What type of signage uses black letters on a yellow background?

The signage that uses black letters on a yellow background is primarily designed for location identification on an airfield. Location signs provide critical information about where the vehicle is on the airfield, ensuring that pilots, ground handlers, and other operational staff can easily identify their position relative to runways, taxiways, and other important areas. The yellow background with black lettering maximizes visibility and readability, which is vital for safe operations, particularly in various weather conditions or low-light environments.

Runway designation signs typically feature white letters on a red background to indicate runway numbers and direction, while stop signs and yield signs use red colors to signal vehicle operators to take appropriate actions. Thus, the distinctive black lettering on yellow serves a specific purpose related to safety and awareness within the operational context of the airside environment, emphasizing the importance of knowing one's precise location on the airfield.