When Is The Best Time To Start Descending

Here are two options to consider.

DISTANCE

When cruising at 10,000 feet. (10,000/1,000) x5 = 50 miles out and this allows for most piston airplanes to maintain 500 ft/min all the way down to desired altitude.

Commercial and Jet aircraft use a multiplier of 3 and 2000 ft/min.

Mango 737 -800 (Pic- Julian Smith)

Many pilots use what they call the 3-to-1 rule (three miles distance per thousand feet in altitude.) This is a good rule for determining when to start your descent.

Take your altitude in feet, drop the last three zeros, and multiply by 3. So if you are at 12000 ft. agl, means 12 multiply by 3 equals 36 miles out to start your descent. You can check your DME from airport if it you have one.

TIME

Another good rule of thumb is to allow yourself two minutes for each 1,000 feet of altitude you need to lose. So, if you’re cruising at 10,000 feet above field elevation, start descending 20 minutes before your planned arrival.

Madiba Bay School of Flight Sling 2 (Pic-Julian Smith)

So whether you use time or distance, is up to you on how comfortable you feel.

SAAF DC-3 landing in Port Elizabeth (Pic- Julian Smith)

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