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B737-400 suffered loss of auto pressurization control.
| Attributes | |
| ACN | 847179 |
| Time | |
| Date | 200908 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | ZDC.ARTCC |
| State Reference | VA |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B737-400 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Climb |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Pressurization Control System |
| Person 1 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
Climbing through fl 250; cabin altitude warning horn sounded. We donned oxygen masks and followed QRH procedure for warning horn - cabin altitude. Also placed both pack switches to high; but no success. Per QRH; we accomplished the excessive cabin altitude checklist; and regained control of the pressurization when we switched to manual AC mode. Cabin altitude was climbing at approximately 500 fpm during this time; and stopped at approximately 12000 feet when we regained control. Cabin altitude descent was approximately 2000 fpm; and was rather abrupt to the flight attendants and passengers. No auto fail light; nor did the controller automatically switch to standby. We requested a level off at FL250 with ATC at the start of this event; and stayed there during this time while we considered if we wanted to continue on the filed overwater route. We contacted the dispatcher; who contacted maintenance; who suggested we try the standby mode. Standby worked fine and we decided to continue but refile our route over land. We continued to destination without further incident. This was a repeat event from several days ago; and maintenance had just removed the MEL prior to this flight. Don't know details of what maintenance actions were accomplished to clear the MEL.
Original NASA ASRS Text
Title: B737-400 suffered loss of auto pressurization control.
Narrative: Climbing through FL 250; cabin altitude warning horn sounded. We donned oxygen masks and followed QRH procedure for Warning Horn - Cabin Altitude. Also placed both pack switches to High; but no success. Per QRH; we accomplished the Excessive Cabin Altitude checklist; and regained control of the pressurization when we switched to Manual AC mode. Cabin altitude was climbing at approximately 500 fpm during this time; and stopped at approximately 12000 feet when we regained control. Cabin altitude descent was approximately 2000 fpm; and was rather abrupt to the Flight Attendants and passengers. No Auto Fail light; nor did the controller automatically switch to standby. We requested a level off at FL250 with ATC at the start of this event; and stayed there during this time while we considered if we wanted to continue on the filed overwater route. We contacted the Dispatcher; who contacted Maintenance; who suggested we try the standby mode. Standby worked fine and we decided to continue but refile our route over land. We continued to destination without further incident. This was a repeat event from several days ago; and maintenance had just removed the MEL prior to this flight. Don't know details of what maintenance actions were accomplished to clear the MEL.
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.