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B737-400 flight crew experiences cabin altitude warning at FL340 in an aircraft that has a history of previous problems. Crew descends to FL200 where pressurization can be maintained with the out flow valve closed; and elects to return to departure airport.
| Attributes | |
| ACN | 834153 |
| Time | |
| Date | 200905 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B737-400 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Pressurization System |
| Person 1 | |
| Function | Captain Pilot Flying |
| Person 2 | |
| Function | First Officer Pilot Not Flying |
| Experience | Flight Crew Last 90 Days 100 |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
Depressurization at 34;000 ft. Noted previous write up associated with same issue in prior days. Climb uneventful. Pressurization checked going through 10;000 ft. Pressurization checked at level off at 34;000 ft. Cabin altitude showing approximately 8;000. 5 minutes later approximately intermittent warning horn sounded. Memory items; QRH accomplished. Standby pressurization selected; noted outflow valve closed. Emergency declared with decent initiated towards 28;000 ft. Cabin altitude noted at FL280 was 11;000 ft. Continued decent towards FL240. Cabin altitude noted was 10;500 ft. Continued decent towards FL200. Cabin altitude noted was now acceptable at 8;500 ft. Outflow valve still noted closed as was during the entire decent. Stopped decent at 20;000 ft; reviewed checklists run; checked fuel and weather and contacted dispatch. Dispatch advised a return to ZZZ. Rest of flight at FL200 until decent to ZZZ uneventful with operation dealing with pressurization normal at FL200. Canceled the emergency at FL200 when pressure stabilized.
Original NASA ASRS Text
Title: B737-400 flight crew experiences cabin altitude warning at FL340 in an aircraft that has a history of previous problems. Crew descends to FL200 where pressurization can be maintained with the out flow valve closed; and elects to return to departure airport.
Narrative: Depressurization at 34;000 FT. Noted previous write up associated with same issue in prior days. Climb uneventful. Pressurization checked going through 10;000 FT. Pressurization checked at level off at 34;000 FT. Cabin altitude showing approximately 8;000. 5 minutes later approximately intermittent warning horn sounded. Memory items; QRH accomplished. Standby pressurization selected; noted outflow valve closed. Emergency declared with decent initiated towards 28;000 FT. Cabin altitude noted at FL280 was 11;000 FT. Continued decent towards FL240. Cabin altitude noted was 10;500 FT. Continued decent towards FL200. Cabin altitude noted was now acceptable at 8;500 FT. Outflow valve still noted closed as was during the entire decent. Stopped decent at 20;000 FT; reviewed checklists run; checked fuel and weather and contacted Dispatch. Dispatch advised a return to ZZZ. Rest of flight at FL200 until decent to ZZZ uneventful with operation dealing with pressurization normal at FL200. Canceled the emergency at FL200 when pressure stabilized.
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.