Shin Meiwa US - 1A The Shin Meiwa PS - 1 and US - 1A ( ) are large STOL aircraft designed for anti - submarine warfare ( ASW ) and air - sea rescue ( SAR ) work respectively . The PS - 1 was a flying boat which carried its own beaching gear on board , while the US - 1A is a true amphibian . Design and development . In 1960 , Shin Meiwa demonstrated a prototype flying boat , the UF - XS , that featured a novel boundary layer control system to provide enhanced STOL performance . The company also built upon its wartime experience ( as Kawanishi ) to refine the Grumman Albatross hull that the aircraft was based on . In 1966 , the JMSDF awarded the company a contract to further develop these ideas into an ASW patrol aircraft . Two prototypes were built under the designation PS - X and flight tests began on October 5 , 1967 , leading to an order for production under the designation PS - 1 in 1969 . Apart from the boundary layer control system ( powered by an independent gas turbine carried in the fuselage ) , the aircraft had a number of other innovative features , including a system to suppress spray during water handling , and directing the exhaust from the aircraft ' s four turboprop engines over its wings to create yet more lift . Between 1971 and 1978 , the JMSDF ordered 21 of these aircraft , and operated them until 1989 when they were phased out and replaced with P - 3 Orion s . The small production run resulted in an extremely high unit - cost for these aircraft , and the programme was politically controversial . The PS - 1 ASW variant carried homing torpedoes , depth charges and 127mm rockets as offensive armament but had no defensive weapons . It was equipped with dipping sonar , which had limited use as it required the aircraft to land on water to deploy . It could also carry up to 20 sonobuoy s . It had a crew of ten : pilot , co - pilot , flight engineer , navigator and six sensor / weapons operators . The PS - 1 had not been in service long before the JMSDF requested the development of a search - and - rescue variant . The deletion of the PS - 1 ' s military equipment allowed for greater fuel capacity , workable landing gear , and rescue equipment . The new variant , the US - 1A , could also quickly be converted for troop - carrying duties . First flown on October 15 , 1974 , it was accepted into service the following year , and eventually 19 aircraft were purchased . From the seventh aircraft on , an uprated version of the original engine was used , but all aircraft were eventually modified to this US - 1A standard . The US - 1A ' s first rescue was from a Greek vessel in 1976 . Between that time and 1999 , US - 1As had been used in over 500 rescues , saving 550 lives . One PS - 1 was experimentally modified for aerial firefighling in 1976 with an internal capacity of of water . With the US - 1A fleet beginning to show its age , the JMSDF attempted to obtain funding for a replacement in the 1990s , but could not obtain enough to develop an entirely new aircraft . Therefore , in 1995 , ShinMaywa began plans for an upgraded version of the US - 1A , the US - 1A " kai " ( US - 1A 改 - " improved US - 1A " ) . This aircraft features numerous aerodynamic refinements , a pressurised hull , and more powerful Rolls - Royce AE 2100 engines . Flight tests began on December 18 , 2003 . The JMSDF purchased up to 14 of these aircraft , around 2007 and entered service as the ShinMaywa US - 2 . Concept aircraft not built . In 1977 Shin Meiwa had several ideas for it ' s STOL flying boat concept on the drawing board but none were ever built . They were the Shin Meiwa LA ( Light Amphibian ) , a 40 passenger light amphibian for inter - island feeder service ; the 400 passenger Shin Meiwa MA ( Medium Amphibian ) ; the Shin Meiwa MS ( Medium Seaplane ) a 300 passenger long range flying boat with its own beaching gear ; and the gargantuan Shin Meiwa GS ( Giant Seaplane ) that has a passenger capacity of an astonishing twelve - hundred ( 1200 ) passangers seated on three decks ! Unlike the Shin Meiwa LA and MA which were like the US - 1 in design the Shin Meiwa MS and GS had it engines located in front of and above the wing like the USAF Boeing YC - 14 to give STOL effect . In the end , none of the four designs got beyond the drawing boards .