Accession Number : AD0259120

Title :   PERCENTILES OF AIR DENSITY AT STATION LEVEL

Corporate Author : AIR WEATHER SERVICE SCOTT AFB ILL

Personal Author(s) : KOCHANSKI,ADAM

Report Date : MAY 1961

Pagination or Media Count : 45

Abstract : A method is given for estimating certain percentiles of density at station level for any discrete point over the Northern Hemisphere. The main operational problem that requires knowledge of density distributions concerns SAC bombers that are on 15-minute alert. Occurrences of runway-density lower than a certain critical value may prevent the take-off of heavily-loaded aircraft. The hovering of the helicopters may be impeded by low densities. A technique is described which reconstructs that part of the cumulative frequency curve of density which lies between the 5th and the 95th percentile. The technique permits one to estimate six points of the curve. The accuracy of estimates varies. The method was devised to give very high accuracy for the 5th, 10th, and 20th percentiles, i.e., for low densities that are adverse to aircraft take-off. For higher-than-average densities (i.e., for the 80th, 90th, and 95th percentiles) the technique allows only for rough estimates. (Author)

Descriptors :   *AIRCRAFT, *ATMOSPHERES, DENSITY, DETERMINATION, GEOGRAPHY, LANDING, STATISTICAL ANALYSIS, SURFACE PROPERTIES, TAKEOFF, TEST METHODS

Distribution Statement : APPROVED FOR PUBLIC RELEASE