Approach speed refers to the speed at which an aircraft descends toward the runway during landing. It is a critical factor in aviation, as it affects the aircraft's stability and control. Pilots must calculate the appropriate approach speed based on various factors, including aircraft weight, weather conditions, and runway length. Maintaining the correct approach speed helps ensure a safe landing. If the speed is too high, the aircraft may overshoot the runway; if too low, it risks stalling. Pilots use instruments and guidelines to determine the ideal approach speed for each landing scenario, ensuring a smooth and safe touchdown.