To maintain desired hovering altitude under no wind conditions, what action is taken?

Maintaining the desired hovering altitude under no wind conditions primarily involves changing the amount of main rotor thrust. When a helicopter hovers, it achieves a balance between the lift generated by the rotor system and the weight of the aircraft. If the helicopter is at a desired altitude, any adjustments to maintain that altitude, especially in static conditions, will require modifications to the rotor thrust.

Increasing the main rotor thrust will enhance lift and allow the helicopter to maintain or gain altitude. Conversely, if less thrust is provided, the helicopter may lose altitude. Therefore, maintaining altitude within this context necessitates direct control over the rotor's lift capabilities, achieved by modifying the amount of main rotor thrust.

This concept is critical in helicopter operations, as it ensures stability and control while hovering, particularly when there are no external forces like wind affecting the helicopter's performance.