PPRuNe Forums - View Single Post - What's a 12% glideslope? (asks a mentally retarded ATPL student)
Old 4th August 2002 | 18:07
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Babi Melayu
 
Joined: Feb 2001
Posts: 13
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From: Malaysia
Please don't call yourself a retard.


You might be familiar with the more common 3-degree glideslope or gradient of 5%. The 5% means 5 / 100, 5 feet lost vertically (y-axis) for every 100 feet travelled horizontally (x-axis). When you intend to find the angle subtended by this 5 (y-axis) and 100 (x-axis), you just take the inverse tangent of them both - opposite over adjacent i.e. inverse tangent of 5 / 100. The result is an angle of 2.83 degrees ( which is close to the 3-degree we mentioned).


The TWELVE percent (12%) slope means you lose 12 feet vertically for every 100 feet travelled horizontally and this is simply a much steeper slope i.e. a whopping 6.84 degrees glideslope! ( Inverse tangent of 12 over 100 gives us 6.84)


Who uses the 12% slope, by the way?

Last edited by Babi Melayu; 4th August 2002 at 18:14.
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