Sabena served by the airline. Sabena used landplanes for its Congo operations and a program of aerodrome construction was initiated in the Congo. This was finished in 1926 and Sabena immediately began flights within the Belgian colony, the main route being Boma-Léopoldville-Élisabethville, a 2,288 km (1,422 mi) route over dense jungle. First, flights were operated with De Havilland DH.50s, although these were quickly replaced by the larger Handley Page W.8f which had three engines and offered ten seats. By 1931 Sabena's fleet, including the aircraft used on the Congo network, totalled 43 aircraft. Its mainstay type was the Fokker F.VIIB with
Sabena Flight 503 communication was cut off. The aircraft had crashed somewhere in the mountains of Rieti, Italy North-East of Rome and was now missing. Sabena itself got notified about the missing aircraft that same night at 23:15 but would not make an official statement until the morning of the following day. The airplane had crashed somewhere in the mountains of Rieti, Italy North East of Rome which were known for being difficult to access and also lay in a nature reserve where wolves roamed. The Italians immediately started a search and rescue mission to locate the missing aircraft and rescue its occupants.