From the more detailed report in the link:
Ukrainian Airspace Remains Contested
Russia has not achieved air superiority over Ukraine as of March 3. The Ukrainian Air Force continues operating a week after the invasion began, with the Ukrainian General Staff reporting that Ukrainian Su-24s and Su-25s conducted airstrikes in Kyiv, Sumy, Chernihiv, and Kharkiv oblasts in the last 24 hours.[4] Ukrainian air defenses reportedly intercepted a Russian missile targeting Kyiv’s main railway station, which remains packed with refugees, the night of March 2.[5] Russian failures to secure air superiority likely reduce the effectiveness and extent of Russian air and missile attacks, increase the risk to Russian airborne and air assault operations, and force Russian ground combat units to face periodic air attack, likely degrading their operations to some extent. Russia’s failures in the air superiority fight are very surprising; ISW cannot offer any explanations for them at this time.