When are runway signs typically used?

Runway signs are primarily utilized to deliver critical information regarding runway numbers and the directions of taxiways. These signs are essential for pilots as they navigate the airport environment, ensuring they are aware of which runway they are about to enter, the direction they need to taxi, and the specific identifiers associated with each runway. This visual information plays a crucial role in maintaining safety and efficiency during ground operations.

The other choices do not accurately reflect the primary function of runway signs. For instance, weight limits for a runway would typically be communicated through different means, such as regulations or NOTAMs, rather than through runway signs. Furthermore, while active runways are vital for operations, runway signs are not exclusively used for marking these; they also relate to taxiways and other relevant information. Similarly, runway lights' positions are indicated through different types of markers and visual cues rather than runway signs. Thus, option A accurately encapsulates the primary purpose of runway signs in the aviation field.