A B737-800 flight crew reported taking off with the Bleed Air Switches CLOSED and above 10;000 FT the cabin altitude warning horn sounded. An emergency declaration was canceled and the flight continued to its destination after the bleed switches were OPENED.
Synopsis
A B737-800 flight crew reported taking off with the Bleed Air Switches CLOSED and above 10;000 FT the cabin altitude warning horn sounded. An emergency declaration was canceled and the flight continued to its destination after the bleed switches were OPENED.
Narrative
Around 10;000 FT on the climbout; the #1 Flight Attendant called to tell us that the cabin was warm; there was an exhaust smell and his ears were popping. A few seconds later we got a cabin altitude warning horn. The Captain was the first to put on his mask. I stopped the climbing and then donned mine. I was very busy trying to maneuver the aircraft smoothly with the autopilot off and did not immediately establish communications. The Captain advised ATC that we had a pressurization problem and needed to descend. I turned the Pressurization Mode Control switch to MAN and turned the valve switched to CLOSED. Next I set up the flight intercom and advised the Captain of my actions. We requested 8;000 FT and a return. When everything was stable; the Captain noticed the Engine Bleed switches were in the OFF position. We turned the switches ON and Pressurization Mode Controller to AUTO. The aircraft began to pressurize normally. We discussed the fuel status and determined that; from a safety standpoint; there was no obstacles in continuing. We advised ATC of our status and requested on course. We were then cleared en route and continued the flight with no further interruptions. From my perspective; contributing factors in this event were a poor nights sleep and a last minute change of power from standard thrust to 22;000 maximum due to a tailwind component of about 1 knot. I think if I didn't have that power change on my mind I may have noticed the different feel of the pressurization on takeoff. The #1 Flight Attendant was sharp to notify us of the unusual temperature and smell in the cabin. I don't know at what point the engine bleed valves were switched to off or if they were never switched on. The fact that I didn't catch them with the checklist is troubling and will require a good deal of thought and much more vigilance in order to avoid similar problems in the future. It may be worth mentioning that the Cabin Altitude Warning horn went off until the cabin came back to below 10;000 FT. We train to silence the bell when we get a fire warning but it isn't usually discussed for a Cabin Altitude Warning. It didn't occur to me to silence it until it was too late but would have been helpful.
Second reporter narrative
Clearance received at gate by voice due to re-route. Checklists completed and taxi clearance as expected to hold short of Runway 23. Received clearance to 'line up and wait.' Just as I was setting parking brake on runway; First Officer observes slight tailwind. Switching to max 22 KT for tailwind; Tower clears for takeoff. Finishing up getting numbers in place for V speeds; Tower advises they need an immediate roll. Normal takeoff followed. Initial climbout normal; nothing noticed by both pilots. Cabin Altitude Alert warning comes on; so we perform our immediate action items; and with masks on; First Officer smoothly leveled at no more than 12.5 and descended back to 10;000 with Pressurization set to Manual; Outflow Valve to CLOSED did not help. All door lights still out; not having any idea why; I could not keep air in the airplane. I declared an emergency and requested a return. At my request we were given a turning descent to 8;000. I assigned all flying and communicating duties to First Officer so I could talk with Flight Attendants and make PA's. Once done; reaching for QRH; I just sat back and tried to see what was being missed in the 'big picture.' Now reading every switch position on the air and bleed panels; I first noted that the engine bleeds were in the OFF position. Switches were returned to on and all systems returned to normal. Discussed all items with First Officer on resolution; checked fuel for destination; with consideration to weather. We agreed that continuing to our destination was a safe course of action. I felt it necessary to bring Flight Attendants in on this decision; to assure their comfort with this decision and get their opinion on the passengers current condition/reaction to the events. They felt passengers were calm and would be ok. PA was made to assure passengers of aircraft condition. I did acknowledge their concerns. Called Flight Attendants again; and they said all reactions were positive and passengers were happy to be continuing. Informed ATC and they cleared us on route with no further issues. Flight continued without incident. Arrival about 5 minutes behind schedule; but saved nearly 2;000 LBS of fuel. I would like to commend the alertness of my #1 Flight Attendant and willingness to contact the cockpit as soon as he felt something was not right. His long history as a Flight Attendant really shows his knowledge and abilities. He is someone I would like to stay with the Company. Factors for this occurrence for me were as follows: 1) the VERY early departure body clock time. I'm not a morning person. 2) I have about 400 hours on the aircraft all being in the left seat. Having not ever operated as a First Officer in the 737; the air panels are foreign to my hands. When asked in 3 checklists about the packs and bleeds; I looked over every time and saw switches in the 'UP' position; and 'UP' to me is still 'ON.' This is my error. I will read switches next time. Altitude Cutout Horn continued to sound the entire time above 10;000 FT. All training about altitude and cabin at no time were we presented with a situation to press the Cabin Altitude Warning horn cutout. That was a distraction; as one could imagine. I know it is my job to catch the one item that precipitated this situation. Something that may assist prevention of this might be for the maintenance checklists to align with ours so that when they leave they are not shutting off switches we expect to remain in the 'ON' position.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.