What does the phrase "black square, you're there" refer to?

The phrase "black square, you're there" is associated with location signs. This phrase commonly refers to the black square that can be found on many airport location signs indicating the location of the viewer on a map. These signs are intended to help individuals quickly identify their position within the airport, ensuring they can navigate to their desired destination effectively. Location signs are critical in airports and other large facilities for passenger orientation, helping users understand where they are in relation to nearby services and gates. The other options may relate to elements of aviation and airport operation but do not specifically capture the essence of this phrase as it pertains to identifying a location.