barrier would be installed at Bikini only. An officer from FEAF arrived on 12 February to direct the installation of the barrier at Bikini. The structure was operational in time for the first full-scale rehearsal on 23 February .° Although no occasion arose for its use during CASTLE, the mere presence of the runway arresting barrier was a great morale factor, especially for the fighter pilots. I, EXERCISE TIGER/CAT During the latter months of 1953, the Air Task Group completed the ZI phase of its training and found workable solutions for the problems incurred in the procurement of men and materiel. Of interest in the operational phase of training was Operation TIGER/CAT, the ZI rehearsal for CASTLE. On 27 October 1953 Exercise TIGER/CAT was conducted from the San Diego Naval Air Station. This operation was held to check communica- tion and operational procedures between the Navy and Air Force operating units. Most of the discrepancies, forty-five in all, were minor, such as the absence of wing-walkers, improper parking arrangement, minor communications failures and poor coordination. Corrective action in all cases was noted in the Task Group 7.4 secret document entitled TIGER/CAT Discrepancies, TG 7.4 Control No. 3-1053S. Although several aircraft arrival and departure times varied slightly from the schedule, all times were considered operationally sound. Numerous problems arose that were the result of the work being performed by personnel who were complete strangers the day before the operation, but it was evident that a spirit of cooperation existed throughout the entire event. TIGER/CAT brought together personnel and aircraft from different branches of the service and from different organizations within the Air AIWI HT