What additional light must WIG craft display in specific situations?

The required additional light for a WIG (Wing-In-Ground) craft in specific situations is a high intensity all-round flashing red light. This signal is crucial because it differentiates a WIG craft from other maritime vessels when it operates in a manner that may not be readily recognizable. The flashing red light serves to alert other vessels to the presence of the WIG craft and indicates its specific operational mode, commonly associated with takeoff or landing phases, where the craft is close to the surface and may not conform to typical vessel navigation patterns.

This safety measure helps prevent collisions and misunderstandings at sea, ensuring that other mariners are aware of the unique characteristics and potential hazards associated with WIG craft operations. The use of high intensity ensures visibility over long distances, especially in conditions where visibility might be reduced.

In contrast, the other options do not serve the same purpose in identifying WIG crafts during those critical operational states. Each of them is typically associated with different types of vessels or scenarios that do not apply to WIG crafts specifically. Thus, the high intensity all-round flashing red light is both a practical and regulatory measure under maritime law for WIG craft.