Instrument Rating Checkride Practice Test

How do you calculate how far out to begin your descent using the 3-1 Rule?

1. Multiply feet to lose by 5

2. Multiply feet to lose by 2

3. Multiply feet to lose by 3

4. Use constant descent rates

The correct answer is: Multiply feet to lose by 3

The 3-1 Rule is a useful guideline for determining the distance required to begin a descent when you're approaching a destination. According to this rule, for every 1,000 feet of altitude you need to lose, you should begin your descent approximately 3 miles out. This means if you are at an altitude of, for example, 12,000 feet and need to descend to sea level, you would lose 12,000 feet, which translates to needing to start your descent about 36 miles away from your destination (12 x 3 = 36). This rule helps pilots calculate when to initiate a descent to allow for a stable and gradual approach, making it easier to manage airspeed and configure the aircraft appropriately for landing. While other options provide different multiplication factors, they do not align with the established 3-1 Rule used for descent planning in aviation. Therefore, using a factor of 3 per 1,000 feet lost provides the correct calculation for anticipating your descent distance.