In a glide with an angle of attack of 10 degrees, how much altitude is lost in 1 mile?

• A. 240 ft
• B. 480 ft
• C. 960 ft
• D. 120 ft

Answer: (B)

In a glide, how much altitude you lose over a given horizontal distance depends on the glide angle—the path’s slope below the horizon. The vertical drop equals the horizontal distance times the tangent of the glide angle. The angle of attack tells you about lift and drag, but it isn’t the same as the glide angle; a steady glide typically sits at a small glide angle, often around 5 degrees for many light aircraft.

If the glide angle is about 5 degrees, tan(5°) ≈ 0.0875. For 1 mile (5280 ft) of horizontal distance, the altitude lost is 5280 × 0.0875 ≈ 462 ft, which is in the neighborhood of 480 ft. So the expected loss is around 480 ft per mile. The 10-degree angle of attack describes lift characteristics, not the actual descent angle in a steady glide, which is why the 480 ft figure is the reasonable estimate.