AN EMB135 FLC USES COMMAND AUTH WHEN DECLARING AN EMER FOR AN EMER DSCNT. ATC RESPONSE WAS TOO SLOW FOR LOWER ALT DUE TO TFC AFTER LOSS OF CABIN PRESSURE AT FL240 ON FREQ WITH ZFW; TX.

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AT APPROX XA22Z ON JUN/FRI/01 AT AN ALT OF FL240 NEAR ARDMORE; OK; ZFW VECTORED US TO A HDG OF 250 DEGS. WE WERE ON BOARD EMB135. THE ACFT HAD 1 PACK MEL'ED INOP. THE ACFT NORMALLY HAS 2 PACKS OPERATIONAL. THE REMAINING PACK VALVE CLOSED CAUSING THE CABIN ALT TO RISE. WE WERE UNABLE TO RESET THE PACK. AS A RESULT THE CABIN ALT AROSE TO 11000 FT AND WAS CLBING. CREW REQUESTED CLRNC TO 10000 FT. HOWEVER; ATC TOOK LONGER THAN WE WANTED TO STAY AT FL240. AN EMER WAS DECLARED. CREW EXERCISED MEMORY ITEMS FOR CABIN PRESSURIZATION BEING LOST AND EMER DSCNT. WE DSNDED TO 10000 FT; A DEV OF CLRNC. I AM SURE WE IMPACTED ARRS INTO DFW; BUT NO EVASIVE ACTION WAS TAKEN BY ANY OTHER ACFT AT 10000 FT. WE CONTINUED TO HOUSTON AND AN UNEVENTFUL LNDG WAS MADE. NO ACFT DAMAGE. NO CABIN OR CREW MEMBER INJURIES. CONTRIBUTING FACTORS: MAINT HAVING 1 OPERATIONAL PACK. ATC'S CONCERN FOR INBOUND TFC -- DULY NOTED AND UNDERSTOOD. ACFT WAS GIVEN TO MAINT TO REPAIR PACKS AND PRESSURIZATION SYS AND TO INSPECT ACFT FOR DAMAGE. ALL CHKLISTS WERE COMPLIED WITH. CREW EXERCISED ALL ACTIONS AND PERFORMED IN ACCORDANCE WITH TRAINING STANDARDS FOR SUCH AN EVENT TO KEEP PAX SAFE. RECOMMENDATION: EICAS MESSAGES WHEN OPERATING ON 1 PACK SHOULD BE A CAUTION MESSAGE IF BOTH PACK VALVES CLOSE. IF WE WOULD HAVE HAD A CAUTION MESSAGE 'PACK 1-2 VALVE CLOSED' WE COULD HAVE HAD MORE TIME TO DSND!