generally scutherly winds at those levels which hed az average yolocity of twelve knotse Subsequent movomont was to tho cast. and is reflocted by the air particla trajectorics. This force of the KOOM day cloud trackersw It cas waw vorified by wae undoubtedly this sagmont of the cloud that caused the fall= ‘“hu§.Sbaorved orRongorik and Rongclap Atolls following KOON. Unfogtunately thore is no data svailable on tho tim of fallout at either of these atolls. On tho basis of tho cloud tracking data it; would appoar that this fallout should have commenced aboutycight hours after the shot. Tho highest lovels of the cloud (twebtty-five thousand to tho top of the mishroam at about fifty thousend feet) initially moved to the east~northoaat at about twenty-five kmots. This movement continued in the sane general direction outside the PPG. Other than the fallout on Rongerik and Rongelap, which has beenpreviously mentioned, no other atolis wero mterially affected by debris from the KOON clouds 3 SAMPLING ALiCRAFT REPORTS: Aa in the case of previous shots, these reports were recorded by RadSafe personnel aboard the command ship from plus two to plus seven hours. Reports from these aircraft provided the first data available on the maximum cloud height and initial cloud movement... The sampling activities of the planes confirmed the accuracy of the forecast air radex (see App II). As would be expected, the radia~. tion exposure of the aircraft crews wae relatively low. be SWECT-SOUR_ REPORTS: These reports were submitted by any aircraft encountering radio=active. contamination and not reporting by other means. No such ree porta were received following KOON. Se SPECIAL CLOUD TRACKING (\ILSON) FLIGHTS: a. The initial phases of the KOON cloud tracking effort dupe licated those which were so successfully axployed for ROMEO, Two \WB=29's, WILSON T.0 and WILSON THREE, were placed in a holding pattern fifty miles west of Ground Zcro at plus two hours, As will be seen from App. I, the location and orientation of this pattern is such that any cloud segments moving toward sither Eniwetok or Ujo= lange should be intercepted by at least one of these aircraft. WILSON THREE, which flew at 4900 feet in the pattern, should have encountered any matcrial, being carried by the winds below the first shear level. WILSON , flying at 10,000 feet, would be expected to vorify any westerly movoment of the middle cloud. &, Tho .ILSON THREE aircraft made the only contamination con- tact in tho racc-track pattorn at 2335 Zebra (plus 5:15 hours) fifty milos west of Ground Zero. This contamisation (15 Mr/Hr) could have had two possible sources. Tho first source being that of vory light particlos from the lowest level of the cloud. Ma26 doth tho air radex