Narrative:

Scheduled flight from tul-oma. Normal takeoff and climb. During climb out I (F.O and PF) noticed the left duct pressure low and queried the captain. He replied not to bother about it. The day before we had had a problem with the takeoff warning horn on the ground at another station on the same aircraft. At TOC I was pulling the power back to cruise when we heard an intermittent warning horn. Both the altitude warning (cabin above 10000' MSL) and the takeoff warning sound the same. The captain pulled the aural warning circuit breaker. I thought this was odd so I scanned the overhead panel. I immediately noticed the cabin climbing at 2000 FPM and the cabin altitude at 10500'. I immediately asked the captain to request a lower altitude and I started a descent down. We cleared to 24000' then 18000' then 10000'. At 10000' we trouble shoot and we were able to get sufficient pressure to the cabin. Since we were tankering fuel and the WX was good in den (our mx base), I, at the request of the captain, requested a climb to 18000' (while monitoring the cabin) and a course for den. The captain made a conference call to company dispatch, mechanics. Mechanics wanted the aircraft in den, dispatch said it initially wanted us to continue to oma but ok to go to den, since we had the fuel. Dispatch later called back on company frequency to ask again if we would go to oma, but we decided to stick to our original plan and not to keep changing it. Dispatch later agreed. We continued to climb to FL260 and continued to den. The captain never declared an emergency. We both had a case of get 'homeitis', and felt we would have been stuck in oma. I feel decision to go to den was sound, due to WX, mechanics and passengers needs. Safety was never a risk. I do recommend the takeoff warn and cabin warning horn being changed. This is the second time I have been 'fooled' by this horn.

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Original NASA ASRS Text

Title: LOSS OF CABIN PRESSURIZATION. DESCENDED TO LOWER ALT WITH CLRNC.

Narrative: SCHEDULED FLT FROM TUL-OMA. NORMAL TKOF AND CLB. DURING CLBOUT I (F.O AND PF) NOTICED THE L DUCT PRESSURE LOW AND QUERIED THE CAPT. HE REPLIED NOT TO BOTHER ABOUT IT. THE DAY BEFORE WE HAD HAD A PROB WITH THE TKOF WARNING HORN ON THE GND AT ANOTHER STATION ON THE SAME ACFT. AT TOC I WAS PULLING THE PWR BACK TO CRUISE WHEN WE HEARD AN INTERMITTENT WARNING HORN. BOTH THE ALT WARNING (CABIN ABOVE 10000' MSL) AND THE TKOF WARNING SOUND THE SAME. THE CAPT PULLED THE AURAL WARNING CB. I THOUGHT THIS WAS ODD SO I SCANNED THE OVERHEAD PANEL. I IMMEDIATELY NOTICED THE CABIN CLBING AT 2000 FPM AND THE CABIN ALT AT 10500'. I IMMEDIATELY ASKED THE CAPT TO REQUEST A LOWER ALT AND I STARTED A DSNT DOWN. WE CLRED TO 24000' THEN 18000' THEN 10000'. AT 10000' WE TROUBLE SHOOT AND WE WERE ABLE TO GET SUFFICIENT PRESSURE TO THE CABIN. SINCE WE WERE TANKERING FUEL AND THE WX WAS GOOD IN DEN (OUR MX BASE), I, AT THE REQUEST OF THE CAPT, REQUESTED A CLB TO 18000' (WHILE MONITORING THE CABIN) AND A COURSE FOR DEN. THE CAPT MADE A CONFERENCE CALL TO COMPANY DISPATCH, MECHS. MECHS WANTED THE ACFT IN DEN, DISPATCH SAID IT INITIALLY WANTED US TO CONTINUE TO OMA BUT OK TO GO TO DEN, SINCE WE HAD THE FUEL. DISPATCH LATER CALLED BACK ON COMPANY FREQ TO ASK AGAIN IF WE WOULD GO TO OMA, BUT WE DECIDED TO STICK TO OUR ORIGINAL PLAN AND NOT TO KEEP CHANGING IT. DISPATCH LATER AGREED. WE CONTINUED TO CLB TO FL260 AND CONTINUED TO DEN. THE CAPT NEVER DECLARED AN EMER. WE BOTH HAD A CASE OF GET 'HOMEITIS', AND FELT WE WOULD HAVE BEEN STUCK IN OMA. I FEEL DECISION TO GO TO DEN WAS SOUND, DUE TO WX, MECHS AND PAXS NEEDS. SAFETY WAS NEVER A RISK. I DO RECOMMEND THE TKOF WARN AND CABIN WARNING HORN BEING CHANGED. THIS IS THE SEC TIME I HAVE BEEN 'FOOLED' BY THIS HORN.

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.