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A B737-300 crew reported that the cabin altitude warning horn came on, indicating a cabin altitude above 10000 ft. The crew delayed an emergency descent until they had clearance from ZOA radar controller.
| Attributes | |
| ACN | 594686 |
| Time | |
| Date | 200309 |
| Day | Sun |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| State Reference | CA |
| Altitude | msl single value : 33000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zoa.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Experience | flight time last 90 days : 240 flight time total : 15000 flight time type : 10000 |
| ASRS Report | 594686 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Experience | flight time last 90 days : 250 flight time total : 7500 flight time type : 3200 |
| ASRS Report | 594687 |
| Events | |
| Anomaly | aircraft equipment problem : critical non adherence : published procedure non adherence : company policies other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : cabin alt warning horn other flight crewa other flight crewb |
| Resolutory Action | controller : issued new clearance |
| Consequence | other other |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance Aircraft |
| Primary Problem | Aircraft |
Narrative:
After 10 mins of cruise at FL330, the cabin warning horn came on. We requested an immediate descent. There was some confusion with the controller. He thought we were already descending, but we remained level until cleared to descend. Further confusion resulted because both xponders were intermittent. Later conversation with ZOA and company ATC specialist indicated that there was no problem but that an as soon as possible report should be filed. At all times ZOA was very helpful in responding to this emergency as well as several other electrical problems we were working.
Original NASA ASRS Text
Title: A B737-300 CREW RPTED THAT THE CABIN ALT WARNING HORN CAME ON, INDICATING A CABIN ALT ABOVE 10000 FT. THE CREW DELAYED AN EMER DSCNT UNTIL THEY HAD CLRNC FROM ZOA RADAR CTLR.
Narrative: AFTER 10 MINS OF CRUISE AT FL330, THE CABIN WARNING HORN CAME ON. WE REQUESTED AN IMMEDIATE DSCNT. THERE WAS SOME CONFUSION WITH THE CTLR. HE THOUGHT WE WERE ALREADY DSNDING, BUT WE REMAINED LEVEL UNTIL CLRED TO DSND. FURTHER CONFUSION RESULTED BECAUSE BOTH XPONDERS WERE INTERMITTENT. LATER CONVERSATION WITH ZOA AND COMPANY ATC SPECIALIST INDICATED THAT THERE WAS NO PROB BUT THAT AN ASAP RPT SHOULD BE FILED. AT ALL TIMES ZOA WAS VERY HELPFUL IN RESPONDING TO THIS EMER AS WELL AS SEVERAL OTHER ELECTRICAL PROBS WE WERE WORKING.
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.