When the flight crew of a B737-800 failed to note both pack switches were off prior to takeoff they ...

Attributes
ACN	988193
Time
Date	201201
Local Time Of Day	0601-1200
Place
Locale Reference	ORD.Airport
State Reference	IL
Aircraft 1
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Initial Climb
Flight Plan	IFR
Component
Aircraft Component	Pressurization System
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy

Narrative:

During climb; the cabin altitude warning horn activated passing approximately; 11;000 ft. First officer (pilot flying) immediately donned O2 mask and leveled aircraft at 11;000 ft (with ATC permission). We quickly recognized that our problem was that both packs were off. 'Cabin altitude warning' procedures were stopped and one pack was reinstated. After pressurization stabilized; the second pack was reinstated and normal operations resumed. The remainder of flight was uneventful. The aircraft had overnighted in ord. I believe the pack switches may have been off when we arrived at the aircraft. A contributing factor to the crew's missing the incorrect position of the pack switches was the mild outside temperature and neither heating nor cooling were required before takeoff.

Original NASA ASRS Text

Title: When the flight crew of a B737-800 failed to note both pack switches were off prior to takeoff they predictably received a Cabin Altitude Warning during the climb. They leveled off; turned the packs back on one at a time; and continued the flight.

Narrative: During climb; the cabin altitude warning horn activated passing approximately; 11;000 FT. First Officer (pilot flying) immediately donned O2 mask and leveled aircraft at 11;000 FT (with ATC permission). We quickly recognized that our problem was that both packs were off. 'Cabin Altitude Warning' procedures were stopped and one pack was reinstated. After pressurization stabilized; the second pack was reinstated and normal operations resumed. The remainder of flight was uneventful. The aircraft had overnighted in ORD. I believe the pack switches may have been off when we arrived at the aircraft. A contributing factor to the crew's missing the incorrect position of the pack switches was the mild outside temperature and neither heating nor cooling were required before takeoff.

Data retrieved from NASA's ASRS site as of July 2013 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.

When the flight crew of a B737-800 failed to note both pack switches were off prior to takeoff they predictably received a cabin altitude warning during the climb. They leveled off; turned the packs back on one at a time; and continued the flight.