Slant and runway visual range relationships

Download or read book Slant and runway visual range relationships written by William Lewis and published by . This book was released on 1977 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was conducted to determine if any significant relationships existed between horizontal and slant visibility during fog conditions. Approximately 11,000 sets of atmospheric transmittance observations in fog were obtained at six horizontal levels from 5 to 155 feet and from the 5- to 155-foot slant path by extinction-type transmissometers mounted on two airfield towers separated by 250 feet. Each observation set was classified into one of seven vertical profile classes according to the transmittance difference between the top (155-foot) and bottom (5-foot) transmissometers. The implications of the various fog structures for aircraft landings are discussed. Average 5- to 155-foot slant visual range versus 5-foot runway visual range (SVR-RVR) ratios and standard deviations of ratios were computed by profile class. An analysis showed that results are definitive and could form the basis of a procedure for estimating SVR from RVR through fog profile measurement. A multiple linear regression analysis to predict SVR from RVR, surface temperature, windspeed, and atmospheric stability showed RVR to be the best predictor of SVR, while the other variables showed some effect only with dense fog. These results are considered tentative, since they are based on a limited data sample. Fifteen-minute changes in SVR by profile class were examined for certain SVR ranges. Results showed that knowledge of the profile class would not significantly improve 15-minute persistence forecasts of SVR. (Author).