AN ACR MLG OVERSHOT ITS ALT ON DSCNT. THERE WAS A TCASII ALERT GOING ON AT THE SAME TIME.

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IN DSCNT CLRNC TO FL220; FROM FL240; WE WERE TOLD THAT CLT VOR WAS OTS. ZTL GAVE HDG OF 190 DEGS FROM 130 DEGS. WE WERE ABOUT TO PENETRATE CLOUD LAYER BELOW. IN A VERY FAST 10-15 SECONDS THE FOLLOWING HAPPENED. I; THE PNF; WENT OFF FREQ TO CHK CLT ATIS AND; ALMOST SIMULTANEOUSLY; TCASII GAVE TA RED ARC TO APPROX 900 FT. THE FO DISCONNECTED AUTOPLT AT APPROX FL234. RATE OF DSCNT INCREASED TO 4000 FPM TO STAY OUT OF RED ARC. THEN ALL RED AND RESOLUTION TO CLB AT APPROX 500 FPM. BY THE TIME CLB STARTED; WE WERE AT FL211 OR FL212. ALT ALERTER AURAL WARNING OVERRIDDEN TWICE BY THE LOUDNESS OF RA. QUERIED ATC OF POTENTIAL TFC CONFLICT. DUE TO SPDS AND NOISE AND AFTER QUESTIONING ATC ABOUT TCASII TA/RA; THE TFC THEY CALLED CONFLICTED WITH OUR SCOPE. BY THE TIME WE RECTIFIED THE WHOLE SEQUENCE; FOLLOWING FAA APPROVED COMPANY TCASII PROCS; WE SHOT THROUGH OUR ASSIGNED ALT (MANUALLY FLYING) BECAUSE THE AIR NOISE AND TCASII TA/RA NOISE OVERRODE THE ALT WARNING HORN (1000 FT BEFORE LEVEL OFF AND 400 FT BELOW ASSIGNED ALT).