= t At midnight on D-l day, the Air Operations Center checks. began their By H minus four hours, the Center was completely manned, including the Task Group Commander, Operations Officer, air controllers, and Communications Officer. At approximately H minus three hours, the Tower Officer was in place serving as an advisor and coordinator for test array aircraft. At 0310, STABLE ECHO started engines, taxied at 0315 and took off at 0335 hours. Each H-Hour array aircraft on the Mission Execution Chart followed at the assigned time until there were two (2) AdDs, two (2) FJ-4s, one (1) B-52, one (1) SA~16, one (1) B-57B Sampler Controller, one (1) B-57B Sampler, and a P2V airborne. Each of these aircraft was under control of the Air Operations Center and their positions were monitored by the air controllers. The effects aircraft (B-52, A4Ds, and FJ-4s) were primarily controlled by MSQ and M~-33 precision radars capable of very accurate positioning. The Air Operations Center provided back up positioning capability in the event of precision equipment malfunction. The AOC also had the overall responsibility for safe positioning of all aircraft. At H minus one hour, the voice countdown was broadcast over UHF "Guard" channel from ELMER Island and all aircraft had their radios positioned in the "Guard Receive" position, insuring that they were receiving the warnings prior to detonation. By H minus thirty minutes all aircraft airborne at H-Hour were in position. At H minus five (5) minutes, the Commander, Task Group 7.4 reported to the Commander, Joint Task Force SEVEN that all aircraft were safely positioned. All radio transmissions with the exception of emergencies and the voice countdown on Guard channel, were silenced from H minus three minutes until H plus two (2) minutes. At H plus two (2) minutes, the Air Operations Center called all aircraft for 152 AFWU/HO