Narrative:

Enclosed attached is a report submitted to air carrier. Additional information is as follows. Both crew members had flown together for the previous 4 weeks. Flight schedule was heavy during this time. Both crew members remarked on leg prior to this leg that they were tired. In fact, they were both exhausted. Crew had a 30 hour in 7 days legality conflict. So they were deadheaded on first leg of day to reduce block time and stay under the 30 in 7 legal limit. This action by company complied with the letter of the law, but not the intent (to provide adequate rest to crew members). First officer failed to turn on pack switches to pressurize aircraft and captain failed to notice this omission on his after takeoff checklist. Aircraft was very air tight so the cabin only climbed at approximately half the rate of climb of the aircraft. Crew attention was interrupted several times during pushback, start-up, and taxi phases of flight. Crew's attention was further diverted to work with a faulty indication in a gauge for another system. Approaching 31000 ft the cabin altitude warning horn went off and shortly thereafter cabin altitude climbed from 10000 ft (horn) to 13500 ft and cabin oxygen masks deployed. Upon getting the cabin warning horn, both crew members checked the pressurization controller but still did not notice the pack switches in the off position. An emergency descent was initiated, aircraft leveled off at 10000 ft and returned to originating station. Both crew members agree that the bottom line cause of this incident is crew member fatigue. Company is unwilling to admit their scheduling practices are contributory in any way.

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Original NASA ASRS Text

Title: EMER DSCNT INITIATED IN ACR MLG AFTER LOSS OF CABIN PRESSURE. RETURN LAND IN A DIVERSION TO ALTERNATE.

Narrative: ENCLOSED ATTACHED IS A RPT SUBMITTED TO ACR. ADDITIONAL INFO IS AS FOLLOWS. BOTH CREW MEMBERS HAD FLOWN TOGETHER FOR THE PREVIOUS 4 WKS. FLT SCHEDULE WAS HVY DURING THIS TIME. BOTH CREW MEMBERS REMARKED ON LEG PRIOR TO THIS LEG THAT THEY WERE TIRED. IN FACT, THEY WERE BOTH EXHAUSTED. CREW HAD A 30 HR IN 7 DAYS LEGALITY CONFLICT. SO THEY WERE DEADHEADED ON FIRST LEG OF DAY TO REDUCE BLOCK TIME AND STAY UNDER THE 30 IN 7 LEGAL LIMIT. THIS ACTION BY COMPANY COMPLIED WITH THE LETTER OF THE LAW, BUT NOT THE INTENT (TO PROVIDE ADEQUATE REST TO CREW MEMBERS). FO FAILED TO TURN ON PACK SWITCHES TO PRESSURIZE ACFT AND CAPT FAILED TO NOTICE THIS OMISSION ON HIS AFTER TKOF CHKLIST. ACFT WAS VERY AIR TIGHT SO THE CABIN ONLY CLBED AT APPROX HALF THE RATE OF CLB OF THE ACFT. CREW ATTN WAS INTERRUPTED SEVERAL TIMES DURING PUSHBACK, START-UP, AND TAXI PHASES OF FLT. CREW'S ATTN WAS FURTHER DIVERTED TO WORK WITH A FAULTY INDICATION IN A GAUGE FOR ANOTHER SYS. APCHING 31000 FT THE CABIN ALT WARNING HORN WENT OFF AND SHORTLY THEREAFTER CABIN ALT CLBED FROM 10000 FT (HORN) TO 13500 FT AND CABIN OXYGEN MASKS DEPLOYED. UPON GETTING THE CABIN WARNING HORN, BOTH CREW MEMBERS CHKED THE PRESSURIZATION CTLR BUT STILL DID NOT NOTICE THE PACK SWITCHES IN THE OFF POS. AN EMER DSCNT WAS INITIATED, ACFT LEVELED OFF AT 10000 FT AND RETURNED TO ORIGINATING STATION. BOTH CREW MEMBERS AGREE THAT THE BOTTOM LINE CAUSE OF THIS INCIDENT IS CREW MEMBER FATIGUE. COMPANY IS UNWILLING TO ADMIT THEIR SCHEDULING PRACTICES ARE CONTRIBUTORY IN ANY WAY.

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.