One commonly used separation in these locations is track separation, which states that two aircraft on different tracks to/from a navigational aid must be separated from each other provided at least one is a minimum distance from the navaid. The distance required varies dependent upon how far apart the tracks are. For example, two aircraft on tracks that are 60° apart do not have to be far from the navaid to be clear of each other in comparison to two aircraft whose tracks are 13° apart.