The designer of the aircraft was Giovanni Casiraghi, an experienced engineer who had worked in the US from 1927 to 1936. On the basis of his experience he designed a radically new aeroplane. The P.108 was an all-metal low wing bomber with a retractable under-carriage. During the Air Ministry official requirement of 1939, it won the "Regia Aeronautica"s contract for a new bomber over the CANT Z.1014 as it became obvious that the other competitors could not deliver useful numbers of aircraft to the Italian Royal Air Force before the mid-1940s.