MaxSez: Here’s “When” you Should Start Your Descent for Arrival at your Terminal Destination. A simple “Rule of Thumb”;
So, 3 degrees is a comfortable descent rate in just about any aircraft. But when you’re approaching an airport, how do you know when to start down?
Divide the altitude you need to lose by 300 .
For example, if you’re at 11,000’, and you need to get down to a pattern altitude of 2,000’, you need to descend 9,000’.
9,000/300 = 30 miles.
If you start a 3-degree descent 30 miles out (ATIS Range) you’ll hit pattern altitude as you reach the airport. Keep in mind, you’ll want to add a few miles on to your number, so you hit pattern altitude slightly before you get to the airport.
(Pattern Altitude: Turbine/1500ftAGL… Aspirator 1000ftAGL)