Complex sentence: Between 10 February and 20 November 1941 FEAF received 197 additional pilots (141 of them pursuit pilots) but all except 28 were fresh from flight schools and required further individual training, which cut into needed unit tactical training.
Split into simpler sentences: Between 10 February and 20 November 1941 FEAF received 197 additional pilots (141 of them pursuit pilots). All except 28 were fresh from flight schools and required further individual training, which cut into needed unit tactical training.