What is the primary operational mode of a Wing-In-Ground craft?

The primary operational mode of a Wing-In-Ground craft is to operate in close proximity to the surface. This type of craft is designed to take advantage of the ground effect, which is a phenomenon that occurs when an aircraft flies close to a surface, leading to increased lift and reduced drag. By flying in this mode, the craft can maintain a high level of efficiency and maneuverability, as the ground effect enhances its aerodynamic performance.

Hovering, flying at high altitudes, or traveling under the water do not utilize the unique benefits offered by the ground effect, which is crucial for the efficient operation of a Wing-In-Ground craft. As such, operating close to the surface maximizes the craft's capabilities and is essential for its design and functionality.