Sabena airliners which were augmented and later replaced by Douglas DC-6Bs. The DC-4s also restarted the airline's traditional route to the Belgian Congo. Sabena was the first airline to introduce transatlantic schedules from the north of England, when one of its DC-6Bs inaugurated the Brussels-Manchester-New York route on 28 October 1953. The Convair 240 was introduced in 1949 to partially replace the DC-3s that until then had flown most European services. As of 1956, improved Convair 440 "Metropolitan" twins began replacing the Convair 240 twins and were used successfully well into the 1960s between European regional destinations. In 1957, the long-range
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.