What is the formula for 3 degree descent?

Formula for 3-Degree Descent

Maintaining a constant 3-degree glide path during an aircraft's descent requires a calculated rate of descent. A simple formula is used to determine the required rate of descent based on the aircraft's ground speed.

Formula:

Rate of Descent (ft/min) = Ground Speed (knots) x 5

Explanation:

• The rate of descent in feet per minute (fpm) is directly proportional to the aircraft's ground speed in knots.
• The constant factor of 5 represents the vertical descent per unit of horizontal distance traveled when maintaining a 3-degree glide path.

Example:

If an aircraft is flying at a ground speed of 120 knots, the required rate of descent to maintain a 3-degree glide path can be calculated as follows:

Rate of Descent = 120 knots x 5
Rate of Descent = 600 feet per minute

Therefore, the aircraft should descend at a rate of 600 feet per minute to maintain a constant 3-degree glide path.

Note:

It is important to consider the aircraft's weight, configuration, and wind conditions when determining the actual rate of descent. The formula provided is a general guideline and may need to be adjusted accordingly.