Flights of Su-27 and Su-27UB in the 831 fighter brigade of the Ukrainian air force. July 24, 2020. The City Of Mirgorod. Ukrainian air force has 2 brigades equipped with Su-27s. This is the above-mentioned 831 and 39 fighter brigade in Ozernoye. Each brigade have 2 squadrons. The total number of Su-27s in Ukraine is about 50 machines and of those, approximately 33-35 are in flight conditions. Work is underway on a light upgrade. The upgraded aircraft are marked Su-27P1M, Su-27S1M and Su-27UB1M, respectively.