The name of the airliner models corresponds to a very precise nomenclature adopted by European and American manufacturers. Boeing only swears by the 7 to name its aircraft.
Comac has made 9 its favorite number, as indicated by the name of its only aircraft, the C919. The letter C refers to China. The 9 is a symbol of eternity: the number has the same pronunciation (“jiŭ”) as the term “long duration”. The A318, A319 and A321 single-aisle aircraft are the exception to the rule because their design is close to that of the A320. These models differ from each other mainly in their capacity and therefore in their size and mass. The aircraft with a capacity of 120 to 160 seats was first marketed by the Canadian Bombardier under the name CS100; it took the name A220 when the program was bought by Airbus in 2020. If the second number chronologically designates the model of the series, the last number is identical to the first simply to create symmetry and be more memorable.