What technique is being used when the pilot flies in a straight line between two briefed checkpoints during manned aerial CBRN surveillance?

In the context of manned aerial CBRN surveillance, the technique described is known as a course leg. This term refers to the segment of flight between two defined checkpoints where the aircraft maintains a straight trajectory, allowing for systematic observation and data collection over a designated area. By flying directly between these checkpoints, the pilot can ensure that all areas of interest are thoroughly monitored during surveillance operations. This technique is particularly useful in allowing for efficient and organized reconnaissance, ensuring that critical points are not overlooked, and providing a clear path for the flight operation.

The other options, while related to navigation and operational techniques, do not accurately describe the specific action of flying in a straight line between checkpoints. For example, a point usually refers to a specific location rather than a segment of flight. A route signifies a broader path consisting of multiple segments rather than the direct method employed in a course leg. Terrain features pertain to physical structures or formations on the ground that could be used for navigation but do not specifically relate to the technique of maintaining a straight course between precise checkpoints.