P ; ¥S_AND 1. Conelusions a. General: (1) The significant fall-out ares from large yield shots was a sone on the order of 100 miles wide and 300 miles long, Because of varia=~ tions in the wind forecasts, diffusion of the atomic aloud along its pzth of f-ll-cut and changes in direction of drift of the cloud as it moves outside the influence of ground sero winds, & meh larger exclusion area had to be sonsidered associated with the forecast fall-out sone. (2) The employment of large numbers of search aircraft to sweep vast forecast fall-out areas was an expensive cperation. Successive daily repetition of the sweeps was often necessary due to shct delays arising from unfavorable winds and the difficulty in making accurate long-range weather forecasts. . (3) Although the sise cf the area set up prior to the operaticn for diversion of transient shipping was adequate, is did act extend to all natimalities, (4) The adoption, after the first shot, of a large Danger srea for the remaining period of the CASTLE Operation was the logical sclution to the transiem shipping problem for two major reasons: (a) The Danger irea applied to all nationalities. ‘(o) Due to advance clearanse of the entire Danger area, serial sweeps of the mijcr portion of this area were basically in the cate= gory of checking compliance with the Danger irea notice rather than attempts t2 eomtact and effect time-consuming diversion of shipping. .s 4 consequence, the sweeps were mie later in the pre-shot preparations ani with loss chance of repeats arising from shot delays ius to weather, 87 |