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<br /> a Wind coverage is that percent of time for which operations are con- -
<br /> sidered Safe due to acceptable crosswind components. The desirable
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<br /> wind coverage for an airport is 95 percent,based on the total hours
<br /> of weather observations. At some locations, the daily time period 7,
<br /> for weather observations is less than 24 hours; i.e. , 16 hours.
<br /> In any event, the data collected must be applied with an under-
<br /> standingiof the objective; i.e. , to attain 95-pereent usability./At
<br /> • :.., many airPorts, airplane operations are almost nil after-dark.
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<br /> Accordingly, it may be desirable to analyze the wind data on less ....
<br /> - ..... than a 24-hour observation period. Also, at resort airports, where
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<br /> ',. operations are predominantly seasonal, regard should be given to
<br /> , -. the wind data for the predominant-use period.
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<br /> . , b. Where a single runway cannot be oriented to provide 95-percent
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<br /> . 1 coverage,, one or more additional runways will be required to raise
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<br /> the coverage to that value.
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<br /> c The acceptable coverage value of 95 percent was selected after con-
<br /> • ..• sideratio'n of various factors influencing operations to and from _
<br /> airports and the economics of providing the coverage. In any air-
<br /> ., port operiation, there are periods when factors other than wind
<br /> determine j when a runway may be used. Low ceilings, reduced
<br /> visibility, periods of runway maintenance, etc. , may preclude use
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<br /> of a particular runway even though existing wind conditions are
<br /> favorable.
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<br /> 1. Appendix 3, Weather Data SoUroe'-and Analysis, states in det41 how
<br /> a standar1i wind rose is compiled and used.
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<br /> Chap 3
<br /> Page 8
<br /> Par 10
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