ABSTRACT At Operation REDWING, fallout sampling was conducted by arrays or groups of similar collecting instruments. Each array was located on the periphery of an elevated and circular wind-shielded platform designated as the standard platform. A correlation of the sampling variations in the amounts of fallout collected within the platforms was accomplished by the analysis of the collection data and the platform's air-flow characteristics. With a single-wind system the amount of fallout collected in the upwind part of the platform was lower than that collected in the downwind section and the collections around the platform varied symmetrically with respect to the wind direction. With a multi-wind system, similar characteristics were exhibited about a reference direction which was correlated to the variability of wind directions and asso- ciated fallout amounts by a vector summation. The extent of sampling variation or collection bias in both systems can be defined by certain parameters. For each platform the values ofthese parameters were obtained from the pro- perties of a collection curve describing the variation around the platforn. Collection curves of both systems were completed by interpolation and their notable aspect is that they resemble sine curves. At the only land station the sampling data between the platform collection and the associated collection on the ground was too limited for extrapolation to other systems. Sampling relationships between platform collection and associated ground eollection are described for the single-wind system butnot for the multi- wind system. At the ship stations the equivalentground value of the platform collections i.e., the value that would be collected by the earth's surface, could not be determined; however, the weighted mean values of some of these platform collections are presented. ii