Hãng hàng không Mỹ Piedmont đã mua tới 21 chiếc máy bay của Nhật dùng để chở khách tại Mỹ từ năm 1968, YS-11 đã bay hơn 5 trăm nghìn giờ bay an toàn, ko gặp tai nạn chết người nào, kinh tế và có lãi. Chiếc về hưu cuối cùng kết thúc 14 năm phục vụ với thành tích an toàn tuyệt đối. "It was the right airplane at the right time for the right airline," Piedmont spokeswoman Roslyn Chostner said of the YS11 twin-engine propjet, which made its last trip and ended 14 years of service with a top safety record. The last remaining YS11 was scheduled to fly from Wilmington and Charlotte to Winston-Salem, N.C., officials said. The 58-passenger aircraft will join several other former Piedmont propjets that are for sale. Piedmont officials have not announced a price. The YS11, known for its distinctive whistling sound, was built in Japan. The leader of the design team was Jiro Horikoshi, the designer of the Mitsubishi Zero fighter of World War II. Piedmont once had 21 of the YS11s, and more than 90 percent of its 700 pilots flew the planes. The company was the first in the nation to operate the plane in 1968 in scheduled service. The retirement flight will convert Piedmont to an all-jet airline with a fleet of 43 twin-engine Boeing 737s and 11 three-engine 727s. Records showed that Piedmont's fleet of YS11s totaled more than 500,000 hours of total flight time without a fatal accident. The plane developed a reputation for low maintenance needs and economical fuel use, officials said. Piedmont officials said the YS11 was well suited for many of the smaller airports Piedmont once served because they had relatively short runways and few passengers. The YS11 was safe for such airports, and operated at a profit for Piedmont, Chostner said from company headquarters in Winston-Salem, N.C.