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Proper descent rate

When arriving at your destination via a STAR, you are required to be at a certain altitude when at a certain position. There is a simple way to calculate how many miles you need to loose the necessary altitude and cross the fix as instructed.

Ok, say you are cruising at FL350 - 35 thousand feet. You are instructed to cross a certain fix at 100 - 10 thousand feet. Lets figure out how many miles you need to accomplish this:

Step 1 - Subtract the altitude you need to be at over the fix from your cruise level: 35000-10000 = 25000
Step 2 - Drop all zeros from your answer in step one = 25
Step 3 - Times your answer from step 2 by 3: 25 x 3 = 75

You need to start your descent 75 NM from the fix you are required to cross at 10000. I like to add 5 more NM to this figure for a little buffer zone. (80NM)

Now, we are not done. How fast should you descend?

Depending on aircraft you are going to want to reduce your IAS, indicated airspeed to fit your own needs. To use the "3 times rule" above, you will need to descend as follows in the chart below. You can find your ground speed on your GPS. Again, you will need to reduce your IAS! As you can see, the faster you are going, the steeper the vertical speed will have to be. If you increase your V-speed, without reducing engine power and IAS, you will only speed up! Click here to download the chart below in word format for printing and quick reference.

Example: If your ground speed is 380, you must descend at a rate of 1900 feet per minute