d“ ono: ala direction from ground zero varying with the expected yield of the de‘vice to be detonated. After the detonation, the controller watched the development of the nuclear cloud and observed its drift and configuration. The sampler aircraft took off at pre-determined times after H-Hour and were vectored toward the sampler controller by the Air Operations Center. The sampler controller then vectored the sampler aircraft into the cloud at the points where he expected to obtain the desired samples. The crews recorded radiation readings obtained on the special instruments and read them to the scientific controller, who took this information on both a written record and ona tape recorder, The requirements of the scientific laboratories were met in most cases during HARDTACK, At some times weather conditions prevented maximum results from being obtained, On other shots, failure of the device to perform as predicted made changes of altitude necessary to obtain suitable samples, Figure }, illustrates nuclear test events; the desired fissions to be obtained in the samples and the results obtained. All bars to the right of the required fissions line indicates a sample as great or greater than required. Bars to the left show sample sizes smaller than desired, 6 In planning for Operation HARDTACK, the aircrew requirements for sampler aircraft were computed on the basis of the number of nuclear clouds to be sampled and the amount of radiation exposure that the crew members were to get in obtaining the desired sample, The inclusion of several ad- ditional shots to the program and the miscalculation of exposures on certain shots resulted in some aircrew members receiving maximum exposures before the end of the operation, This necessitated the replacement of some of the Be57 pilots and the training of additional observers from volunteers among Task Group 7.4 rated personnel, AFwi /Ha Figure 5 shows the radiation exposure of . gh