ACR HAS CABIN PRESSURE CLB AT BEGINNING OF DSCNT. EMER DSCNT MADE AFTER RESPONSE TO TCASII.

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FL370 WITH DISCRETION TO FL240 CABIN PRESSURE STARTED CLBING AT MAX RATE FOR NO REASON. PUT MASK ON AND STARTED DSCNT WHILE FO TRIED TO CLOSE OUTFLOW VALVE. I MADE A MISTAKE AND FAILED TO FLIP MY MICROPHONE MASK SWITCH TO MASK; AND WAS UNABLE TO COM WITH FORT WORTH. THINKING I MAY HAVE A SECOND PROBLEM (RADIOS) I SQUAWKED 7700; THEN WAITED FOR AN AIRPLANE TO CLR ON TCASII (15-30 SECONDS); THEN CONTINUED THE DSCNT; FINALLY REALIZING MY MISTAKE AND FLIPPING THE SWITCH TO COM WITH FORT WORTH ARTCC. LEVELED AT 10000 FT AND ONCE FLT ATTENDANTS RPTED ALL OK; CANCELLED EMER. RECOMMENDATIONS: I ADMITTED MY MISTAKE TO COMPANY SO THEY COULD EMPHASIZE THE MASK SWITCH TO OTHERS. PROC NOW SAYS 'ESTABLISH COM' WHICH I THOUGHT I HAD DONE RATHER PROFOUNDLY WHEN I SCREAMED CLOSE THE OUTFLOW VALVE AT THE FO JUST AS I PUT MY MASK ON. MY NEW PROC IS FLIP THE SWITCH AND ESTABLISH COM. SUPPLEMENTAL INFO FROM ACN 204276: DUE TO HIGH WORKLOAD; THE APCH DSCNT CHKLIST WAS COMPLETED AT 10000 FT AND NOT 18000 FT; AND THE FINAL DSCNT CHKLIST WAS COMPLETED AT APPROX 700 FT AGL BEFORE LNDG. NEVER SAW CABIN ABOVE 16000 FT.