What does "negative control input" mean in glider flight?

In the context of glider flight, "negative control input" refers to inputs that lead to undesirable flight characteristics. This term can be understood as any pilot action or maneuvering that negatively affects the glider's stability, performance, or trajectory. For instance, if a pilot inadvertently over-controls the aircraft or makes abrupt movements, it can result in loss of altitude, increased drag, or other issues that compromise safe flight operations. Therefore, recognizing negative control inputs is crucial for maintaining proper handling and ensuring the glider remains within safe flying parameters.

The other options represent different aspects of flight control but do not align with the definition of negative control input. Actions that cause the glider to gain altitude or supportive inputs for gaining speed would be considered positive inputs. Similarly, commands that stabilize the flight path imply active corrective measures rather than actions leading to undesirable characteristics. Understanding this distinction is vital for pilots striving for proficient glider operation.