An Airspace Coordination Area is defined as:

• A. A 3D block of airspace in a target area established by the appropriate commander in which friendly aircraft are reasonably safe from friendly surface fires
• B. A 2D map overlay for helicopter routes
• C. An exclusive airspace reserved for air interdiction
• D. An area where airspace is open to all missions without coordination

Answer: (C)

The concept being tested is deconfliction of airspace with ground fires to protect friendly aircraft. An Airspace Coordination Area is a three-dimensional block of airspace established by the appropriate commander within which friendly aircraft are reasonably safe from friendly surface fires. This definition emphasizes not only the vertical and lateral boundaries of the airspace, but also the need for coordination to prevent fratricide and ensure safe operations for air assets operating near ground forces.

The other ideas don’t fit ACA: one describes a two-dimensional map overlay for routes, which isn’t about establishing a 3D protected airspace; another describes exclusive airspace for interdiction, which is a different type of airspace control; and the last describes airspace open to all missions without coordination, which would defeat the purpose of protecting aircrews.