A reduction in anti-torque thrust will cause the tail of a helicopter to:

A reduction in anti-torque thrust affects how the helicopter's tail reacts to torque produced by the main rotor. The main rotor creates a counter-clockwise rotation when viewed from above, which generates torque that tends to rotate the helicopter body in the opposite direction. To counteract this torque and maintain stability, anti-torque thrust is produced by the tail rotor (or other anti-torque systems).

When there is a reduction in anti-torque thrust, the tail rotor is less effective in countering the main rotor's torque. As a result, the body of the helicopter will tend to pivot in the direction of the torque rotation, which is counter-clockwise. This action occurs because the reduction in anti-torque thrust allows the torque effect from the main rotor to dominate, causing the helicopter's nose to turn toward the left when viewed from the pilot's perspective.

This behavior is essential for pilots to understand as it affects helicopter control and responses during various flight maneuvers.