Lacking the catapult to launch the fighter into the air! The slopped deck was really a very very big flaw but the Soviets has no catapult either! Without the catapult, heavy weight fighter like the Flanker must reduce take off weight that means fee fuel andweapons to be carry! And higly skilled pilot has to risk of failing to take off! Hopefully the succeding carriers has catapults to launch the fighter with fully armed take off weight!