Question

Assuming a 3 degree glide slope, what are the horizontal distances to the runway threshold when the aircraft is at: (a) 200 foot decision height (DH) (e.g., CAT I); and (b) 100 foot decision height (CAT II)?

Answer 1

The horizontal distances to the runway threshold can be calculated using trigonometry. When the aircraft is at a 200-foot decision height, the distance is 6691.16 feet. At a 100-foot decision height, the distance is 3345.58 feet.

Step-by-step explanation:

To calculate the horizontal distances to the runway threshold, we can use the concept of trigonometry. The glide slope is the ratio of the vertical descent to the horizontal distance. In this case, the glide slope is 3 degrees, which is equivalent to a ratio of 1:20.

(a) When the aircraft is at a 200-foot decision height (DH), we can use the trigonometric function tangent to find the horizontal distance. Tan(3 degrees) = height / horizontal distance. Rearranging the equation, we get horizontal distance = height / tan(3 degrees). Plugging in the values, we get horizontal distance = 200 / tan(3 degrees) = 6691.16 feet.

(b) For a 100-foot decision height (DH) at CAT II, the calculation is the same. Plugging in the values, we get horizontal distance = 100 / tan(3 degrees) = 3345.58 feet.