Comparison of Slant and Runway Visual Range Relationships for 100, 124, and 155 Feet

Ratios of slant visual range measured from heights of 100, 124, and 155 feet to horizontal visual range measured at 15 feet were computed for low- visibility regimes. These ratios were found to be related to the linear fog density profile expressed as the difference in horizontal atmospheric transmittance between the top 100-, 124-, and 155-foot and bottom 15-foot levels. It was determined that useful estimates of slant visual range could be provided through these relationships. The predictions would be most accurate when the visibility decreased with height most common fog structure. A slight increase in accuracy would also be expected with decreasing slant height.