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 the 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")