AN ACR FLC PERFORMED AN EMER DSCNT AFTER A B727 CABIN PRESSURE WARNING HORN SOUNDED.

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LOST CABIN PRESSURIZATION CTL WHILE AT CRUISE AT FL370. CALLED CTR; WAS TOLD TO STANDBY. SAID NEGATIVE; WE LOST THE CABIN; WAS BEGINNING AN EMER DSCNT; NOW; AND WOULD TURN 45 DEGS OFF OF AIRWAY; EITHER WAY; HIS CHOICE. DID NOT HEAR FROM HIM IMMEDIATELY SO WE TURNED R; AND BEGAN DSCNT. THEN WE WERE CLRED TO FL240. HOWEVER CABIN WAS STILL UNCTLED AND WE NEEDED LOWER. WE TOLD HIM THIS AND WENT THROUGH FL240 TO ABOUT FL230 BEFORE HE ISSUED 11000 FT. WE LATER VERIFIED THAT WE HAD DECLARED AN EMER; ALTHOUGH THE CTLR SAID NOTHING. I WAS JUST CONCERNED ABOUT BUSTING AN ALT DURING AN EMER SIT. THERE WAS NO CONFLICT WITH OTHER TFC; AND CTLR SEEMED TO NOT NOTICE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE FLC INITIALLY LOOKED FOR OTHER CAUSES; WHEN THE WARNING HORN SOUNDED. FO STATES THAT PRESSURIZATION LOSS IS VERY UNUSUAL FOR B727-200'S AND THEY FIRST CHKED OTHER SYS THAT ARE INTEGRATED WITH A WARNING HORN. FOR SOUND REASONS THE FLC FOLLOWED SOP'S EVEN THOUGH THE CABIN LEAK WAS VERY SLOW.