Comments on: Aviation Rules of Thumb http://flypatchfly.com/aviation-rules-of-thumb/ Making the most of your private pilots license. Sat, 06 Nov 2010 15:08:14 +0000 hourly 1 http://wordpress.org/?v=3.0.1 By: Peter http://flypatchfly.com/aviation-rules-of-thumb/comment-page-1/#comment-6880 Peter Thu, 10 Dec 2009 14:33:16 +0000 http://www.flypatchfly.com/?p=113#comment-6880 What is wrong with this rule of thumb: How far out should you start your decent to the field? Multiply your altitude (divided by 1000) times 3 and add 10. For example, if you’re flying at 7000 agl, you would multiply 7 x 3 = 21 + 10 = 31 nm out. Calculation 1: So, when at 1000ft I had to start at 1000/1000 = 1* 3 = 3 + 10 = 13 nm out to descent. Calculation 2: Flying at 80 kts I have a 400ft per minute descent rate. How about that? Loose 1000 ft in 13 nm??? I fly with 80kts = 1,33nm per minute. With 400 ft/miute I do the descent in 2,5 minutes. And with 1,33nm per minute the distance= 2,5 x 1,33 = 3,325nm. CONCLUSION: The rule of thumb is not correct. It must be: ((Altitude - Pattern Altitude)/1000) * 3 What is wrong with this rule of thumb:
How far out should you start your decent to the field?
Multiply your altitude (divided by 1000) times 3 and add 10.
For example, if you’re flying at 7000 agl, you would multiply 7 x 3 = 21 + 10 = 31 nm out.

Calculation 1: So, when at 1000ft I had to start at 1000/1000 = 1* 3 = 3 + 10 = 13 nm out to descent.
Calculation 2: Flying at 80 kts I have a 400ft per minute descent rate.

How about that? Loose 1000 ft in 13 nm???
I fly with 80kts = 1,33nm per minute.
With 400 ft/miute I do the descent in 2,5 minutes. And with 1,33nm per minute the distance= 2,5 x 1,33 = 3,325nm.

CONCLUSION:
The rule of thumb is not correct. It must be: ((Altitude – Pattern Altitude)/1000) * 3

]]> By: PlasticPilot http://flypatchfly.com/aviation-rules-of-thumb/comment-page-1/#comment-1167 PlasticPilot Mon, 03 Nov 2008 18:11:37 +0000 http://www.flypatchfly.com/?p=113#comment-1167 Great post. I like simple rules, and simple addition to check-lists, like the good old "red-blue-green" on short final. Great post. I like simple rules, and simple addition to check-lists, like the good old “red-blue-green” on short final.

]]>