Its main mission is to conduct maritime warning and surveillance activities. The aircraft is dubbed a "submarine killer" because it is capable of detecting and attacking submarines that cannot be perceived with the naked eye.
The Maritime Self-Defense Force has about 10 P-1 planes deployed at Atsugi Air Base in Kanagawa Prefecture. They have so far been operating on a trial basis. Full-scale operations are scheduled to begin during the current fiscal year.
P-1s are priced at about 20 billion yen ($163 million) each. The Defense Ministry plans to procure five per year starting in 2018 and eventually deploy a total of some 70.
On June 25 the MSDF showed a P-1 to the media for the first time, describing its improvements over the P-3, Japan's current mainstay maritime patrol plane.
The P-1 has color radar screens, making it easier to detect and track the movements of suspicious vessels, and its sonobuoy, a device used to gather acoustic data and locate submarines, also offers higher performance.
Moreover, the P-1 is a jet, while the P-3 is a propeller plane, giving the new plane a maximum speed about 30% faster than its predecessor. The P-1 also has a range of about 8,000km, compared with the P-3's approximately 6,600km.
The U.S. military is stepping up its surveillance activities in the South China Sea, flying its P-8 state-of-the-art maritime patrol aircraft, in response to China's moves to build military footholds on reclaimed land.