[...]
The outer surface, shown on Churchill Airport Zoning Plan No. E2244 dated October 23, 1986, is an imaginary surface located at a common plane established at a constant elevation of 45 m above the elevation of the airport reference point, except that, where that common plane is less than 9 m above the surface of the ground, the outer surface is an imaginary surface located at 9 m above the surface of the ground.
[...]