Prevailing visibility
Prevailing visibility in
In Canada, it is the maximum visibility value common to sectors comprising one-half or more of the horizon circle.[1] The horizon circle may be divided into as many sections as required based on differing visibilities.
When the prevailing visibility is less than 4 miles, or goes from less than 4 miles to four miles or greater, tower personnel are required to take a prevailing visibility reading. If this reading differs from the ground reading (i.e., different readings for different heights), the lower value of the two is used for aircraft operations. Also visibility is defined as greatest distance at which an object of specified characteristics can be seen and identified by an observer with normal flight under normal condition in daylight.[2]
References
- ^ Canada, Environment and Climate Change. "MANOBS Manual of Surface Weather Observations: visibility - Canada.ca". www.ec.gc.ca. Retrieved November 14, 2017.
- ^ "Chapter 2 Section 6 Weather Information". Archived from the original on 2005-11-26. Retrieved 2006-01-19.
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