Where does the Transitional Surface commence, and what is its slope?

Where does the Transitional Surface commence, and what is its slope?

• A. Commences at the edges of the primary surface, perpendicular to the runway centerline and transitions to the horizontal surface. Slope 7:1.
• B. Begins at the runway threshold and transitions to the horizontal surface. Slope 3:1.
• C. Starts at the end of the approach surface and extends outward. Slope 20:1.
• D. Begins at the runway centerline and extends vertically with slope 50:1.

Answer: (A)

Transitional surfaces are the outward, upward connections from the runway’s primary surface to the surrounding horizontal plane, designed to keep obstacles clear as you move away from the runway. They start at the outer edge of the primary surface and rise away from the runway at a constant slope, perpendicular to the runway centerline, until they meet the horizontal plane. That fixed slope is 7 horizontal units for every 1 vertical unit (7:1). So the correct description is that the transitional surface begins at the edges of the primary surface and transitions to the horizontal surface with a 7:1 slope. The other options place the start point in the wrong location (threshold, end of the approach surface, or centerline) or specify an incorrect slope, which doesn’t match how transitional surfaces are defined.

Transitional surfaces are the outward, upward connections from the runway’s primary surface to the surrounding horizontal plane, designed to keep obstacles clear as you move away from the runway. They start at the outer edge of the primary surface and rise away from the runway at a constant slope, perpendicular to the runway centerline, until they meet the horizontal plane. That fixed slope is 7 horizontal units for every 1 vertical unit (7:1).

So the correct description is that the transitional surface begins at the edges of the primary surface and transitions to the horizontal surface with a 7:1 slope. The other options place the start point in the wrong location (threshold, end of the approach surface, or centerline) or specify an incorrect slope, which doesn’t match how transitional surfaces are defined.