Narrative:

Climbing out of 12;000 ft; the cabin altitude warning horn sounded. As I began to execute the cabin altitude warning horn immediate action items; I looked at the pressurization panel and noticed that both pack switches were in the off position. I discontinued the checklist after the first two steps; recognizing that the checklist would not resolve the problem. I directed the pilot flying to level the aircraft off at 12;000 ft; while I attained clearance to descend to 10;000 ft. Once clearance was received; I told the pilot flying that he had the aircraft and the radios; and I began trouble shooting the problem. During the descent; the aircraft began to exceed the programmed speed; so the auto throttles were turned off to keep the airspeed under control. I began executing the automatic fail/unscheduled pressurization change checklist. While running this checklist; we received an master caution/off scheduled descent indication. Resetting the mc system; I continued the af/upc checklist. Turning on the left pack switch to the on position; I didn't observe any change to the pressurization system (outflow valve full open; dp needle at 0; cabin altitude 10;000 ft.) I switched the pressurization mode selector switch to manual; and manually closed the outflow valve in increments until the aircraft began to pressurize normally. Passing below an 8;000 foot cabin altitude; I moved the right pack switch to the auto position and moved the outflow valve the rest of the way to the full closed position. I had the pilot flying request a climb to 12;000 for extra terrain clearance and began to execute the off scheduled descent checklist. When that checklist was complete; I switched the pressurization mode selector switch to the altn position; once I could see it was pressurizing normal; I switched it to the automatic position. Confirming that it was pressurizing normal; I resumed normal pilot not flying duties; requested a normal climb out to cruise altitude. We reset the flight altitude indicator to normal cruise altitude and made sure all checklists were complete and closed.we; as a crew; missed a checklist item three times. Interruption/distraction & high workload/task saturation: the takeoff roll and initial climb was very bumpy and took a lot of crosswind control to maintain ground track. After take off; we had to turn to a 050 heading; change radio frequencies; execute the climb checklist; acknowledge and execute a change to our cleared altitude and way point; all in quick succession. Interruption/distraction: a. I noticed the wind was howling as we entered the aircraft (the R1 door was open) and I was preoccupied that we either get turned into the wind or use the max motoring procedure for engine start. B. Two other minor issues preoccupied me on taxi out; 1. The aircraft required higher power settings than I expected with both engines running; and 2. I was extra diligent taxing out to 1R because this is not our normal runway and it was night.fatigue/lack of alertness:I did not feel fatigued on this flight. I had 7 hours of sleep the previous night and I took a 1 hour nap on the afternoon prior to the event. However; this was the second red-eye I was performing in a 48 hour period and this was my forth night in a row where I was on duty past 3am EDT. This was my first month where I had accomplished only night flying (6 previous stand-ups) and may be a factor.unfortunately; I do not have specific suggestions for avoiding recurrence of this event (besides actually accomplishing the checklist items being acknowledged); because there were at least 2 places where my normal habit patterns broke down. However; I would like to acknowledge the training that I received that helped prepare me to handle the situation after it was recognized. Specifically this is training that I received in the oral portion of my check ride last winter were we discussed the greek 737 pressurization accident and a domestic incident where some people got hurt due to improper pressurization system management.

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Original NASA ASRS Text

Title: B737 Captain experienced cabin altitude warning horn passing 12;000 FT in the climb. Flight crew descended to 10;000 FT where the packs were discovered to be off and the outflow valve full open. After turning on the packs and switching to the alternate pressurization controller; pressurization returned to normal and the flight continued to the destination.

Narrative: Climbing out of 12;000 FT; the cabin altitude warning horn sounded. As I began to execute the CABIN ALTITUDE WARNING HORN immediate action items; I looked at the pressurization panel and noticed that both pack switches were in the off position. I discontinued the checklist after the first two steps; recognizing that the checklist would not resolve the problem. I directed the pilot flying to level the aircraft off at 12;000 FT; while I attained clearance to descend to 10;000 FT. Once clearance was received; I told the pilot flying that he had the aircraft and the radios; and I began trouble shooting the problem. During the descent; the aircraft began to exceed the programmed speed; so the auto throttles were turned off to keep the airspeed under control. I began executing the AUTO FAIL/UNSCHEDULED PRESSURIZATION CHANGE checklist. While running this checklist; we received an MASTER CAUTION/OFF SCHEDULED DESCENT indication. Resetting the MC system; I continued the AF/UPC checklist. Turning on the LEFT PACK switch to the ON position; I didn't observe any change to the pressurization system (outflow valve full open; DP needle at 0; cabin altitude 10;000 FT.) I switched the Pressurization Mode Selector Switch to manual; and manually closed the outflow valve in increments until the aircraft began to pressurize normally. Passing below an 8;000 foot cabin altitude; I moved the RIGHT PACK switch to the Auto position and moved the outflow valve the rest of the way to the full closed position. I had the Pilot Flying request a climb to 12;000 for extra terrain clearance and began to execute the OFF SCHEDULED DESCENT checklist. When that checklist was complete; I switched the Pressurization Mode Selector Switch to the ALTN position; once I could see it was pressurizing normal; I switched it to the AUTO position. Confirming that it was pressurizing normal; I resumed normal Pilot Not Flying duties; requested a normal climb out to cruise altitude. We reset the FLT ALT Indicator to normal cruise altitude and made sure all checklists were complete and closed.We; as a crew; missed a checklist item three times. Interruption/Distraction & High Workload/Task Saturation: The takeoff roll and initial climb was very bumpy and took a lot of crosswind control to maintain ground track. After take off; we had to turn to a 050 heading; change radio frequencies; execute the climb checklist; acknowledge and execute a change to our cleared altitude and way point; all in quick succession. Interruption/Distraction: A. I noticed the wind was howling as we entered the aircraft (the R1 door was open) and I was preoccupied that we either get turned into the wind or use the max motoring procedure for engine start. B. Two other minor issues preoccupied me on taxi out; 1. The aircraft required higher power settings than I expected with both engines running; and 2. I was extra diligent taxing out to 1R because this is not our normal runway and it was night.Fatigue/Lack of Alertness:I did not feel fatigued on this flight. I had 7 hours of sleep the previous night and I took a 1 hour nap on the afternoon prior to the event. However; this was the second red-eye I was performing in a 48 hour period and this was my forth night in a row where I was on duty past 3am EDT. This was my first month where I had accomplished only night flying (6 previous Stand-ups) and may be a factor.Unfortunately; I do not have specific suggestions for avoiding recurrence of this event (besides actually accomplishing the checklist items being acknowledged); because there were at least 2 places where my normal habit patterns broke down. However; I would like to acknowledge the training that I received that helped prepare me to handle the situation after it was recognized. Specifically this is training that I received in the oral portion of my check ride last winter were we discussed the Greek 737 pressurization accident and a domestic incident where some people got hurt due to improper pressurization system management.

Data retrieved from NASA's ASRS site as of April 2012 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.