Ivy with success, ita serious limitations were not apparent until the BRAVO shot. Oxi Operation IVY the fortunate circumstance of the absence cf any ship ping in the actual fall-out area was not repeated on the GUVO shct, Further the 120 to 200 NM strip within the search capability of a single P2V aircraft was found not commensurate with the variations whieh could occur in the fore~ cast winds from D minus 2 days forward threugh shot time. More than one P2V aireraft making parallel sweeps, eithough s scoswhat better solution, was still not the answer. The dominant fact that became apparent was that a larg: area was involved in order to be assured of cowering the variation in the forecast winds, the diffusion of the cloud along its path of travel, anc changes in direction of drift of the cloud at points cutside the influence of ground sero winds. For this reason, subsequent to BR:VO, the search plan was modified to intensively search area (defined above) with three P2Zv aircraft on D mims 1 day, and-to make a paralfel search with two P2V aircraft! out to 600 NM (and 240 NM wide) centered on the forecast dirsetion of signifl. cant fall-out. The eapability was also maintained ani used on some shots, to search on Day Day in advance of the clow. « further modification was made for the one shot at END-ETOK to avoid excessive drain on aircraft availability due to numerous shot cancellations. .n area EVELYN was defined as a sector centered on-the ZNIWETOK Lagoon, 270° clockwise through north to 90°, radius -300 NM, plus w rectangular strip 60 NM wide and 600 NM long icmediateal adjacent to the south. Since the normal air particle trajectories gonerally moved toward the east as indicated in 4.4(1) above, the search of this smalle erea, which could be secomplished faster (and therefore at a later starting tine before H-hour) and with less aircraft, took advantage of the relatively Clear easternmost portion of the 450 NM Oanger area without the necessicy for 34