In May 1939, on the occasion of the First International Aeronautical Journalists’ Congress held in Rome (Guidonia), the prototype was analyzed by a group of Italian and foreign pilots, who appreciated its qualities. The RO57 displayed itself better, in almost all the performances, than Macchi MC200 (the best national single-engine fighter), but shown soon a fault in the weaponry (only two 12.7 mm Breda Safat).