In aircraft susceptible to tailplane stalls, tailplane icing may be indicated by which symptom?

• A. Loss of elevator effectiveness
• B. Increased elevator authority
• C. Loss of rudder effectiveness
• D. Nose-down tendency on rollout

Answer: (A)

Tailplane icing can cause a stall of the horizontal stabilizer, which reduces the lift and effectiveness of the stabilizer. When the stabilizer stalls, the elevator loses its ability to produce pitch changes, so control inputs on the column produce little or no noticeable change in nose-up or nose-down attitude. This loss of elevator effectiveness is the most direct and reliable indicator of tailplane icing.

An increase in elevator authority would opposite what actually happens with a tailplane stall. Loss of rudder effectiveness points to issues with yaw control rather than pitch control and isn’t the hallmark of tailplane icing. A nose-down tendency on rollout can occur in some scenarios, but it isn’t the specific, defining symptom of tailplane icing like the loss of elevator effectiveness is.