by spatial disorientation.

The only thing that could have saved Major Hosomi will be an Auto GCAS, which upon failure of a correct response to a ground collision warning, will assume temporary control and engage the autopilot to row the aircraft upright and initiate a 5-G pull, getting the pilot and aircraft out of harm's way. Unfortunately Auto GCAS has yet to be operational on the F-35.

With successful implementation of the Auto GCAS on the F-16, the knowhow and experience allowed the Air Force Research Laboratory at Wright-Patterson AFB to fast-track F-35 Auto GCAS development and testing. Originally slated for F-35 Block 4.3 upgrade in late 2025, all tests for the life-saving technology has been completed in April 2019, and has been recommended for fielding, seven years ahead of schedule.

Meanwhile, work on the Automatic Integrated Collision Avoidance System goes on ...

AFRL's video on Auto GCAS here.

* In Japanese Auto GCAS is known as 自動地表面衝突回避システム

 

 

Automatic Collision Avoidance Technology / Fighter Risk Reduction Program Logo
Image : NASA

Multi-Role Combat Vessel : Singapore's Next Generation Surface Combatant



Source : MINDEF

In the good old days not too long ago, naval vessels were designed, constructed and deployed for specific tasks. A minelayer would do pretty nothing else but lay mines, a corvette would be primarily for escort duties while frigates were responsible for anti-submarine operations and so on and so forth. It was not uncommon for a navy to own multiple asset types corresponding to the various aspects of naval warfare.

However, the increasing complexity of modern day naval operations coupled with escalating procurement costs and shrinking defense budgets have paved the way for the emergence of the multi-role vessel, a multi-tasking ship that can take on various missions on demand.

For the Republic of Singapore Navy ( RSN ), this trend has already been demonstrated in its Formidable-Class stealth frigates which were equipped for anti-surface, anti-submarine and anti-air warfare. The newer Independence-Class littoral mission vessels ( LMV ) took the multi-role concept even further with their modular mission configurable designs and the innate ability to deploy unmanned systems.

With its long serving Victory-Class missile corvettes ( MCV ) close to their end-of-life, the RSN had announced that they will be replaced by a new vessel type known as the Multi-Role Combat Vessel ( MRCV ) by the year 2030. Little had been revealed from the official channels apart from the fact that the MRCV can be mission configured for anything from high-end warfare to security operations and even humanitarian assistance and disaster relief. It will be a mothership of sorts for an entire range of airborne, surface and underwater unmanned systems. Its design takes into consideration the short innovation cycles in unmanned systems and it will be able to take on new capabilities easily as new technology emerges. MINDEF's infographic illustration of the MRCV seem to suggest a frigate-like vessel with stealth features equipped with vertical-launch system and a helicopter deck.

At the recently concluded IMDEX Asia 2019, at least two possible MRCV candidates have emerged, the Crossover 131 Combatant from Damen Shipyards Group and the Vanguard 130 from ST Engineering. These designs offer a first glimpse of how the future MCV replacements might look like and if I read the lines correctly, they scream "destroyers".







Vanguard 130

In conjunction with IMDEX 2019 Singapore's ST Engineering unveiled a new family of surface combatants known as the Vanguard series comprising of five different classes that share common hull forms. From the company brochures : The design concept centers on a single design that can be applied across multiple classes with modular capabilities. It also allows commonalities such as scalable hull forms, machinery and equipment, system and layout designs, standards for outfitting and installation, to be applied across the various vessel classes which can translate to higher cost efficiencies.

Ships from the Vanguard series can be configured as the Vanguard 80 Patrol Vessel, the Vanguard 95 Naval Research and Support Vessel, the Vanguard 105 Offshore Patrol Vessel, the Vanguard 120 Frigate and finally the Vanguard 130 Multi-role Combatant.

Under this multi-role capability profile, the Vanguard series aims to offer highly operable platforms in high states for the stowage and operation of unmanned systems and vehicles for enhanced reach and visibility.

A quick look at the five members of the Vanguard series would tell you it's the Vanguard 130 Multi-role Combatant, the biggest and most capable ship in the series that fits the MRCV description most. At 130 meters it will already be significantly larger than the Formidable-class frigate and it has to be in order to accommodate all those unmanned systems and perhaps even landing crafts and when required, additional personnel such as special forces. A company spokesman mentioned in an interview by Naval News that the Vanguard 130 will be in the 5000 ton range.

Source : ST engineering

 

The Vanguard series. Source : ST engineering

The Damen Crossover 131 Combatant. Source : Damen

Crossover 131 Combatant

The Crossover series of multi-role vessels has been offered by Damen Shipyards Group since 2014. They are very similar in concept with the Vanguard series focusing on producing highly customizable multi-mission capable naval vessels that can at the same time be self-sustaining, self-reliant, and has a high degree of survivability even in high threat environments. Damen claims that its experience in the clever application of a mix of commercial and naval standards and specifications results in the required naval quality and systems characteristics in its end products but yet support costs can be kept low through competitive pricing and the use of commercial off-the-shelf solutions whenever possible.

The entire family comprises of the Crossover 115 Security, the Crossover 123 Fast Security, the Crossover 131 Logistic, the Crossover 131 Amphibious, the Crossover 131 Combatant and the Crossover 139 Fast Combatant. The version that Damen intended to offer for the MRCA competition is the Crossover 131 Combatant. It has a length of 131 meters, a displacement of 5300 tons, a maximum speed of 28 knots, a compliment of between 108 -125 men and the capability to accommodate an additional 128 personnel.

MRCV Likely Key Features

From bits and pieces of information and images here and there, we can now have some idea of how the MRCV might end up resembling. These are of course speculative at best. The project is not even at the RFI stage yet.

5000 ton class
Conventional hull form with helicopter deck for a medium-lift helicopter
Mission deck / well deck for launching landing crafts
Stealth features
Advanced sensor suites - integrated mast with phase array radar, electro-optical sensors
Advanced ship management systems
Advanced weapons suites - ASuW, ASW, AAW
High efficiency in unmanned systems deployment
Multi-mission capable with swappable modules

What kinds of unmanned vehicles are likely to be deployed from the MRCV? ST Engineering's stable of UUV and USV will give us some ideas.



The Mercury Autonomous Underwater Vehicle can map the seabed
for mine detection. Source : ST Engineering



Venus Unmanned Surface Vehicle. Source : ST Engineering

SAAB Skeldar V-200 VTOL UAV. Source : SAAB

Boeing / Insitu Scaneagle UAV which is already equipping the Victory-class MCV.
Source : Boeing

MRCV or DDG

The mission capabilities and dimensions of both the Vanguard 130 and the Crossover 131 Combatant do make them fit the description of a destroyer closer than those of a frigate. In reality though it can be near impossible to distinguish a small destroyer from a large frigate based on features alone.

Calling the next generation Victory-class replacement the Multi-Role Combat Vessel is an accurate functional description and there is absolutely nothing wrong with that. It could however hide the fact that the RSN is quietly upgrading its capabilities in a huge way. This is not at all surprising given the fact that Singapore's neighbours have been expanding their naval fleets in an even bigger manner. For example Indonesia has commissioned two Sigma 10514 stealth frigates within the past 5 years with four more planned. It has also recently placed an order for three more Nagapasa-class submarines from South Korea, on top of the first three that has been delivered or launched. The Malaysian Navy meanwhile will be receiving their Littoral Combat Ships and their Littoral Mission Ships beginning from 2019.

There exists many instances of other navies misrepresenting ship classes to downplay the true capabilities. The Japan Maritime Self-Defense Force classifying the Izumo-class helicopter carrier a helicopter destroyer ( DDH ) is a prime example. Perhaps Singapore is just trying not to fuel the flames of a regional naval arms race further.

And why might the RSN need destroyers? Well to protect the future Joint Multi-Mission Ship, of course. Aircraft / helicopter carriers never operate alone, and I am certain the MRCV will have an important role in a carrier battle group. Tell me I am wrong.

Ozushima : Kaiten's Last Sanctuary

Kaiten Type 1 replica, Kaiten Memorial Museum.

Towards the last years of the Pacific War, with its once powerful Imperial Japanese Navy ( IJN ) close to total annihilation and its maritime supply lines strangled by the unrestricted submarine warfare waged by the US Navy, the Japanese high command resorted to the deployment of various types of suicide weapons in a desperate but futile attempt to reverse the fortunes of war. One of those so called special attack weapons was the Kaiten, also known as the human torpedo, the underwater equivalent of the Kamikaze.

Despite the high human cost, the Kaiten only achieved limited success throughout its short operational history and was largely forgotten after the War. Of the several hundred operational as well as prototype Kaitens produced, only a handful were ever preserved and displayed in museums in Japan and the United States. Fortunately, at least two former Kaiten training bases at Ozushima and Oga escaped the fate of demolition and are today heritage sites where visitors can learn about the tragic history of those special attack units. Between them Ozushima is better known for its Kaiten Memorial Museum and the ruins of the torpedo launching facility.

I visited Ozushima on a cold rainy winter's day on 7th December 2018* and discovered a quiet and desolate island with hills overlooking the surrounding Seto Inland Sea. A somber and sad place befitting to be the last sanctuary of the Kaiten .....

Kaiten In A Nutshell

The Kaiten was essentially a suicide submarine created by modifying a heavy weight torpedo, inserting a compartment to accommodate a human operator to the mid-section and enlarging the warhead. Several could be carried onboard a mothership, usually a fleet type submarine, and they would be launched when a worthwhile enemy vessel was within range. The Kaiten operator would steer his suicide craft underwater towards the target and pop up to periscope depth for a mid-course correction before the final high speed intercept run. It was the brainchild of two naval lieutenants Kuroki Hiroshi and Nishina Sekio.

Kaiten ( 回天 ) literally meant return to the sky or return to heaven but its original meaning in Japanese as envisaged by Kuroki pertained to the reversal of the will of heaven and regaining the edge on the battle front. It was Vice Admiral Omori Sentaro, then director of the Special Attack Division, who named the weapon after the Kaiten Maru ( 回天丸 ), a steam-powered warship which once served in the navy of the Tokugawa shogunate in the final years of the Edo period. The project was top secret and was given the code name Maru Roku Kanamono ( ㊅金物 ), which roughly translates to zero six hardware.

Key to the construction of the Kaiten was the Type 93 ship launched high-speed wakeless torpedo which used compressed oxygen ( instead of air ) as its propellent. Known as the Sanso Gyorai ( 酸素魚雷 oxygen torpedo ) and nicknamed the Long Lance torpedo by western media, it had a high explosive warhead weighing 490kg and was the most advanced torpedo of its time.

Conceptualized as a special attack weapon in late 1943 and approved for trial production by the naval high command in Feb 1944, Kaiten prototypes were quickly tested and readied for mass production by July 1944. That same month special Kaiten base units were also setup and the first Kaiten training base at Ozushima was operational by 1st September. More training bases were subsequently built all over the coastal areas of the Seto Inland Sea and also around Kyushu Island.

The first combat operations took place in Nov 1944 where Kaiten units of the Kikusui strike group successfully sunk the fleet oiler USS Mississinewa at Ulithi Harbour, Caroline Islands. The only other successes were the sinking of an infantry landing craft in Jan 1945 by the Kongo group and the destroyer escort USS Underhill in July 1945 by the Tamon group.

Of all the Kaiten variants, only the Type 1 saw combat operations. Type 2,4,5,6 and 10 only existed as prototypes and were never used operationally. The Type 10 was developed with coastal defense in mind and was the only variant based on the lighter Type 92 torpedo.

In Japanese, the term ningen gyorai ( 人間魚雷 ) or human torpedo, is synonymous with the Kaiten special attack weapon. In fact they are frequently combined like an adjective before a noun - the human torpedo Kaiten ( 人間魚雷回天 ).






Kaiten ( Maru Roku Kanamono Type 1 )
Displacement 8.3 tons Length 14.75m Speed 30 knots
Engine Power 550hp Warhead 1.55 tons
Source:  Kaiten Museum



Where In The World Is Ozushima?

Ozushima ( 大津島 ) is a Y-shaped island lying approximately 10km off the coast of Shunan City in Yamaguchi Prefecture of Japan. Granite extraction and export used to be the main industrial activity providing sustenance to the island. Endowed with sheltered bays which form natural ports and surrounded by shallow seas, it was here that the Imperial Japanese Navy chose to set up its torpedo testing facilities in 1937 and subsequently the first Kaiten training base in 1944. The base infrastructure included command buildings, living quarters, mess hall and kitchen, guard houses, clinic and sickbay, maintenance workshops, storage areas, seaplane hangars, gun placements and bunkers. Several of these military structures including the torpedo testing pier and the hilltop torpedo observation post survived to this day, though in various degrees of dilapidation. In the post-war years a Kaiten monument was erected on a hill overlooking the former base. The Kaiten Memorial Museum was later built adjacent to the monument. It has a collection of more than a thousand artifacts relating to the Kaiten. Today, with the demise of its granite industry and a greying and declining population**, Ozushima markets itself as Kaiten Island, with the hope to lure in tourists keen to discover the obscure history of the Human Torpedo.

Ozushima and Shunan City

Ozushima Kaiten Base. Existing relics 1 Kaiten Museum 2 Stairs of Hell
3 Torpedo Ignition Test Site 4 Hazardous Material Storage
5 Transformer Station 6 Seaplane maintenance area entrance
7 Torpedo observation station 8 Tunnel 9 Torpedo Launching Facility.

Tokuyama Ferry Terminal : Gateway to Ozushima

To get to Ozushima, you will have to find your way to the Tokuyama Ferry Terminal in Shunan City which fortunately is within walking distance from Tokuyama Station, accessible by the Shinkansen bullet train. Return tickets cost ¥710 ( US$6 ) and it takes about 18 minutes to reach the island by the fast ferry.

The ferry terminal is difficult to miss as there is a replica of the Kaiten prominently displayed at the entrance to the parking area. This life sized replica was used to film the Kaiten movie Deguchi no nai umi or The Sea Without Exit in 2006. It looked and felt like the real thing, black, metallic and menacing, complete with the emblem of the Kikusui strike group on both sides of the flow deflector next to the periscope. I could have been fooled if not for the information inscription in front of the Kaiten.

However, instead of just placing the replica next to an ugly old building by the road side in a restrictively narrow area, the Kaiten could have been better displayed on its own perhaps in a small park next to the ferry terminal.

Kaiten Type 1 life-sized replica, Tokuyama Port, Yamaguchi. 

Kaiten replica with Toyoko Inn Tokuyama
and Shinkansen Station in the background.

Inscription explaining the origins and purpose of the Kaiten replica.
 It was used in the 2006 movie Sea Without Exit.

Kaiten Island

The moment you set foot on Ozushima, you would notice that it is extremely quiet with hardly a soul in sight. The single asphalt road that leads away from the pier is almost devoid of vehicular traffic. There is no bus or taxi service on this small island. A huge sign proclaims Ozushima the Island of Kaiten ( 回天の島 kaiten no shima ) and a map at the bottom lists the various points of interest on the island.

Ozushima from the ferry pier.
The building with the green roof marks the site of the former Kaiten base.

Sign reads Welcome to Otsushima - Kaiten Island

Just by the roadside near the Kaiten Island sign is a small monument with the statue of the Buddist goddess Kannon ( 観音 ) and the words Kaiten memorial ( 回天供養 kaiten kuyo ). A small donation box is prominently placed directly in front of the goddess statue. Fresh chrysanthemum flowers adorning the monument indicates regular upkeep by the islanders. I am guessing that Kannon, being the Goddess of Mercy and also being regarded by the people of coastal East Asia as Goddess of the Sea, the protector of fishermen and sailors, must have been the patron saint of the Kaiten operators, perhaps even the entire Japanese Navy.

The roadside Kaiten memorial with the statue of the sea goddess Kannon.

Behind the statue of the goddess and carved into the stone wall are the lyrics of two songs commemorating the Kaiten and the deeds of its operators, " Mother of Kaiten - Human Torpedo " by composer and singer Utagawa Fumiko ( 回天の母～人間魚雷～ ) and " Peace Kannon Folk Song " by Aoyama Rumi ( 平和観音音頭 ). The lyrics of Utagawa's song is also found on the polished stone slab erected beside the Kannon statue.

Lyrics of Utagawa Fumiko's Mother of Kaiten - Human Torpedo
 is found on this stone slab and on the wall behind it.

Lyrics of the Peace Kannon folk song by Aoyama Rumi
on the wall behind the Kannon statue.

I follow the signs and head towards the Kaiten Memorial Museum which should be less than a kilometer from the ferry pier. The path goes past the Ozushima Fureai Center, a campground of sorts but it is understandably empty at this time of the year. It then goes behind a couple of school buildings which are also quiet and unoccupied. A large empty grassy field can be seen beyond the school compound. I will soon learn from a signboard by the path that this is the actual site of the former Ozushima Kaiten Training Base. A long concrete high wall which separates the footpath from the site of the former base still stands to this day. It served to prevent Ozushima islanders from observing the activities on the base when they are walking past the area during the war years.

Ozushima Elementary School was built at the site of the former Kaiten base
 after the War. In its last year of operation in 2015, the school had
only 1 student, 3 teachers and 1 staff member.

This structure beside the main school building is probably the
assembly hall. The field where the torpedo maintenance shed
once stood can be seen in the background.

This school field was the site of the main kaiten base.

 

The partially sealed hazardous material storage area is seen built into the cliff side.
The small structure to the right of the school hall is the old transformer station.

Signboard compares former and current structures where the kaiten base once stood.



Passageway lined with sakura trees leading to Kaiten Museum.
The atmosphere will be very different by late March and early April.

The footpath then becomes steep and ends up at the top of a low hill where the Kaiten Memorial Museum is located. Two granite columns mark the entrance to the long passageway leading to the museum. On both sides of the pavement are two neat rows of stones bearing the names of the deceased Kaiten operators.

A large bronze bell with a long striker can be seen hanging from a shelter in front of the museum building. This the Bell of Peace Prayer ( 平和祈念の鐘 Heiwa Kinen no Kane ). A plaque on the outward facing side of the pillar proclaims it was constructed in 1974 with donations from the Lions Club of Tokuyama. Another plaque on the inward side directly facing the bell bears even more interesting information, all in Japanese only, as usual. It states that the material used to cast the bell included about 100kg of gunmetal ( 砲金 hokin ) from the cartridge cases ( 薬莢 yakkyo ) salvaged from the number 3 turret ( 三番砲塔 sanban hoto ) of the IJN battleship Mutsu ( 陸奥 ). The Mutsu sunk with the loss of 1121 lives after suffering a mysterious internal explosion in the very same turret while moored at the Hashirajima fleet anchorage in June 1943. The anchorage lies within the Inland Sea about 60km east of the Kaiten museum as the crow flies. The bell has a diameter of 90cm, weighs 850kg and is crafted after the famous Uji Byodoin Bell of Kyoto, with embossed designs of celestial figures, lions and Chinese-styled words. On 15th August every year, the anniversary of Japan's surrender during World War II, the bell would be struck by visitors with the hope that the sounds would bring peace to the world and appeasement to the lost souls in the southern seas.



Bell of Peace Prayer with Kaiten monument and Kaiten replica
 in background and ginko leaves.

100kg of gunmetal : The link with Battleship Mutsu

The Kaiten Monument

Behind the Bell of Peace Prayer lies the Kaiten Monument, a monolithic greyish granite structure of about 2 meters in height with an altar in front of it and flanked on both sides by stone slabs carved full with words. The plaque on the left lists the submarines lost or sunk during Kaiten operations giving details such as vessel name, operating base, departure date, wreckage site, captain's name and numbers of sailors who perished with the submarine. For example the last entry read : I-165 Submarine, departed Hikari Base 15th June 1945, lost east of the Marianas, captain Ono Yasushi with 104 crew members. Of the 32 submarines involved in Kaiten operations, 8 were lost. The plaque on the right bears the names of all the Kaiten operators who had lost their lives during training or actual combat.

Kaiten Monument



Kaiten Monument overlooking the Seto Inland Sea.

List of submarines and submariners lost during Kaiten operations 

 

List of 145 Kaiten operators and maintenance personnel
 killed during operations or training.

The location of the monument is almost at the edge of a cliff overlooking the Shin Ozushima Ferry Terminal, its breakwaters and the Seto Inland Sea beyond. By this time of the year the trees have mostly shed their leaves leaving bare branches pointing forlornly skywards. The cloudy and rainy weather helps make an already bleak atmosphere even more depressing. I wonder if this despondent feeling was how the Kaiten operators felt before their final departure from Ozushima.

View of the bleak Inland Sea and leafless sakura tree
on a cold winter's day from behind the Kaiten Monument.



Kaiten Type 1 Replica

A life-sized Kaiten Type 1 replica can be seen next to the Kaiten Monument in front of the museum building. Just like the replica at Tokushima Ferry Terminal, it features the emblem of the Kikusui strike group on its flow deflectors. The fact that the Kaiten Museum does not even have a real Kaiten specimen and has to rely on a replica for display is telling of the very small numbers that were preserved after the War. Then the priority was the de-establishment of the armed services, disarming, demobilization and repatriation. Probably very little thought or room was left for the preservation of war relics and anything that could be scrapped would be scrapped. After all, much raw materials were required for the reconstruction and rehabilitation of a war torn nation. By the time the Japanese society has again prospered and the trauma of war has somewhat faded to the extend that the general populace can embrace the idea of commemorating the war dead, most of the artifacts are already lost or forgotten.

As far as I am aware, the only complete Kaiten specimens in Japan can be found in the Yushukan War Museum of the Yasukuni Shrine ( Type 1 ) and the Kure Maritime Museum a.k.a. Yamato Museum (  Type 10 ). In addition, Yushukan has the hull of a Type 4 and the History and Folklore Museum of Yamaguchi has the hull of a Type 2.




Kaiten replica and sakura tree next to monument



Kaiten replica with museum courtyard behind



Kaiten replica with museum behind

The Kaiten Memorial Museum

The idea of a memorial museum was first mooted in 1962 during a kaiten interest group meet in Tokyo. The intended purpose of the museum was to collect, preserve and display artifacts belonging to the deceased kaiten operators. Funding campaign for the construction of the museum began in 1965 and a total of 19.62 million yen was collected. The museum opened its doors in Nov 1968.

Among its collections were more than a thousand items including letters, last wills, photographs and uniforms. One of the most remarkable exhibit was a replica of Kuroki and Higuchi's last testament written on the inner wall of their sunken kaiten before they died of asphyxiation from oxygen depletion. It was a routine training mission on the evening of 6th Sep 1944 that went terribly wrong with the Kaiten stuck in the muddy seabed after an unexpected dive. Trapped under 18 meters of water without much hope of being rescued, the two officers were giving a detailed account of what went wrong and were even suggesting improvements for subsequent models. The sunken kaiten was only located the next day by which time both officers were dead. Kuroki was four days from his 23rd birthday.

Replica of Kuroki and Higuchi's last testament.
Source : Kaiten Memorial Museum

After 30 years in operation, the museum underwent a major renovation in 1998 at a cost of 47.33 million yen. A section of the Kaiten hull used to film the 2006 Kaiten movie Deguchi no nai Umi is displayed in front of a wall full of photographs of deceased Kaiten pilots. Because the museum has a no photography policy, I did not take any photographs when I was inside the museum.

The normal entrance fee is JPY300 ( about US$3 ) for adults but the museum will waive admission fee on two occasions every year. The 15th of August is the anniversary of the surrender of Japan during WWII and on this day visitors will strike the Bell of Peace in the museum's courtyard. Also on the second Sunday of  every November where a memorial ceremony is held in front of the Kaiten Monument. In recent years the number of visitors to the museum hover between 12000 to 16000 annually.

Admission ticket to Kaiten Museum dated 2018 Dec 7th.

Kaiten Tunnels And Launching Pier

Apart from the Kaiten Memorial Museum, the other major attractions of Ozushima are the ruins of the torpedo testing and kaiten launching pier as well as the tunnels that connect it to the main base.

By 1937, weapons engineers producing the Type 93 Long Lance torpedo at the Kure Arsenal had wanted better test facilities to replace the existing one at Dainyu. Ozushima was selected because it could provide a wider and longer test range. The pier to launch the torpedoes was made of steel reinforced concrete and was completed in 1939 at a cost of 830000 yen. It has 2 levels with cranes and 2 launch bays. Construction of its foundations required the use of 8 caissons and another 5 for the foundations of the passageway. The main structure has a height of 10m, length of 12m, width of 7.5m and a draft of 7.5m. Its estimated weight was 700 tons. Before the tunnels were built, portions of the coastal cliffs were hacked away to build a path over rocky outcrops so that the torpedoes could be hauled to the pier from the maintenance workshops. Construction of the tunnels with rail tracks made the transfer much easier.

The tunnel measure about 250 meters and the entrance is not far from the Ozushima Elementary School. At present the rail tracks have been paved over and even the walls of the tunnel looks coated very neatly with fresh concrete. At the mid-point the tunnel widens and has a side opening to the sea where the Kaiten launching pier could be seen not far away. This section of the tunnel also has old photographs of the Kaiten and its operators and audio explanations of the Kaiten's history. The tunnel ends in front of the Kaiten launching pier and a concrete connecting path brings the visitor to the pier.

The tunnel entrance.

Rail tracks are paved over. Wall have been replastered.

Side opening to the sea

Seaward view of tunnel side opening

Mid-portion of tunnel with photo gallery

Tunnel exit and link way to the Torpedo Launching Pier.

The Kaiten base at Ozushima was officially opened on 1st Sep 1944 and training commenced just 4 days later. The torpedo launching pier was then used to launch Kaitens for their training practice in the sea. The internal torpedo launching bays within the structure were designed to accommodate the Type 93 torpedo with a diameter of 61cm. They were too narrow to launch the kaiten which had a diameter of 1 meter. Instead, the kaitens were hoisted into the water from the side of the concrete pier by cranes. The rusted remnants of such a crane can still be seen at the edge of the pier to this day. Note that embarkation for combat operations do not take place at this pier. Instead, other piers over at the main base were used.

Currently, the torpedo launching bays and the upper level of the pier are out of bounds and fenced up. A signboard explains about the Type 93 torpedo. A granite marker stands near the beginning of the link way to the pier and proclaims it the ruins of the torpedo launch site.

Because it is the only surviving structure for Kaiten training built during World War II in the whole of Japan, it is deemed a war heritage and it was conferred the Heritage Award by the Japan Society of Civil Engineers ( JSCE ) in 2006. Here is the JSCE explanatory note to its selection in Japanese.

Sign at exit of tunnel proclaims the area
the Torpedo Launching Facility Relic

The Type 93 Torpedo Launching Facility and Kaiten Training Relic

The two storey concrete structure with two launch bays behind the fence.

Signboard explains the origins of the torpedo test site

These bays are for launching the 610mm Type 93 torpedoes.
The Kaiten has a 1000mm diameter and would not fit.

Remnants of the foundation of the Kaiten hoist at the side of the pier

Torpedo Observation Station

On a hilltop overlooking the sea to the west lies the ruins of the torpedo observation post ( 魚雷見張所 gyorai miharisho  ). A fairly strenuous climb through a bamboo forest is required before reaching this site. It is a single storey building by the cliff with large windows to observe torpedo firing during the War. All its windows are now gone and only the window frames remained. The walls are bare and a few wires dangle from the ceilings, with the electric devices they power long gone. This ruin is generally quite free from graffiti and relatively clean.

Signboard explains about the torpedo observation station

Rear view of the dilapidated building 

The building has a commanding view of the surrounding seas

Bare, doorless and windowless but still standing after 8 decades.

An anti-aircraft gun placement site is located to the north of the museum but I did not have time to explore. It was supposed to have consisted of a 150cm search light, one single barreled 13mm anti-aircraft gun and 3 twin-barreled 12.7mm guns to provide the Kaiten base with some protection against air attack. It will have to wait for another visit to the island in the future.






I-58 with Kaiten Human Torpedoes on deck.
Box art from Tamiya.

The Legacy

The Human Torpedo Kaiten was a suicide weapon system unlike any other and unique to the Imperial Japanese Navy. It never quite achieved the success and notoriety of its aerial counterpart, the Kamikaze Special Attack. The only reason that it did not result in more deaths apart from the several hundred operators and submariners who died during combat operations was because the end of the War came swiftly. All Kaiten operations ceased by 15th Aug 1945 with the unconditioned surrender of Japan. Though they did not manage to turn the tide of war and save their country, the sacrifices of these young men may not have been entirely in vain so long as the message of peace is passed on to the future generations.

Today, 75 years on, the world might have forgotten about the Kaiten. However, in the quiet backwaters of the Seto Inland Sea, Ozushima continues to bear silent witness to this tragic legacy which happened so many years ago. Its schools might be closed, its population might be greying and dying, its industries might be gone, but here at Ozushima the Kaiten endures ...


* The day after my visit to Alley Karasukojima in Kure.
* 7th December is also the eve of the anniversary of the Pacific War to the Japanese because of time zone differences.

** In 2017 the population of Ozushima was 275. Of these 78.9% were above the age of 65.