The Saunders ST-27 Regional Airliner was built in the 1970s by the Canadian Saunders Aircraft Company in Gimli, Manitoba, Designed as a conversion of the earlier de Havilland Heron, the ST-27 was the most radical DH Heron conversion program, featuring two Pratt & Whitney Canada PT6 turboprops and a stretched fuselage. Despite its promise as a regional airliner, the project collapsed when Manitoba government funding was withdrawn. Using 13 surplus de Havilland Herons, Saunders created a conversion with some engineering input from Aviation Traders (Engineering). The remanufactured design was based on a stretched fuselage to accommodate 23 passengers, a lengthened nose to fit a radar, reshaped vertical tail (also increased in size) and two Pratt and Whitney PT6A turboprops replacing the original four Gipsy Queen piston engines, along with other minor changes.
The photo source unknown. The airline "ACES"
Mr. Botero and Mr. Peñaloza, considered pioneers in the early days of Colombian commercial aviation, had tried several times to establish a commuter service between Manizales and Bogotá. With the support and capital of the new partners from Medellín, they embarked on the successful enterprise that would be ACES (Aerolíneas Centrales de Colombia), a company that would earn the respect of its competition and the love of its customers. The airline began service in 1972 with Saunders ST-27 aircraft for the routes Medellín-Bogotá and Manizales-Bogotá, and soon became a major player in the Colombian market.