 Complete the following phrase:  The airline was established in April 1971, and started operations in 1975. It was formed as Société de Transports Aériens du Burundi, and adopted the present name in June 1975. The airline began operations a fleet of two Douglas DC-3s followed by two De Havilland DHC-6 Twin Otter and a Sud Caravelle III in 1980. The 1996 