Narrative:

Level at FL350; EICAS cabin altitude warning activated. (The left pack was on MEL.) all right pack indications were normal except that the cabin altitude was increasing through 11000 ft. The excessive cabin altitude/rapid depressurization procedure was initiated and completed. An emergency was declared with ATC. During the descent; under the provisions of my emergency authority/authorized; I elected to activate the MEL'ed left pack in order to regain control of the cabin altitude. The cabin altitude became ctlable and the EICAS cabin altitude warning extinguished. The aircraft was leveled at 10000 ft MSL. I checked with the flight attendants and there were no flight attendant or passenger issues. The oxygen masks did not deploy. I proceeded to coordination with dispatch and maintenance control. Based on the fuel on board; WX and the ctlability of the cabin altitude; a decision was made to continue to ZZZ. I made an announcement to the passenger regarding our situation. The remainder of the flight was uneventful. Upon arrival; I made an appropriate logbook entry. Flight crew cause/narrative: unknown. Flight crew suggestions/narrative: this was the first time I have accomplished an actual emergency descent in an aircraft. For yrs in the simulator; I have been putting my headset back on my head after I don the oxygen mask. I used this technique in the aircraft and it made communicating with ATC and also the first officer many times the clarity of trying to use the flight deck speakers.

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Original NASA ASRS Text

Title: B757 FLT CREW REPORTS CABIN ALTITUDE WARNING AT FL350 AND EMERGENCY DESCENT. ACFT DISPATCHED SINGLE PACK AND MEL'ED PACK IS USED DURING DESCENT TO POSITIVE EFFECT.

Narrative: LEVEL AT FL350; EICAS CABIN ALT WARNING ACTIVATED. (THE L PACK WAS ON MEL.) ALL R PACK INDICATIONS WERE NORMAL EXCEPT THAT THE CABIN ALT WAS INCREASING THROUGH 11000 FT. THE EXCESSIVE CABIN ALT/RAPID DEPRESSURIZATION PROC WAS INITIATED AND COMPLETED. AN EMER WAS DECLARED WITH ATC. DURING THE DSCNT; UNDER THE PROVISIONS OF MY EMER AUTH; I ELECTED TO ACTIVATE THE MEL'ED L PACK IN ORDER TO REGAIN CTL OF THE CABIN ALT. THE CABIN ALT BECAME CTLABLE AND THE EICAS CABIN ALT WARNING EXTINGUISHED. THE ACFT WAS LEVELED AT 10000 FT MSL. I CHKED WITH THE FLT ATTENDANTS AND THERE WERE NO FLT ATTENDANT OR PAX ISSUES. THE OXYGEN MASKS DID NOT DEPLOY. I PROCEEDED TO COORD WITH DISPATCH AND MAINT CTL. BASED ON THE FUEL ON BOARD; WX AND THE CTLABILITY OF THE CABIN ALT; A DECISION WAS MADE TO CONTINUE TO ZZZ. I MADE AN ANNOUNCEMENT TO THE PAX REGARDING OUR SITUATION. THE REMAINDER OF THE FLT WAS UNEVENTFUL. UPON ARR; I MADE AN APPROPRIATE LOGBOOK ENTRY. FLT CREW CAUSE/NARRATIVE: UNKNOWN. FLT CREW SUGGESTIONS/NARRATIVE: THIS WAS THE FIRST TIME I HAVE ACCOMPLISHED AN ACTUAL EMER DSCNT IN AN ACFT. FOR YRS IN THE SIMULATOR; I HAVE BEEN PUTTING MY HEADSET BACK ON MY HEAD AFTER I DON THE OXYGEN MASK. I USED THIS TECHNIQUE IN THE ACFT AND IT MADE COMMUNICATING WITH ATC AND ALSO THE FO MANY TIMES THE CLARITY OF TRYING TO USE THE FLT DECK SPEAKERS.

Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.