In order to safely land, the angle that a plane approaches the runway should be no more than 15°. A plane is approaching Ottawa
Macdonald–Cartier International Airport to land. It is at an altitude of 500 m and a horizontal distance of 3 km from the start of the runway. At what angle is the plane approaching and is it safe for the plane to land?
The distance opposite the angle of elevation is the plane's height, 500 m. The distance adjacent to the angle of elevation is the horizontal distance to the plane, 3 km = 3000 m. Then the angle is found from ...
tan(α) = 500/3000 = 1/6
α = arctan(1/6) ≈ 9.46°
The plane is approaching at an angle of 9.46°. It is safe to land, since that angle is less than 15°.
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<em>Additional comment</em>
The usual descent angle for most commercial air traffic is 3°. Some airport geography demands it be different (steeper). A higher descent angle can put undue stress on the landing gear.
