Narrative:

Flight to ZZZ1 was the 3RD leg of the day; day 3 of a 4 day trip. My first officer is a new hire with less than 100 hours. All previous flts were uneventful. Push was normal with all preflight checklists accomplished. The special departure was fully briefed and flight was flown as captain's leg. The climb checklist at 10000 ft indicated no abnormal pressurization problems. Departure and initial climb were uneventful. Climbing through FL300 for FL330 the cabin altitude warning horn sounded. I noted that the cabin altitude was at 10000-11000 ft but no pressurization panel or master caution lights were illuminated. Cabin altitude was climbing at approximately 500 FPM. We donned our oxygen masks; established communications; declared an emergency and initiated an emergency descent almost simultaneously. I had the first officer complete the cabin altitude warning horn/abnormal pressurization and emergency descent checklists while I coordinated with center. I then had the first officer tell the flight attendants that we had a pressurization problem and that we were descending to a lower altitude. We leveled at 9000 ft MSL; removed our oxygen masks and reviewed the QRH checklists. During the descent; the cabin altitude did not go above approximately 11000 ft MSL so the passenger's oxygen masks did not deploy automatically; nor did we deploy them manually. The first officer then noticed that the land altitude set for the arrival airport (ZZZ1); and the cabin altitude were both set incorrectly. The ZZZ1 airport elevation is approximately 1100 ft MSL and the land and cabin altitude had been inadvertently set to 11130 ft MSL. I concluded that the abnormal pressurization was a result of the incorrect land and cabin altitudes. We dialed in the correct land and cabin altitudes and returned to the automatic mode from manual mode and the cabin began to pressurize normally. We reviewed our fuel situation and determined there was sufficient fuel to safely proceed to our scheduled destination (ZZZ1). En route to ZZZ1 we coordinated with ZZZ1 operations and maintenance regarding the abnormal pressure event. I also briefed the flight attendants and passenger that we had experienced an abnormal pressurization and that we would be flying the remaining portion of the flight at a lower altitude and that we had sufficient fuel to do so. The remainder of the flight to ZZZ1 was uneventful. All descent; landing and parking checklists were completed normally. After debrief with the flight attendants; they indicated no passenger seemed to experience any discomfort during the descent or remaining portion of the flight. At the gate I notified dispatch and the chief pilot.

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Original NASA ASRS Text

Title: A B737-300 FLT CREW DECLARED AN EMER AND EXECUTED AN EMER DSCNT IN RESPONSE TO A CABIN ALT WARNING HORN. THE EXCESSIVE CABIN ALT WAS DUE TO A MISSET PRESSURIZATION PANEL.

Narrative: FLT TO ZZZ1 WAS THE 3RD LEG OF THE DAY; DAY 3 OF A 4 DAY TRIP. MY FO IS A NEW HIRE WITH LESS THAN 100 HRS. ALL PREVIOUS FLTS WERE UNEVENTFUL. PUSH WAS NORMAL WITH ALL PREFLT CHKLISTS ACCOMPLISHED. THE SPECIAL DEP WAS FULLY BRIEFED AND FLT WAS FLOWN AS CAPT'S LEG. THE CLB CHKLIST AT 10000 FT INDICATED NO ABNORMAL PRESSURIZATION PROBS. DEP AND INITIAL CLB WERE UNEVENTFUL. CLBING THROUGH FL300 FOR FL330 THE CABIN ALT WARNING HORN SOUNDED. I NOTED THAT THE CABIN ALT WAS AT 10000-11000 FT BUT NO PRESSURIZATION PANEL OR MASTER CAUTION LIGHTS WERE ILLUMINATED. CABIN ALT WAS CLBING AT APPROX 500 FPM. WE DONNED OUR OXYGEN MASKS; ESTABLISHED COMS; DECLARED AN EMER AND INITIATED AN EMER DSCNT ALMOST SIMULTANEOUSLY. I HAD THE FO COMPLETE THE CABIN ALT WARNING HORN/ABNORMAL PRESSURIZATION AND EMER DSCNT CHKLISTS WHILE I COORDINATED WITH CENTER. I THEN HAD THE FO TELL THE FLT ATTENDANTS THAT WE HAD A PRESSURIZATION PROB AND THAT WE WERE DSNDING TO A LOWER ALT. WE LEVELED AT 9000 FT MSL; REMOVED OUR OXYGEN MASKS AND REVIEWED THE QRH CHKLISTS. DURING THE DSCNT; THE CABIN ALT DID NOT GO ABOVE APPROX 11000 FT MSL SO THE PAX'S OXYGEN MASKS DID NOT DEPLOY AUTOMATICALLY; NOR DID WE DEPLOY THEM MANUALLY. THE FO THEN NOTICED THAT THE LAND ALT SET FOR THE ARR ARPT (ZZZ1); AND THE CABIN ALT WERE BOTH SET INCORRECTLY. THE ZZZ1 ARPT ELEVATION IS APPROX 1100 FT MSL AND THE LAND AND CABIN ALT HAD BEEN INADVERTENTLY SET TO 11130 FT MSL. I CONCLUDED THAT THE ABNORMAL PRESSURIZATION WAS A RESULT OF THE INCORRECT LAND AND CABIN ALTS. WE DIALED IN THE CORRECT LAND AND CABIN ALTS AND RETURNED TO THE AUTO MODE FROM MANUAL MODE AND THE CABIN BEGAN TO PRESSURIZE NORMALLY. WE REVIEWED OUR FUEL SITUATION AND DETERMINED THERE WAS SUFFICIENT FUEL TO SAFELY PROCEED TO OUR SCHEDULED DEST (ZZZ1). ENRTE TO ZZZ1 WE COORDINATED WITH ZZZ1 OPS AND MAINT REGARDING THE ABNORMAL PRESSURE EVENT. I ALSO BRIEFED THE FLT ATTENDANTS AND PAX THAT WE HAD EXPERIENCED AN ABNORMAL PRESSURIZATION AND THAT WE WOULD BE FLYING THE REMAINING PORTION OF THE FLT AT A LOWER ALT AND THAT WE HAD SUFFICIENT FUEL TO DO SO. THE REMAINDER OF THE FLT TO ZZZ1 WAS UNEVENTFUL. ALL DSCNT; LNDG AND PARKING CHKLISTS WERE COMPLETED NORMALLY. AFTER DEBRIEF WITH THE FLT ATTENDANTS; THEY INDICATED NO PAX SEEMED TO EXPERIENCE ANY DISCOMFORT DURING THE DSCNT OR REMAINING PORTION OF THE FLT. AT THE GATE I NOTIFIED DISPATCH AND THE CHIEF PLT.

Data retrieved from NASA's ASRS site as of January 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.