How is the miles needed to descend calculated when approaching from 35,000 feet?

The calculation for descending from 35,000 feet to a lower altitude effectively utilizes the general rule of thumb for descent rates in aviation. The correct approach lays out the principle of descent in which, for every 1,000 feet of altitude, a pilot typically needs approximately 3 miles to achieve a safe and smooth descent under standard conditions.

In this context, when approaching from 35,000 feet, the correct calculation suggests multiplying the number of feet needing to be descended (which is 35,000 feet) by 3. This means the total descent distance would approximate to 105 miles. This distance ensures that the aircraft can descend at a safe and controlled rate, which is crucial for aviation safety and operational planning during an approach.

The other options do not effectively provide the correct method for calculating the miles needed for descent based on standard aviation practices. They might mislead a pilot in approach planning, and therefore, option B stands out as the correct and most practical choice.