Which surface begins at the horizontal surface?

Which surface begins at the horizontal surface?

• A. The conical surface
• B. The primary surface
• C. The transitional surface
• D. The approach surface

Answer: (A)

The surface that begins at the horizontal surface is the conical surface. In the set of imaginary airport surfaces, the horizontal surface creates a horizontal plane around the runway. The conical surface starts where that horizontal plane ends—at the outer boundary of the horizontal surface—and then extends outward and upward in a cone shape. This starting point at the edge of the horizontal surface is why the conical surface is described as beginning there. The other surfaces have different starting points: the primary surface runs along the runway centerline, transitional surfaces begin at the edges of the primary surface, and the approach surface starts at the end of the runway along the approach path.

The surface that begins at the horizontal surface is the conical surface. In the set of imaginary airport surfaces, the horizontal surface creates a horizontal plane around the runway. The conical surface starts where that horizontal plane ends—at the outer boundary of the horizontal surface—and then extends outward and upward in a cone shape. This starting point at the edge of the horizontal surface is why the conical surface is described as beginning there. The other surfaces have different starting points: the primary surface runs along the runway centerline, transitional surfaces begin at the edges of the primary surface, and the approach surface starts at the end of the runway along the approach path.