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Maritime Patrol Aircraft: A Japanese Perspective

Keizo Kitagawa
RUSI Defence Systems, 8 December 2014
Aerospace, Maritime Forces
In contrast to Britain's decision to cancel the Nimrod MRA4 in 2010, Japan has developed her own maritime patrol aircraft for the 21st century

As the UK looks to fill the gap in its maritime patrol aircraft (MPA) capability created by the cancellation of the Nimrod MRA4 programme, attention is focused on the United States and Boeing’s P8. However, on the other side of the world, another island nation is still pursuing a domestically developed MPA solution tailored to their specific requirements. Japan is the sixth largest exclusive economic zone (EEZ) in the world and an archipelago of nearly 7000 islands which stretch more than 3,500 km to the east of the Eurasian Continent. MPA help to defend Japan and her interests in many ways. They undertake missions to defend Japan’s territory from infringement or attack, maintain the safety of sea lanes, assist with disaster relief and aid, and generally help maintain the maritime order of the area.

MPA maintains flexibility in ability to transition between situations and its varied roles with its superior mobility (high speed, wide range, and long endurance). MPA can be dispatched to remote maritime areas from mainland Japan, as well as being capable of undertaking surveillance missions. The Government of Japan sees investment in fixed wing MPA to be a necessity both now and going forwards.

Development of the Japanese P-1 MPA started in 2001 at the same time as the production of the XC-2 next generation cargo aircraft. Initially they were independent designs but it was decided to make certain components common to both aircraft in order to reduce development costs. In the unstable and uncertain climate of East Asia after the Cold War, Japan was aware that it required the capability to respond quickly and with flexibility to diverse emergencies which might occur.  Under the circumstances, it became apparent that the Japanese Maritime Self-Defense Forces (JMSDF)’s P-3C Orion MPA’s limited capabilities were not sufficient to satisfy all mission requirements. The maiden flight of XP-1 was made in September 2007, and the production of P-1 started in 2008 and is continued by Kawasaki Heavy Industries (KHI). At present, Japan plans to procure up to 70 P-1 MPAs to replace her aging P-3C fleet.

 P-1 MPA main

Image courtesy of the JMSDF

P-1 is larger than the P-3C, its speed and range have been improved by a factor of between 1.2 and 1.3. As for its onboard systems, improvements have been achieved in all areas, including to the acoustic system. Advanced avionics including the integrated display and head-up display, significantly reduce pilot workload. The mission package consists of acoustic sensors, radar and Combat Direction System (CDS) for central control which requires a crew of eleven to operate. The JMSDF requires a high level of interoperability with the US Navy, and the P-1 is designed to the same standard in this regard as the P-3C it replaces.

Due to the complicated and dangerous circumstances the crew and aircraft may experience in service, the crew and command center must cooperate seamlessly to respond with appropriate force, and so sophisticated C4ISR capabilities were requested.

The P-1 has high performance onboard computer systems, large capacity network, and high speed processing capabilities which can process a large volume of information quickly, resulting in improved mission effectiveness. This ability to transmit correct on-site information, locations and images from the mission location to the command center in large volume transfers at a high speed is indispensable.

To improve warning and surveillance performance, MPAs must be able to identify the nationality, type, configuration and name of a target ship from a great distance. The onboard ISAR (Inverse Synthetic Aperture Radar) can identify ship types whilst the SAR (Synthetic Aperture Radar) can identify moving targets and landforms on land. The high resolution IR/EO (Infrared, Electric Optic) System can then pick up detailed features of the target. The onboard computer can then identify the nationality, type and configuration of a target ship by cross referencing several kinds of electromagnetic waves radiated by a target ship.

The capability to hunt a submerged submarine or one cruising in shallow water was deemed a necessary requirement of MPAs due to the geographical characteristics of the sea areas around Japan. Using its high performance acoustic processing system, which has improved signal processing capability over previous models, the P-1 is able to track modern, almost silent high performance submarines. The high powered radar and advanced IR/ EO systems are necessary to detect a miniaturized periscope breaking the surface of the ocean.

P-1 has a relatively high transit speed in order to reach sea lanes far off-shore. If arrival to the site is delayed after acquiring information about hostile submarine(s), the area to be searched (AOP: Area of Probability) would increase, reducing the probability of detection. Therefore, the P-1 has been designed with high speed capability to arrive at the site in shorter time than the turboprop driven P-3C it replaces. However, the P-1 can also cruise at slow speeds for increased endurance (low fuel consumption) which is necessary for tactical manoeuvres on site.

The P-1’s high altitude performance improves on that of the P-3C in order to allow transit to search areas in any weather conditions. High altitude also increases the coverage of long range radar search operations. The P-1’s has low flying capability is similar to that of the P-3C’s for accurate launching of torpedoes and sono-buoys.

The P-1 was designed with survivability under fire in mind. It has sufficient self-protection capabilities against SAMs (Surface to Air Missiles) from hostile ships or submarines, including mobile SAMs on small unknown boats. Missile warning devices detect approaching hostile missiles and issue warnings to the crew. The P-1 has missile countermeasures such as chaff (electronic deception) and flare (infra-red deception), as well as good flight performance and maneuverability coupled with structural strength sufficient to allow sudden or violent evasive maneuvers. The P-1 is painted in a low visibility color, reducing the chance of visual detection and its infra-red signature has been reduced, making the tracking by missiles difficult. Explosion proof fuel tanks and multi-redundant systems also contribute to the aircrafts survivability against missile strikes.

P-1 carries a variety of high performance weapons on- board against a multitude of threats, giving the aircraft the ability of responding to threats in a timely and successful way, including the use of lethal force if necessary. It is capable of launching Maverick missiles, which have provide accurate target identification capability and can be used even against small maneuverable targets. The P-1 is also equipped with non-lethal but easily recognizable weapons used for warning against unknown boats performing suspicious or illegal behaviors. The P-1’s onboard computer also gives a sophisticated selective attack capability, which selects the most serious threats among many approaching targets.

The P-1 is an environmentally friendly aircraft despite its high performance. Noise levels produced in flight are less than those of the P-3C and the aircraft complies fully with the latest ICAO (International Civil Aviation Organization) regulations for noise. The four turbofan engines of the P-1 employ a variety of technologies pursuing environment friendliness through fuel efficiency and noise reduction technologies.

In summary, the P-1 fixed-wing patrol aircraft is equipped with systems which make the aircraft very capable and suitable for its role as an integral part of Japan’s maritime defence and the maintenance of stability in the region. Under the Three Principles on Transfer of Defence Equipment and Technology adapted on 1st April 2014, the aircraft could prove a fruitful source of international defence and industrial cooperation.

Japan’s decision to develop its own indigenous MPA tailored to its own requirements stands as a marked contrast to the majority of maritime nations looking to chose between a few American and European offerings. As the P1 enters service, many air forces and navies around the world will be watching with interest.

Captain Keizo Kitagawa, JMSDF
Captain Kitagawa is currently Defence Attaché to the UK at the Embassy of Japan


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