XITT - The daily surveillance mission required coverage from 15 degrees north latitude (Philippines) to 55 degrees north latitude (tip of the Aleutians) at the 700-millibar and either the 100 or 500-millibar levels, Samplers directed two round-robin missions each day from Yokota, Japan, one northeast and one southwest, outbaund at one altitude and inbound on the alternate altitude. The purpose of the flights was to collect daily particulate samples emanating from the Asiatic mainland in order to detect possible nuclear events not otherwise picked up by the early warning system: The 926th Test Squadron also collected gaseous and particulate samples from each of the four separate latitudinal areas: north of Eielson Air Force Base, Alaska; Base, Texas; south of Yokota, Japan; north of Laughlin Air Force south of Andersen Air Force Base, Guam; and from East Sale, Australia, Samples were collected each 15 days at all four locations. On each alternate 15~day schedule, a modified profile sampling was made, During each May and November, the sampling program increased so as to obtain profile samples each week (five missions each month in lieu of the routine two missions per month for the other ten months ), Assumptions which guided the enlarged sampling program included, (a) A total of 35 foreign nuclear tests would be conducted annually, (b) Tests would be conducted at a rate of not more than two events in one seven-day period. (c) Tests would be conducted in series of not less than five events each series, (ad) The maximm sortie requirement for each foreign event was estimated to be two tropospheric flights and three stratospheric flights 281 SWEH ~2-003h, 9,60 AFWL/HO : wow?