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AFMAN15-111 12 MARCH 2019 41
8.5.2.2. If a marker can be seen, the visibility is about the same as the distance to the
marker.
8.5.2.3. If a marker cannot be seen due to weather and/or reportable obscurations, the
visibility is less than the marker.
8.5.3. Under uniform conditions, consider the prevailing visibility to be the same as that
determined in any direction around the horizon circle.
8.5.4. Under non-uniform conditions, divide the horizon into sectors that have uniform
visibility and represent at least 1/8th of the horizon circle.
8.5.4.1. The greatest distance seen in least half of sectors that make up the horizon circle
(may be non-contiguous) is reported as the prevailing visibility.
8.5.4.2. The visibility in sectors is reported in remarks when they differ from the prevailing
visibility by one or more reportable value and either the prevailing or the sector visibility
is less than 3SM (4800 m) or if it is considered operationally significant; see examples in
Figure 8.1 and Attachment 3 for format.
8.5.5. If the visibility is rapidly fluctuating by at least 1/2SM (0800m) during the period of the
observation and the prevailing visibility is less than 3SM (4800 m), the visibility is considered
variable and the minimum and maximum visibility values observed are reported in remarks;
see Attachment 3 for format.
Figure 8.1. Determining Prevailing and Sector Visibility.
