III rehearsals were conducted: . 153 seven for YUCCA, on 21 and 25 March andl, 5, 8, 14, and 18, April; four for CACTUS, on 16, 18, 22, and 28 April; one for SYCAMORE, on 15 April; and one for FIR, on 17 April. A dual shot rehearsal involved the CACTUS and YUCCA missions on 18 April 1958. These rehearsals were extremely beneficial to Task Group 7.4 for several reasons, Many persons having important missions during shot périods (for axampie, sampler crews and air controllers) were able to gain valuable experience during the rehearsals and, thus, were well pre= pared for actual test operetions. Hany and varied difficulties with equip- ment were discovered and eliminated before the test period was inaugurated, Furthermore the renearsal period permitted a thorough checkout of the various operational systems and a closer familiarity of personnel with equicment, as well as it made possible an efficient integration of all Task Grour 7.4 elements, &. SHOTS AND AIRCRAFT PARTICIPATION Tnroughout the rehearsals and 35 shots on Operation HANDTACK, the aircraft senedulisg, mission execution, and aircraft recovery proceeded witnout major difficulty. For those missions which cu)minated in an actual snot,-33.9 per cent of all aircraft scheduled to participate maue goud their missions. xUcUA, The first snct of the 1958 nuclear test series was YUUUA, if _—