Sources differ over the date of the first flight of the PWS-103. According to Cynk, this took place in August 1939, piloted by Zbigniew Żabski. Samolotypolskie cites a later work by Glass as saying neither of two prototypes was finished before the Soviet invasion of northern Poland late in September 1939. In this account they were completed in Poland over the winter then in early 1940 moved to Moscow where they were highly rated by the Soviet pilots who tested them. At least one PWS-103 competed in the 15th All-Polish Gliding Competition held near Moscow later in 1940.