When approaching to land, pilots of fixed-wing aircraft must circle to which side if not otherwise directed by the tower?

In standard aviation practices, fixed-wing aircraft are typically required to circle to the left when approaching to land unless otherwise directed by air traffic control. This left-hand pattern is consistent with many airports' traffic patterns and minimizes the risk of conflict with other aircraft that are also entering or departing runways.

The choice to circle left is primarily based on several factors, including visibility for flight crews, the design of many runways, and the need to maintain safe distances from arriving and departing traffic. Left-hand patterns allow pilots to have clearer sightlines of the runway as well as the surrounding traffic, which enhances overall safety during landing operations.

In contrast, circling to the right is less common and may lead to confusion or increased risk, as pilots could be more likely to encounter conflicting traffic. The directions to circle up or down are not applicable in this context, as the standard operational procedures do not include such maneuvers for landing.