At what rate does the approach surface extend upwards for a visual approach?

At what rate does the approach surface extend upwards for a visual approach?

• A. 20:1
• B. 50:1
• C. 34:1
• D. 7:1

Answer: (A)

The main idea is the slope of the imaginary approach surface used for a visual approach. This surface rises as you move away from the runway along the extended centerline, and for a visual approach that slope is defined as a horizontal-to-vertical ratio of 20 to 1. In other words, for every 20 units of horizontal distance, the surface height increases by 1 unit. That yields a gentle upgrade of about 2.9 degrees, roughly matching what you’d expect when guiding a visual approach. To see it in numbers: at 2,000 feet out, the surface would rise about 100 feet (2,000 ÷ 20). At 4 NM (about 24,000 feet), it would rise around 1,200 feet. This rate provides the needed obstacle clearance without making the surface too steep. Other options don’t reflect this standard slope. They would produce slopes that are either too steep or too shallow for the visual-approach surface defined in regulatory practice.

The main idea is the slope of the imaginary approach surface used for a visual approach. This surface rises as you move away from the runway along the extended centerline, and for a visual approach that slope is defined as a horizontal-to-vertical ratio of 20 to 1. In other words, for every 20 units of horizontal distance, the surface height increases by 1 unit. That yields a gentle upgrade of about 2.9 degrees, roughly matching what you’d expect when guiding a visual approach.

To see it in numbers: at 2,000 feet out, the surface would rise about 100 feet (2,000 ÷ 20). At 4 NM (about 24,000 feet), it would rise around 1,200 feet. This rate provides the needed obstacle clearance without making the surface too steep.

Other options don’t reflect this standard slope. They would produce slopes that are either too steep or too shallow for the visual-approach surface defined in regulatory practice.