It is better to take off into the wind. The lifting power increases with the velocity of the plane relative to the surrounding air. When the plane takes off with the wind following, the plane's velocity relative to the air is equal to its velocity relative to the ground, less the velocity of the wind; but when it takes off into the wind, the plane's velocity equals the sum of these two velocities. Thus a plane taking off into the wind reaches the same air speed at a lower ground-speed than if it were to take off in a tail wind. Therefore the lifting power reaches the necessary level and the plane leaves the ground at a lower ground speed-which is more advantageous in many respects, and less dangerous.