Narrative:

We were departing ZZZ and had a last min captain change due to scheduling issues and we started off behind the time line. We pushed 14 mins late and were hustling to get things done. The WX in ZZZ was poor. The visibility was down due to fog and was right at minimums for takeoff. The tower could not see the ramp and issued a clearance around construction areas to runway xxr. We had planned for runway xxl. The ground controller also asked us to report several locations along our taxi route so that he could confirm our location. Other aircraft were also taxiing but could not be seen by the tower or us. The taxi was slow; with both pilots straining to see construction areas and airport signage and to follow the controller's directions. We were also making taxi position reports and looking for the other aircraft that we knew were out there. When we finally arrived at the end of runway xxr; we came up on another carrier. We were unaware of his presence during the taxi and were surprised to see him. We were given an immediate takeoff clearance; completed the checklist; and departed. At 10000 ft MSL; I called for the climb checklist. Almost simultaneously; we got the cabin altitude warning horn. Both pilots immediately performed the boxed procedures. Simultaneously; I leveled off (about 11000 ft MSL) and noted the cabin altitude was at 10000 ft. We immediately asked for and received a clearance down to 10000 ft and then got a subsequent clearance down to 9000 ft MSL. We asked for a vector to work the issue. The captain ran the checklist and immediately noticed that the engine bleed switches were off. He turned them on in accordance with the checklist and the aircraft pressurized normally. The masks in the back did not drop and the cabin altitude did not go much above 10000 ft. We briefed the flight attendants that everything was back to normal and told ATC the same. We continued on our route of flight at planned cruise altitude. The remainder of the flight was uneventful. This situation was avoidable. We were dealing with several distrs during the morning that should have not left bleed switches 'off' the night before and gone unnoticed. We are so accustomed to them always being 'on' that it was mistakenly overlooked. The captain change; being late; the runway change after push; the low visibility taxi; position reporting; and other aircraft that we could not see; all were very distracting and led us to miss this item on the before takeoff checklist. We were so focused on the taxi concerns and external threats that the checklist was not properly run. Simply put; strict checklist discipline would have prevented this issue. We clearly needed to slow things down even more to ensure that everything was set properly. Another factor was that the bleed switches were left off. After literally hundreds of aircraft startups; I have never seen this issue. I have never had to turn on the engine bleeds when preflting before. Again; preflight discipline would have caught this. Nothing can be taken for granted. When distrs are pulling you away from normal habit patterns and procedures -- stop! Slow down and make things right!

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Original NASA ASRS Text

Title: B737-700 FAILS TO PRESSURIZE WHEN FLIGHT CREW DOES NOT NOTE ENGINE BLEEDS WERE CLOSED.

Narrative: WE WERE DEPARTING ZZZ AND HAD A LAST MIN CAPT CHANGE DUE TO SCHEDULING ISSUES AND WE STARTED OFF BEHIND THE TIME LINE. WE PUSHED 14 MINS LATE AND WERE HUSTLING TO GET THINGS DONE. THE WX IN ZZZ WAS POOR. THE VISIBILITY WAS DOWN DUE TO FOG AND WAS RIGHT AT MINIMUMS FOR TKOF. THE TWR COULD NOT SEE THE RAMP AND ISSUED A CLRNC AROUND CONSTRUCTION AREAS TO RWY XXR. WE HAD PLANNED FOR RWY XXL. THE GND CTLR ALSO ASKED US TO RPT SEVERAL LOCATIONS ALONG OUR TAXI RTE SO THAT HE COULD CONFIRM OUR LOCATION. OTHER ACFT WERE ALSO TAXIING BUT COULD NOT BE SEEN BY THE TWR OR US. THE TAXI WAS SLOW; WITH BOTH PLTS STRAINING TO SEE CONSTRUCTION AREAS AND ARPT SIGNAGE AND TO FOLLOW THE CTLR'S DIRECTIONS. WE WERE ALSO MAKING TAXI POSITION RPTS AND LOOKING FOR THE OTHER ACFT THAT WE KNEW WERE OUT THERE. WHEN WE FINALLY ARRIVED AT THE END OF RWY XXR; WE CAME UP ON ANOTHER CARRIER. WE WERE UNAWARE OF HIS PRESENCE DURING THE TAXI AND WERE SURPRISED TO SEE HIM. WE WERE GIVEN AN IMMEDIATE TKOF CLRNC; COMPLETED THE CHKLIST; AND DEPARTED. AT 10000 FT MSL; I CALLED FOR THE CLB CHKLIST. ALMOST SIMULTANEOUSLY; WE GOT THE CABIN ALT WARNING HORN. BOTH PLTS IMMEDIATELY PERFORMED THE BOXED PROCS. SIMULTANEOUSLY; I LEVELED OFF (ABOUT 11000 FT MSL) AND NOTED THE CABIN ALT WAS AT 10000 FT. WE IMMEDIATELY ASKED FOR AND RECEIVED A CLRNC DOWN TO 10000 FT AND THEN GOT A SUBSEQUENT CLRNC DOWN TO 9000 FT MSL. WE ASKED FOR A VECTOR TO WORK THE ISSUE. THE CAPT RAN THE CHKLIST AND IMMEDIATELY NOTICED THAT THE ENG BLEED SWITCHES WERE OFF. HE TURNED THEM ON IN ACCORDANCE WITH THE CHKLIST AND THE ACFT PRESSURIZED NORMALLY. THE MASKS IN THE BACK DID NOT DROP AND THE CABIN ALT DID NOT GO MUCH ABOVE 10000 FT. WE BRIEFED THE FLT ATTENDANTS THAT EVERYTHING WAS BACK TO NORMAL AND TOLD ATC THE SAME. WE CONTINUED ON OUR RTE OF FLT AT PLANNED CRUISE ALT. THE REMAINDER OF THE FLT WAS UNEVENTFUL. THIS SITUATION WAS AVOIDABLE. WE WERE DEALING WITH SEVERAL DISTRS DURING THE MORNING THAT SHOULD HAVE NOT LEFT BLEED SWITCHES 'OFF' THE NIGHT BEFORE AND GONE UNNOTICED. WE ARE SO ACCUSTOMED TO THEM ALWAYS BEING 'ON' THAT IT WAS MISTAKENLY OVERLOOKED. THE CAPT CHANGE; BEING LATE; THE RWY CHANGE AFTER PUSH; THE LOW VISIBILITY TAXI; POSITION RPTING; AND OTHER ACFT THAT WE COULD NOT SEE; ALL WERE VERY DISTRACTING AND LED US TO MISS THIS ITEM ON THE BEFORE TKOF CHKLIST. WE WERE SO FOCUSED ON THE TAXI CONCERNS AND EXTERNAL THREATS THAT THE CHKLIST WAS NOT PROPERLY RUN. SIMPLY PUT; STRICT CHKLIST DISCIPLINE WOULD HAVE PREVENTED THIS ISSUE. WE CLEARLY NEEDED TO SLOW THINGS DOWN EVEN MORE TO ENSURE THAT EVERYTHING WAS SET PROPERLY. ANOTHER FACTOR WAS THAT THE BLEED SWITCHES WERE LEFT OFF. AFTER LITERALLY HUNDREDS OF ACFT STARTUPS; I HAVE NEVER SEEN THIS ISSUE. I HAVE NEVER HAD TO TURN ON THE ENG BLEEDS WHEN PREFLTING BEFORE. AGAIN; PREFLT DISCIPLINE WOULD HAVE CAUGHT THIS. NOTHING CAN BE TAKEN FOR GRANTED. WHEN DISTRS ARE PULLING YOU AWAY FROM NORMAL HABIT PATTERNS AND PROCS -- STOP! SLOW DOWN AND MAKE THINGS RIGHT!

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