What happens in a runway incursion category C situation?

Answer: B — Separation decreases

In a runway incursion category C situation, separation between aircraft or vehicles on the runway is diminishing, leading to a risk of collision if actions are not taken promptly. This category typically indicates that there is a significant and urgent need for the involved parties to recognize the situation and respond quickly to avoid a potential incident. While other categories may have different characteristics—for example, category A situations often involve immediate collision risk, and category D indicates no potential for a collision—category C specifically highlights that the separation is decreasing. Therefore, it’s essential for everyone operating on or near the runway to be highly vigilant and ready to react to mitigate any risks associated with diminishing separation.