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The outer surface, shown on Red Lake Airport Zoning Plan No. 60-041 86-112, Sheets 1 to 9 inclusive, dated September 28, 1988, is an imaginary plane established at a constant elevation of 45 m above the elevation of the airport reference point, except that, where that plane is less than 9 m above the surface of the ground, the outer surface is located at 9 m above the surface of the ground.
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