(b) a surface abutting the end of the strip associated with runway approach 25 consisting of an inclined plane having a ratio of one (1) foot measured vertically to fifty (50) feet measured horizontally rising to an imaginary horizontal line drawn at right angles to the projected centre line of the strip, one thousand (1,000) feet measured vertically above the elevation at the end of the strip and fifty thousand (50,000) feet measured horizontally from the end of the strip, the outer ends of the imaginary horizontal line being eight thousand (8,000) feet from the projected centre line, excepting thereout all that portion of the said surface contained within the vertical projections of the boundaries of the Clearwater Indian Reserve No. 175,
