0018933 13-14 hours had’ to be cancelled due to rain and atmospheric turbulence. The first four samples were collected in about 1/2 hour each and the last sample required 2-1/2 hours, The wing tank samplers functioned on each flight, but there were no gas samples on the last three runs due to a failure of the compressor pumps on the coincident sampling units, Samples of material falling from the 60,000 foot layer were collected at an altitude of 1000 feet at 4, 6, 8, 10 and 12 hours after shot time bya _ WB-50 aircraft, at 28, 59, 88, The fallout was encountered on a bearing of 50-60 degrees 109 and 131 miles from ground zere, A second WB-50 collected one 1000-foot sample at H # 6 hours on a bearing of 20 degrees at 42 miles from ground zero, 45,000 feet. Itis thought that this mzterial came from about A third WB-50 missica was flown at 0700 the next day to 300 miles on bearing 58 degrees based on an extrapolation of the previous contacts. From there, the aircraft was directed to 225 miles, bearing 55 degrees, then to 200 miles, bearing 40 degrees, and finally to 400 miles, 60 degrees, but no fallout was encountered, The aircraft was released after 6 hours for a weather mission, Shot Fir, — was fired at Bikini cn the day preceding Koa and the clouds from the two bursts rose to approximately the same height (65,000 feet). On the day following Koa there wés a deposition of fallout in the Eniwetok area and in the afternoon the gamma radiation background on