AN AERIAL SURVEY HELI PLT ENTERS THE FRINGE OF THE CLASS D OF SAC PRIOR TO RECEIVING CLRNC DUE TO PAX NOISE LEVELS IN COCKPIT NEAR SAC; CA.

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DURING AERIAL SURVEY (PART 91) PLT; TRYING TO FOLLOW RAPIDLY CHANGING INSTRUCTIONS FROM PAX AS TO WHICH DIRECTION THEY WANTED TO GO; WAS ASKED TO TURN E TOWARD SAC. AT 5 MI OUT I CONTACTED TWR TO ASK FOR TRANSITION THROUGH SAC CLASS D. AS TWR BEGAN REPLY WITH ACFT CALL SIGN; PAX BEGAN TALKING AND DROWNED OUT TWR INSTRUCTIONS. PLT THEN CUT OFF PAX MIKES AND CALLED TWR FOR REPETITION OF INSTRUCTIONS. TWR ASKED FOR ACFT POS AGAIN; THAT ACFT HADN'T BEEN CLRED IN. PLT BEGAN TIGHT; LOW LEVEL HOLDING ORBIT AT THAT TIME 3.5-4 MI FROM SAC TILL BOTH TWR AND ACFT CONFIRMED COMS AND ACFT INSTRUCTIONS. PAX WERE KEPT SILENT THROUGHOUT SHORT PERIOD OF CONFUSION. NO OTHER ACFT IN VICINITY. PLT MISUNDERSTOOD THAT TWR HADN'T CLRED ACFT INTO CLASS D. HUMAN PERFORMANCE CONSIDERATIONS: IN FUTURE WILL LEAVE VHF AUDIO ON FOR PAX SO THEY KNOW TO KEEP QUIET. CORRECTIVE ACTIONS: PLT COMPLIED WITH ALL INSTRUCTIONS FROM TWR AND TOOK OWN INITIATIVE TO AVOID CAUSING UNSAFE SIT FOR TWR. THINK THAT FOR TWR EXTENT OF PROB WAS THAT FOR A MOMENT IT DIDN'T KNOW EXACT LOCATION OF THIS ACFT. IDENT AND LOCATION OF ACFT WAS QUICKLY ESTABLISHED BY BOTH PARTIES. PAX WERE BRIEFED AHEAD OF TIME NOT TO TALK WHILE PLT WAS IN COMS WITH ATC. ON ONE HAND; HELI PLTS FLYING LOW AND SLOW TRY TO AVOID ADDING TO COMS LOAD OF ATC IF WE CAN STAY OUT OF THEIR AIRSPACE. NORMALLY ON XCOUNTRY FLT PLT WOULD NORMALLY CALL UP TWR 10 MI OUT. TODAY'S FLT INVOLVED RAPID AND NUMEROUS COURSE CHANGES WHICH WOULD HAVE ADDED TO TWR'S BURDEN IF WE'D CHKED IN BEFORE IT WAS ABSOLUTELY NECESSARY. APPRECIATE TWR'S PATIENCE. CTLR WAS PROFESSIONAL AND COMPETENT.