What is the formula for descent in aviation?

In aviation, pilots adopted a formula to assure a slow, based on a 3? descent rate, steady and comfortable descent: the rule of three or "3:1 rule of descent". This rule implies 3 NM of travel should be allowed for every 1,000 feet (300 m) of descent.



The most common "rule of thumb" formula for descent used by pilots is the 3:1 Rule of Descent. To calculate the distance needed to begin a descent, you take the altitude you need to lose (in thousands of feet) and multiply it by three. For example, if a plane is at 30,000 feet and needs to descend to sea level, the pilot should start the descent roughly 90 nautical miles from the destination (30×3=90). To determine the required rate of descent (vertical speed), a common formula is to multiply the aircraft's groundspeed by five. If a jet is traveling at 400 knots, a descent rate of 2,000 feet per minute (400×5=2000) would maintain a standard 3-degree glide path. In 2026, while flight management computers (FMC) calculate these "Top of Descent" points with extreme precision using real-time wind data and aircraft weight, these mental formulas remain essential "sanity checks" for pilots to ensure they don't arrive "too high or too fast" for a safe landing.

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In aviation, the rule of three or 3:1 rule of descent is a rule of thumb that 3 nautical miles (5.6 km) of travel should be allowed for every 1,000 feet (300 m) of descent.

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A commercial aircraft will typically descend at between 1,500 and 3,000 feet per minute. The Space Shuttle, the most inefficient glider of its time, used a far larger descent angle, descending at 10,000 feet per minute (enough to make you pay attention to the fasten seatbelt sign).

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That's why pilots are taught the 1 in 60 rule, which states that after 60 miles, a one-degree error in heading will result in straying off course by one mile. Which means the lake you planned to fly over could turn out to be a mountain.

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In a plane, cruising at a steady speed and steady altitude, there are two ways to come down: You can simply point it down, in which case it will speed up, just like a car going down a hill. Or, you can reduce the power. If you keep the plane at a steady speed, it will start to descend.

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The A320 will descend around 2500-3000 fpm in open descent mode. You can control this by changing the airspeed you are descending at. Faster airspeed will increase descent rate and slower will decrease it, in open descent mode.

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As part of the testing of a new aircraft, the manufacturer must demonstrate that all passengers can be evacuated in a short amount of time when an emergency arises - within 90 seconds to be precise. If it doesn't comply, the aviation authorities won't approve its safety certification.

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Top Of Climb (TOC). An identifiable waypoint representing the point at which cruise altitude is first reached. TOC is calculated based on your current aircraft altitude, climb speed, and cruise altitude.

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