AR. ue thee be, Thic documeat qorrintte of Neo. [ BOX No. 182 (NN3 - 326 -V7-0/ ) ws f Or. 1. we pages Copies, Series 4 June 25, 1958 408831 FOLDER Mentteek,V Y Dear Mr. Durham: On February 13, 1958, I wrote you concerning the establishment of the danger area surrounding the atolls of Bikini and Eniwetok in connection with Operation HARDTACK. In the interim period it has become necessary to move the firing site for the two very high altitude shots to Johnston Island in order to insure that all safety criteria for these shots can be completely met. Therefore, it becomes necessary to establish a surface danger area surrounding Johnston Isiand which it is planned will be publicly announced on June 26, 1958, and which will become effective on July 25, 1958. Tt is hoped that the Johnston Island danger area can be disestablished on or about August 17, 1958, shortly after the firing of the last shot at Johnston Island. The surface danger area, as defined in the attached proposed notices, was determined after extensive studies of the eye damage problem which is associated with high altitude, large yield detonations. There is little or no radiological fallout problem associated with this type of shot. The operation at the Eniwetok Proving Ground will still be active during the period that the Johnston Island danger area is effective; hence, there will be two Pacific danger areas concurrently effective for an approximate three to four week period. Attached for your information is a proposed Notice to Mariners and a proposed public release on this subject. The Civil Aeronautics Administration will be advised by the Commander, Joint Task Force SEVEN when an air hazard exists requiring the interruption of aircraft flights. ‘This procedure will permit maximum use of the affected area during period when no danger exists. s . Wap eae ey soo . 4 pa Net he AN aS Se rr reneeeee No Lae pe i" ~ \ INIOL. CO , tae Drea 4 rh last iat he S}US1 epee td oye rey WN a, Sbls> am DBbai Sec anit ar .

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