A navigational scan was a type of scan which was performed when a starship was moved. The scan helped the helmsman to intervene and lay a new course to avoid collisions with interstellar phenomena or inorganic matter.
In 2369, moments after the runabout used by Captain Picard, Deanna Troi, Data, and Geordi La Forge experienced a collision with several temporal fragments, Picard gave the order to move away from these fragments. La Forge performed a navigational scan and displayed the result, that they were surrounded by many more temporal fragments. (TNG: "Timescape")