Yes, planes can fly in any direction, including anti-clockwise, and they do so every day depending on their flight path, traffic patterns, and the prevailing winds. However, there are two contexts where "anti-clockwise" is common. First, in holding patterns, standard patterns are actually "clockwise" (right-hand turns), so an "anti-clockwise" (left-hand) pattern is considered "non-standard" but is frequently used by Air Traffic Control to manage congested airspace. Second, in the Southern Hemisphere, some "round-the-world" travelers choose an anti-clockwise route to better utilize the southern jet streams. On a smaller scale, when an airplane is "circling" an airport to land, the standard "Traffic Pattern" at most airports is actually left-hand (anti-clockwise) turns, meaning the pilot keeps the runway on their left side as they fly around it. This is the global default because most pilots sit in the left seat, providing them with better visibility of the runway during the turn. So, while a plane can fly in any direction, "anti-clockwise" is actually the most common way planes circle an airport to land!