Which system is used on larger cargo and passenger aircraft to compensate for changes in weight distribution along the longitudinal axis?

• A. Horizontal stabilizer system
• B. Vertical stabilizer system
• C. Flaps system
• D. Aileron system

Answer: (A)

When the weight distribution shifts along the airplane’s length, the center of gravity moves forward or aft, changing the pitching moment and how the nose sits in level flight. For large cargo and passenger aircraft, a pitch trim system tied to the horizontal stabilizer is used to counter that moment. By adjusting the horizontal stabilizer’s angle of incidence (or its trim surfaces), the airplane can produce a small, opposite pitching moment to keep the fuselage in the desired attitude with minimal pilot input. This keeps takeoff, cruise, and landing attitudes stable as fuel is burned or payload changes. The vertical stabilizer handles yaw, not pitch; flaps affect lift and drag during certain phases of flight; and the ailerons control roll.