14 CFR §93.162

The Pearson Field Airport Special Flight Rules Area is designated as that airspace extending upward from the surface to but not including 1,100 feet MSL in an area bounded by a line beginning at the point where the 019° bearing from Pearson Field intersects the 5-mile arc from Portland International Airport extending southeast to a point 1 1/2 miles east of Pearson Field on the extended centerline of Runway 8/26, thence south to the north shore of the Columbia River, thence west via the north shore of the Columbia River to the 5-mile arc from Portland International Airport, thence clockwise via the 5-mile arc to point of beginning.