The PA-34 Seneca is an American twin-engined light aircraft, produced by Piper Aircraft since 1971 and remains in production today. The Seneca is primarily used for personal and business flying, but is still used by many flight schools in the U.S. for the training. It was developed as a twin-engined version of the Piper Cherokee Six. The prototype was a Cherokee Six that had wing-mounted engines installed, retaining its nose engine. The prototype was flown as a tri-motor aircraft in the initial stages of the test-flying program. It can hold one crew and five to six passengers depending on the configuration. It is operated by air charter companies and small feeder airlines, and is also used by private individuals and companies. One notable civil operator is the Costa Rican Air Surveillance Service, as well as by the air forces of Brazil, Ecuador, Honduras, Panama, and Serbia.