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A B737 crew, climbing through 10000 ft, experienced the cabin attendant altitude warning horn. The result of leaving the press switch in the manual position.
| Attributes | |
| ACN | 531653 |
| Time | |
| Date | 200112 |
| Day | Sun |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : abq.airport |
| State Reference | NM |
| Altitude | msl single value : 14500 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : abq.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | climbout : intermediate altitude |
| Route In Use | departure : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : multi engine pilot : private pilot : instrument |
| Experience | flight time last 90 days : 156 flight time total : 4100 flight time type : 317 |
| ASRS Report | 531653 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Events | |
| Anomaly | aircraft equipment problem : critical non adherence : company policies non adherence : published procedure non adherence other |
| Independent Detector | aircraft equipment other aircraft equipment : cab alt warning horn other flight crewa other flight crewb |
| Resolutory Action | controller : provided flight assist flight crew : overcame equipment problem flight crew : diverted to another airport flight crew : declared emergency |
| Consequence | other |
| Supplementary | |
| Problem Areas | Aircraft Flight Crew Human Performance |
| Primary Problem | Flight Crew Human Performance |
Narrative:
On departure from abq, a warning horn began to sound shortly after the flaps were raised. After passing 10000 ft I looked up and glanced at the cabin attendant temperature and pressure. The climb rate was high, about 2000 FPM, and cabin attendant altitude was high. I am not sure how high, maybe 9000 ft. I was flying. I looked at the pack switches and engine bleed switches. They were in automatic and on. I was given a vector and concentrated on flying the aircraft. I thought, if the aircraft is depressurizing, what lights will come on? The auxiliary oxygen system on light. Too late, the light was on. We were around 14500 ft. A descent was begun. I made a call to the passenger with my oxygen mask on. At the end of the announcement, I noticed the microphone switch was still in boom. We were now turning base and running checklists. On final I found the pressure switch in manual. My flow must have been interrupted during the pressure check and I did not return to it. I did not even consider the pressure switch since I 'checked it' during my flow. The landing was uneventful. During an unusual situation, regardless of what you're sure you checked, check it again. When interrupted during your flow, start over from the beginning. When any warning horn comes on during departure, level off immediately, if able, and then do the troubleshooting.
Original NASA ASRS Text
Title: A B737 CREW, CLBING THROUGH 10000 FT, EXPERIENCED THE CAB ALT WARNING HORN. THE RESULT OF LEAVING THE PRESS SWITCH IN THE MANUAL POS.
Narrative: ON DEP FROM ABQ, A WARNING HORN BEGAN TO SOUND SHORTLY AFTER THE FLAPS WERE RAISED. AFTER PASSING 10000 FT I LOOKED UP AND GLANCED AT THE CAB TEMP AND PRESSURE. THE CLB RATE WAS HIGH, ABOUT 2000 FPM, AND CAB ALT WAS HIGH. I AM NOT SURE HOW HIGH, MAYBE 9000 FT. I WAS FLYING. I LOOKED AT THE PACK SWITCHES AND ENG BLEED SWITCHES. THEY WERE IN AUTO AND ON. I WAS GIVEN A VECTOR AND CONCENTRATED ON FLYING THE ACFT. I THOUGHT, IF THE ACFT IS DEPRESSURIZING, WHAT LIGHTS WILL COME ON? THE AUX OXYGEN SYS ON LIGHT. TOO LATE, THE LIGHT WAS ON. WE WERE AROUND 14500 FT. A DSCNT WAS BEGUN. I MADE A CALL TO THE PAX WITH MY OXYGEN MASK ON. AT THE END OF THE ANNOUNCEMENT, I NOTICED THE MIC SWITCH WAS STILL IN BOOM. WE WERE NOW TURNING BASE AND RUNNING CHECKLISTS. ON FINAL I FOUND THE PRESSURE SWITCH IN MANUAL. MY FLOW MUST HAVE BEEN INTERRUPTED DURING THE PRESSURE CHECK AND I DID NOT RETURN TO IT. I DID NOT EVEN CONSIDER THE PRESSURE SWITCH SINCE I 'CHECKED IT' DURING MY FLOW. THE LNDG WAS UNEVENTFUL. DURING AN UNUSUAL SIT, REGARDLESS OF WHAT YOU'RE SURE YOU CHECKED, CHECK IT AGAIN. WHEN INTERRUPTED DURING YOUR FLOW, START OVER FROM THE BEGINNING. WHEN ANY WARNING HORN COMES ON DURING DEP, LEVEL OFF IMMEDIATELY, IF ABLE, AND THEN DO THE TROUBLESHOOTING.
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.