Fall line (skiing)
In alpine skiing, a fall line refers to the line down a mountain or hill which is most directly downhill. That is, the direction a ball would roll if it were free to move on the slope under gravity. A skier is said to be "skiing the fall line" if he is skiing a line with his skis pointing generally down, rather than traversing across it.
Mathematically the fall line, the line of greatest slope, is the negative of the gradient (which points uphill) and perpendicular to the contour lines.
Fall-Line Analysis: An evaluation of the mountain terrain in terms of the natural fall-line. The fall-line is the path an object takes as it moves down a slope perpendicular to the contour lines. Fall-line skiing provides for the natural flow of skier routes which will serve all skier ability levels, from the top of the mountain to the base areas, on a consistent basis. Consistency of fall-line provides the best recreational skiing experience with the least amount of environmental disruption due to minimal requirements for earthwork during ski trail construction.