What is true about a clearway regarding its control and structure?

A clearway is an area beyond the runway that is primarily designed to provide additional space for an aircraft to abort takeoff or reduce the risk of an incident in case of an engine failure during the takeoff phase.

The correct statement emphasizes that a clearway can be composed of either water or land and must be under the control of the aerodrome authority. This control ensures that the area is properly maintained and managed to mitigate any risks, as the aerodrome authority is responsible for the safe operations of the airfield. Maintaining authority over the clearway is crucial for ensuring that it remains free from obstructions, which is vital for aircraft safety during operations.

The dimensions and gradient mentioned in other options reflect specific regulations and parameters but do not capture the essential characteristic that a clearway must be under the control of the aerodrome authority to function effectively within airspace regulations and safety protocols.