During approach, the use of which mode with the flight director or autopilot is not permitted?

• A. Speed Mode
• B. Altitude Hold
• C. Heading Hold
• D. Vertical Speed

Answer: (A)

The key idea is that approach requires following a precise vertical path to the runway, typically the glide slope. Speed mode focuses on reaching a target airspeed by commanding pitch to raise or lower the nose, which can fight the glide slope and lead to an unstable or mis-tracked approach. On approach, you want the autopilot/flight director to manage vertical guidance, while airspeed is kept under control separately (often with autothrottle or thrust adjustments). That’s why engaging Speed mode during approach is not appropriate. Altitude Hold would keep you at a fixed altitude and prevent the necessary descent, and Heading Hold doesn’t provide the needed vertical guidance either. Vertical Speed is the mode that allows you to descend toward the glide slope while keeping speed managed, making it the appropriate choice for approach.