This is believed to be the prototype of the S.55P airliner variant of the S.55, wearing military test serial (MM)97. It joined SAM in June 1928 for use on its Rome - Ostia to Cagliari (Sardinia) line, but is seen here taking off from Lake Maggiore, judging by a similar photo. Photo from: Dan Shumaker collection
This photo was added on 18 November 2023, and has since been viewed 345 times.