What are "V-speeds" in aviation?

V-speeds are specific reference speeds that are critical for the operation and performance of an aircraft. These speeds provide pilots with essential information regarding the aircraft’s handling characteristics and performance in various phases of flight. Each V-speed has a unique designation and significance, such as V1, the takeoff decision speed; Vr, the rotation speed for takeoff; and V2, the takeoff safety speed.

Understanding these speeds helps pilots operate the aircraft safely and efficiently. For instance, knowing the Vref or landing reference speed ensures that the approach is stable and appropriate for landing. Consequently, these reference speeds form a vital part of every pilot's flight operations manual, ensuring compliance with performance thresholds throughout all flight conditions.

The other options, while they each relate to aviation, do not correctly define V-speeds. Variations of engine speeds, for example, relate more to tachometers and engine management rather than reference speeds for flight performance. Vario types for GPS navigation does not accurately address the concept of V-speeds, as it pertains more to altitude variation indicators or devices. Visual aids for instrument flight might refer to visual approach slope indicators or other navigational aids, which similarly do not capture the essence of V-speeds.