What type of wind helps an airplane increase its ground speed by blowing in the same direction it is traveling?

A tail wind is defined as a wind that blows in the same direction as the movement of an aircraft. This type of wind can significantly enhance the ground speed of the airplane, allowing it to travel faster over the ground than it would without wind assistance. When a tail wind is present, it adds to the forward motion generated by the aircraft's engines, making takeoffs and landings more efficient by reducing the distance required for these maneuvers and enabling quicker overall travel times.

In contrast, a head wind would oppose the airplane's direction of travel by blowing against it, which would decrease ground speed. A cross wind blows perpendicular to the direction of travel, affecting the aircraft's stability and requiring the pilot to adjust their flight path to maintain control. Lastly, a flank wind is not a commonly used term in aviation and is less relevant to the dynamics of flight compared to the other types of wind.