Which of the following is NOT a function of runway designation signs?

Runway designation signs serve several important functions in aviation, all aimed at ensuring safety and efficient traffic management on the airfield. The primary function of these signs is to indicate the runway number, which helps pilots identify which runway they are approaching or using during takeoff and landing. This is crucial for navigating an airport's layout accurately.

Another significant role is to signify the beginning of a runway. This allows pilots to recognize where the usable runway commences, ensuring that they prepare appropriately for takeoff and landing operations.

Additionally, runway designation signs assist in indicating the landing direction, which informs pilots of the orientation and the way in which they are expected to approach the runway for landing, contributing to safe operational practices.

However, providing aircraft location on taxiways falls under the purview of different types of signs, specifically taxiway location signs. These signs are designed to help pilots determine their position on the airport's taxiway system, rather than the functions fulfilled by runway designation signs. Therefore, this choice does not align with the functions associated with runway designation signs.