In a busy port, a pilot does not decide how to guide a ship by its size alone. She first checks the available channel depth and the current water level. She then considers wind, current, and the vessel's ability to turn. A route that is deep enough may still be unsuitable if a strong crosswind makes the entrance unsafe. Conversely, a difficult entrance at one time may become manageable when conditions change. The checks do not produce a collection of independent facts that can simply be added together. Some establish whether an option is possible at all; others distinguish among options that remain. This order matters because an attractive advantage, such as a shorter route, cannot compensate for a condition that makes the passage physically unsafe. Good judgment identifies such constraints before optimizing convenience.