Narrative:

We departed lga flying the coney departure. All pre-departure checklist items had been completely briefed. Because of weight restrictions on runway 13, the takeoff required a flaps 1 setting with engine bleeds off. This confign is normal, however, not common. I was the PF. During the initial stages of the climb out, I called for, and the captain completed, the after takeoff checklist, which is a silent checklist. While he was completing the checklist, we received several ATC instructions including radio, altitude, and heading changes. We also entered icing conditions requiring the anti-icing system. All of these things interrupted the flow of the checklist. As a result, the captain inadvertently shut down the APU without first turning the aircraft engine bleed switches to 'on.' this resulted in a gradual rise in the aircraft cabin altitude. Since we had a gradual rise in cabin altitude and a rapid climb rate, the 10000 ft warning horn did not sound until we passed 11000 ft. By the time we figure out we had a pressurization problem, received clearance and began the pushover from a climb to a descent, the aircraft passed through 14000 ft and the passenger oxygen masks automatically deployed. We requested and received clearance to return to lga where an uneventful landing was made. I believe this situation occurred as a result of several conditions. First, the new emphasis being placed on strict adherence to checklist items. Secondly, the checklist is run silently, which leaves the PF out of the loop. Finally, the congestion in the ny area causes frequent breaks in the flow of the checklist during critical phases of flight.

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Original NASA ASRS Text

Title: ACR MLG FAILED TO PRESSURIZE.

Narrative: WE DEPARTED LGA FLYING THE CONEY DEP. ALL PRE-DEP CHKLIST ITEMS HAD BEEN COMPLETELY BRIEFED. BECAUSE OF WT RESTRICTIONS ON RWY 13, THE TKOF REQUIRED A FLAPS 1 SETTING WITH ENG BLEEDS OFF. THIS CONFIGN IS NORMAL, HOWEVER, NOT COMMON. I WAS THE PF. DURING THE INITIAL STAGES OF THE CLBOUT, I CALLED FOR, AND THE CAPT COMPLETED, THE AFTER TKOF CHKLIST, WHICH IS A SILENT CHKLIST. WHILE HE WAS COMPLETING THE CHKLIST, WE RECEIVED SEVERAL ATC INSTRUCTIONS INCLUDING RADIO, ALT, AND HDG CHANGES. WE ALSO ENTERED ICING CONDITIONS REQUIRING THE ANTI-ICING SYS. ALL OF THESE THINGS INTERRUPTED THE FLOW OF THE CHKLIST. AS A RESULT, THE CAPT INADVERTENTLY SHUT DOWN THE APU WITHOUT FIRST TURNING THE ACFT ENG BLEED SWITCHES TO 'ON.' THIS RESULTED IN A GRADUAL RISE IN THE ACFT CABIN ALT. SINCE WE HAD A GRADUAL RISE IN CABIN ALT AND A RAPID CLB RATE, THE 10000 FT WARNING HORN DID NOT SOUND UNTIL WE PASSED 11000 FT. BY THE TIME WE FIGURE OUT WE HAD A PRESSURIZATION PROB, RECEIVED CLRNC AND BEGAN THE PUSHOVER FROM A CLB TO A DSCNT, THE ACFT PASSED THROUGH 14000 FT AND THE PAX OXYGEN MASKS AUTOMATICALLY DEPLOYED. WE REQUESTED AND RECEIVED CLRNC TO RETURN TO LGA WHERE AN UNEVENTFUL LNDG WAS MADE. I BELIEVE THIS SIT OCCURRED AS A RESULT OF SEVERAL CONDITIONS. FIRST, THE NEW EMPHASIS BEING PLACED ON STRICT ADHERENCE TO CHKLIST ITEMS. SECONDLY, THE CHKLIST IS RUN SILENTLY, WHICH LEAVES THE PF OUT OF THE LOOP. FINALLY, THE CONGESTION IN THE NY AREA CAUSES FREQUENT BREAKS IN THE FLOW OF THE CHKLIST DURING CRITICAL PHASES OF FLT.

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.