How is the rate of descent calculated?

The rate of descent is commonly calculated using a formula that relates the ground speed of the aircraft to the desired descent rate in feet per minute (FPM). In this case, the accurate formula is FPM = GS x 5, where GS is the ground speed in knots. This indicates that for every knot of ground speed, you should descend at a rate of approximately five feet per minute.

This calculation is useful for ensuring a controlled and timely descent, especially when preparing for an approach or landing. It allows pilots to estimate how long it will take to reach a desired altitude based on their current speed. This ratio helps maintain a safe and manageable descent profile, which is essential for effective flight operations.

Understanding this formula is particularly important for instrument flight, where maintaining altitude and managing descents requires precise calculations to ensure safety and compliance with air traffic control instructions.