Which surface begins at the runway and extends upwards/outwards at a rate of 7:1?

Which surface begins at the runway and extends upwards/outwards at a rate of 7:1?

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

Answer: (C)

In airport design, there are several imaginary surfaces that protect airspace around a runway. The one that starts at the runway and rises as it extends outward with a constant vertical-to-horizontal ratio of 7 to 1 is the transitional surface. This surface runs from the sides of the primary runway and climbs upward at 7 feet for every 1 foot of horizontal distance until it meets the conical surface. That 7:1 slope is the defining feature of the transitional surface, setting it apart from the approach surface (which follows the approach path), the conical surface (which extends outward to meet the transitional surface), and the horizontal surface (a flat plane at the airport’s elevation).

In airport design, there are several imaginary surfaces that protect airspace around a runway. The one that starts at the runway and rises as it extends outward with a constant vertical-to-horizontal ratio of 7 to 1 is the transitional surface. This surface runs from the sides of the primary runway and climbs upward at 7 feet for every 1 foot of horizontal distance until it meets the conical surface. That 7:1 slope is the defining feature of the transitional surface, setting it apart from the approach surface (which follows the approach path), the conical surface (which extends outward to meet the transitional surface), and the horizontal surface (a flat plane at the airport’s elevation).