General Authority of Civil Aviation (GACA) Aeronautical Information Publication (AIP) Practice Exam

Under what condition does TAC automatically activate?

1. When thrust difference exceeds 10%

2. When cruising altitude is reached

3. When flaps are deployed

4. During landing only

The correct answer is: When thrust difference exceeds 10%

The correct answer highlights the condition related to the automatic activation of the Thrust Asymmetry Compensation (TAC) system. TAC is designed to enhance control and stability in scenarios where there is an imbalance in engine thrust, commonly caused by a thrust difference between engines. When the thrust difference exceeds a predetermined threshold, specifically set at 10%, the TAC system automatically activates. This activation helps the pilot maintain directional control and compensates for the asymmetric thrust that could potentially lead to undesirable flight characteristics. In contrast, the other scenarios listed do not directly correlate with the automatic activation of TAC. Cruising altitude being reached primarily pertains to the transition of flight phases rather than thrust discrepancy, deploying flaps is primarily an aerodynamic configuration change without direct implications for TAC, and landing, while a critical phase of flight, does not trigger TAC activation in itself unless there is significant thrust asymmetry present. Thus, the emphasis on thrust difference as the trigger for TAC is essential for ensuring safe and stable flight operations.