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Where are VASIs located on a field ?

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epsa...@gmail.com

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Dec 25, 2012, 6:26:47 PM12/25/12
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Where are VASIs located on a field that doesn't have an ILS ? Is it a certain number of feet from end of runway ? Does it depend on runway length ? If you want to land on a short runway when is it safe to dip below VASI ? Must there be a certain number of hundreds of feet from the threshold clear of obstructions ? Clearly you don't want to cross the threshold at 50 feet if you are flying , e.g. a Mooney onto a 2300 foot field, you'll waste the first 1000 feet...

Sam Spade

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Jan 12, 2013, 4:33:55 PM1/12/13
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On 12/25/2012 3:26 PM, epsa...@gmail.com wrote:
> Where are VASIs located on a field that doesn't have an ILS ? Is it a certain number of feet from end of runway ? Does it depend on runway length ? If you want to land on a short runway when is it safe to dip below VASI ? Must there be a certain number of hundreds of feet from the threshold clear of obstructions ? Clearly you don't want to cross the threshold at 50 feet if you are flying , e.g. a Mooney onto a 2300 foot field, you'll waste the first 1000 feet...
>

Do the math using the TCH and the angle.

brian whatcott

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Jan 12, 2013, 9:02:02 PM1/12/13
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Here we go then: X / TCH = arc cot (glide slope angle)
X = TCH*arc cot(glide slope angle) = 50 * arc cot(3deg)
X = 50 * Arc cot (3 deg) = 922ft

He said 1000 ft. You were making which point again?

:-)

Brian W
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