169 III troublesome; however, these difficulties were overcome gradually, per- mitting « calibration and chec:-out of equipment, and on 6 April 1958, the air Operations Venter reached operational status, ever though a Lack of reyuired ultra nign frequency crystals still hampered the over-all use of the system, fhe lack of crystals eventually was overcome when Task Group 7.4 was aole to borrow a sufficient number from otner organizations in the proving yround. The maintenance of communications and electronics equipment oftey was deterred because of the 24 hour overation of the center. Mainte:.ance, Nowever, was performed as much as possible during non-test veriods, and this methoa ultimately proved to be adejuate. vespite inevitable supoly dirficulties, the deteriorating eifects of the proving ground climate, and the high rate of usage of available equipment, the air control system and its relate. conmunications systems were ade.juate -o meet the neeas of Task Uroup 7.4.. G. MAINTE ANCK Goat aGu fhe Maintenance vontrol unit, consisting of tne task group M intenance Officer and nine airmen, was estublished by tne Director of materiel soon after-arrival at eniwetok of the advance echelon, to assist tne aircraft maintenance organizations in performin,, tiie maintenance mission, . G AFWL/ HO