During a runaway trim situation, reducing airspeed to which range will help mitigate control forces?

In a runaway trim situation, reducing airspeed to the range of 110-150 KIAS is effective in mitigating control forces due to several aerodynamic factors.

At lower airspeeds, the control surfaces, such as ailerons and elevators, become less effective. Consequently, at speeds below 110 KIAS, the risk of stall increases, which may not be a safe range for managing the aircraft’s behavior under adverse trim conditions. Additionally, as you approach the lower speed limit, the aircraft becomes increasingly susceptible to turbulence and control difficulties.

On the upper end, maintaining the speed below 150 KIAS ensures that the aircraft remains within a safe maneuvering envelope, allowing for better responsiveness from the flight controls while still avoiding excessive control forces that can occur at higher speeds. The aerodynamic forces acting on the aircraft at this speed range provide an optimal balance of stability and control effectiveness, enabling the pilot to manage the trim situation more safely and effectively.

In summary, the range of 110-150 KIAS strikes the right balance for maintaining manageable control forces during a runaway trim emergency, facilitating a better response to control inputs and increasing the safety margin in this critical situation.