Narrative:

The event was an uncontrollable cabin altitude which required a rapid descent to preserve cabin pressure. The aircraft was dispatched with an inoperative APU and subsequently, during taxi out, an inoperative left air conditioning pack. This resulted in only 1 air source for cabin pressure. A malfunction of the remaining air source system resulted in an unscheduled descent and landing. I felt the decision to land at rno was sound. However, the decision I made to accept the aircraft initially, while legal, could be questioned. I also think, in retrospect, the maintenance log write-up I made did not provide enough information to our maintenance personnel and future crew members. Supplemental information from acn 355017: had a pack problem on taxi out. Left pack was not working. On takeoff, the left bleed off light came on. It was turned off. The bleed off switch turned off as per checklist. We now had left pack off and left bleed off. Right pack on and bleed on. In cruise, we got the cabin altitude warning light and then the warning horn. We started an emergency descent. We also turned off track. The captain declared an emergency. As we were going down, he turned the left bleed and left pack back on. We then got control of the cabin back. We diverted to rno. After talking to air carrier maintenance and doing all the maintenance checks, we did not put an entry into the book. We just forgot.

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Original NASA ASRS Text

Title: AN ACR B757 CREW HAD A DIVERSION TO ALTERNATE AFTER AN ACFT EQUIP PROB LOSS OF PRESSURIZATION. EMER DECLARED.

Narrative: THE EVENT WAS AN UNCTLABLE CABIN ALT WHICH REQUIRED A RAPID DSCNT TO PRESERVE CABIN PRESSURE. THE ACFT WAS DISPATCHED WITH AN INOP APU AND SUBSEQUENTLY, DURING TAXI OUT, AN INOP L AIR CONDITIONING PACK. THIS RESULTED IN ONLY 1 AIR SOURCE FOR CABIN PRESSURE. A MALFUNCTION OF THE REMAINING AIR SOURCE SYS RESULTED IN AN UNSCHEDULED DSCNT AND LNDG. I FELT THE DECISION TO LAND AT RNO WAS SOUND. HOWEVER, THE DECISION I MADE TO ACCEPT THE ACFT INITIALLY, WHILE LEGAL, COULD BE QUESTIONED. I ALSO THINK, IN RETROSPECT, THE MAINT LOG WRITE-UP I MADE DID NOT PROVIDE ENOUGH INFO TO OUR MAINT PERSONNEL AND FUTURE CREW MEMBERS. SUPPLEMENTAL INFO FROM ACN 355017: HAD A PACK PROB ON TAXI OUT. L PACK WAS NOT WORKING. ON TKOF, THE L BLEED OFF LIGHT CAME ON. IT WAS TURNED OFF. THE BLEED OFF SWITCH TURNED OFF AS PER CHKLIST. WE NOW HAD L PACK OFF AND L BLEED OFF. R PACK ON AND BLEED ON. IN CRUISE, WE GOT THE CABIN ALT WARNING LIGHT AND THEN THE WARNING HORN. WE STARTED AN EMER DSCNT. WE ALSO TURNED OFF TRACK. THE CAPT DECLARED AN EMER. AS WE WERE GOING DOWN, HE TURNED THE L BLEED AND L PACK BACK ON. WE THEN GOT CTL OF THE CABIN BACK. WE DIVERTED TO RNO. AFTER TALKING TO ACR MAINT AND DOING ALL THE MAINT CHKS, WE DID NOT PUT AN ENTRY INTO THE BOOK. WE JUST FORGOT.

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.