What is a fixed value that should be maintained on final approach?

Maintaining a fixed approach speed on final approach is crucial for several reasons. This speed, which is specified in the aircraft's operating handbook, allows the pilot to ensure safe and controlled flight as the aircraft descends towards the runway. It is essential for achieving the correct lift-to-drag ratio, which helps maintain a stable descent and approach configuration.

Flying at the recommended approach speed also helps prevent stalling by ensuring that the aircraft remains within a safe margin above the stall speed. Furthermore, maintaining this speed allows pilots to make necessary adjustments for wind conditions—such as a strong headwind or tailwind—while ensuring proper control of the aircraft during the critical landing phase.

While the other factors, such as descent rate, altitude above ground level, and heading alignment, are indeed important for a successful landing, they can be adjusted as needed. The approach speed, however, is a fixed value that should remain constant to achieve the desired performance and safety margin.