Head impact area
Head impact area means all nonglazed surfaces of the interior of a vehicle that are statically contactable by a 6.5-inch diameter spherical head form of a measuring device having a pivot point to top-of-head dimension infinitely adjustable from 29 to 33 inches in accordance with the following procedure, or its graphic equivalent:
(a) At each designated seating position, place the pivot point of the measuring device—
(1) For seats that are adjustable fore and aft, at—
(i) The seating reference point; and
(ii) A point 5 inches horizontally forward of the seating reference point and vertically above the seating reference point an amount equal to the rise which results from a 5–inch forward adjustment of the seat or 0.75 inch; and
(2) For seats that are not adjustable fore and aft, at the seating reference point.
(b) With the pivot point to “top-of-head” dimension at each value allowed by the device and the interior dimensions of the vehicle, determine all contact points above the lower windshield glass line and forward of the seating reference point.
(c) With the head form at each contact point, and with the device in a vertical position if no contact points exists for a particular adjusted length, pivot the measuring device forward and downward through all arcs in vertical planes to 90° each side of the vertical longitudinal plane through the seating reference point, until the head form contacts an interior surface or until it is tangent to a horizontal plane 1 inch above the seating reference point, whichever occurs first.