The Spot the Santa's Sleigh rounds off directions to the nearest cardinal and intracardinal directions. This can result in it seeming as though the ISS will be appearing and disappearing in the same direction even though it is traveling across the sky. This typically happens on flyovers with a short window of visibility because the ISS is quickly moving into (or out of) the Earth’s dark shadow where, from our location on the ground, we can’t observe its full pass across the sky.