Narrative:

Dispatched with right pack inoperative, because of inability to control. The cabin temperature seemed to be cooling on the ground with the left pack only. After takeoff, we were hoping to see a drop in cabin temperature, but it did not, and we were busy troubleshooting. We had briefed single pack operation and to be aware of pressurization, and it seemed to be working fine, slight climb after takeoff 300 FPM. Next, we got a 'cargo det air' status message and ran the emergency checklist. That problem was corrected and we returned to the temperature. I had leveled off and was planning to return to lax, but thought we would give maintenance a call for a last idea. Maintenance said to reinstate the right pack. At about that time we received a 'cabin altitude warning.' we declared an emergency, and started to descend. With both packs operating, the cabin was stable and started to descend from 9500 ft. Within 3 mins the cabin warning was gone as cabin was now below 8000 ft. We returned to lax with a successful overweight landing 292000 pounds. The cabin also started to cool down with the right pack back on. Neither the first officer nor myself felt any discomfort in our ears or other signs of a pressurization problem. The hot day at lax, and temperature control problem, and cargo det air message took our attention away from the cabin altitude, and I can only speculate that there was some unknown problem causing the cabin to climb the whole time. Cabin altitude reached 9500 ft that I saw, and then because they felt dizzy, the #3 flight attendant was unable to walk off the aircraft, and was taken to medical. We switched aircraft and continued to jfk. In retrospect, the aircraft should have been cooling sooner.

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Original NASA ASRS Text

Title: B767 FLC HAS 'CABIN ALT WARNING' DURING CLB, DECLARES EMER AND RETURNS TO KLAX.

Narrative: DISPATCHED WITH R PACK INOP, BECAUSE OF INABILITY TO CTL. THE CABIN TEMP SEEMED TO BE COOLING ON THE GND WITH THE L PACK ONLY. AFTER TKOF, WE WERE HOPING TO SEE A DROP IN CABIN TEMP, BUT IT DID NOT, AND WE WERE BUSY TROUBLESHOOTING. WE HAD BRIEFED SINGLE PACK OP AND TO BE AWARE OF PRESSURIZATION, AND IT SEEMED TO BE WORKING FINE, SLIGHT CLB AFTER TKOF 300 FPM. NEXT, WE GOT A 'CARGO DET AIR' STATUS MESSAGE AND RAN THE EMER CHKLIST. THAT PROB WAS CORRECTED AND WE RETURNED TO THE TEMP. I HAD LEVELED OFF AND WAS PLANNING TO RETURN TO LAX, BUT THOUGHT WE WOULD GIVE MAINT A CALL FOR A LAST IDEA. MAINT SAID TO REINSTATE THE R PACK. AT ABOUT THAT TIME WE RECEIVED A 'CABIN ALT WARNING.' WE DECLARED AN EMER, AND STARTED TO DSND. WITH BOTH PACKS OPERATING, THE CABIN WAS STABLE AND STARTED TO DSND FROM 9500 FT. WITHIN 3 MINS THE CABIN WARNING WAS GONE AS CABIN WAS NOW BELOW 8000 FT. WE RETURNED TO LAX WITH A SUCCESSFUL OVERWT LNDG 292000 LBS. THE CABIN ALSO STARTED TO COOL DOWN WITH THE R PACK BACK ON. NEITHER THE FO NOR MYSELF FELT ANY DISCOMFORT IN OUR EARS OR OTHER SIGNS OF A PRESSURIZATION PROB. THE HOT DAY AT LAX, AND TEMP CTL PROB, AND CARGO DET AIR MESSAGE TOOK OUR ATTN AWAY FROM THE CABIN ALT, AND I CAN ONLY SPECULATE THAT THERE WAS SOME UNKNOWN PROB CAUSING THE CABIN TO CLB THE WHOLE TIME. CABIN ALT REACHED 9500 FT THAT I SAW, AND THEN BECAUSE THEY FELT DIZZY, THE #3 FLT ATTENDANT WAS UNABLE TO WALK OFF THE ACFT, AND WAS TAKEN TO MEDICAL. WE SWITCHED ACFT AND CONTINUED TO JFK. IN RETROSPECT, THE ACFT SHOULD HAVE BEEN COOLING SOONER.

Data retrieved from NASA's ASRS site as of July 2007 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.