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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Air carrier has cabin pressure climb at beginning of descent. Emergency descent made after response to TCASII.
| Attributes | |
| ACN | 203636 |
| Time | |
| Date | 199203 |
| Day | Tue |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : sps |
| State Reference | TX |
| Altitude | msl bound lower : 10000 msl bound upper : 37000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zfw |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | cruise other descent other other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 10000 flight time type : 8000 |
| ASRS Report | 203636 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 4600 flight time type : 750 |
| ASRS Report | 204276 |
| Events | |
| Anomaly | aircraft equipment problem : critical altitude deviation : excursion from assigned altitude other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : declared emergency other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | Pilot Deviation |
Narrative:
FL370 with discretion to FL240 cabin pressure started climbing at maximum rate for no reason. Put mask on and started descent while first officer tried to close outflow valve. I made a mistake and failed to FLIP my microphone mask switch to mask, and was unable to communication with fort worth. Thinking I may have a second problem (radios) I squawked 7700, then waited for an airplane to clear on TCASII (15-30 seconds), then continued the descent, finally realizing my mistake and flipping the switch to communication with fort worth ARTCC. Leveled at 10000 ft and once flight attendants reported all ok, cancelled emergency. Recommendations: I admitted my mistake to company so they could emphasize the mask switch to others. Procedure now says 'establish communication' which I thought I had done rather profoundly when I screamed close the outflow valve at the first officer just as I put my mask on. My new procedure is FLIP the switch and establish communication. Supplemental information from acn 204276: due to high workload, the approach descent checklist was completed at 10000 ft and not 18000 ft, and the final descent checklist was completed at approximately 700 ft AGL before landing. Never saw cabin above 16000 ft.
Original NASA ASRS Text
Title: ACR HAS CABIN PRESSURE CLB AT BEGINNING OF DSCNT. EMER DSCNT MADE AFTER RESPONSE TO TCASII.
Narrative: FL370 WITH DISCRETION TO FL240 CABIN PRESSURE STARTED CLBING AT MAX RATE FOR NO REASON. PUT MASK ON AND STARTED DSCNT WHILE FO TRIED TO CLOSE OUTFLOW VALVE. I MADE A MISTAKE AND FAILED TO FLIP MY MICROPHONE MASK SWITCH TO MASK, AND WAS UNABLE TO COM WITH FORT WORTH. THINKING I MAY HAVE A SECOND PROBLEM (RADIOS) I SQUAWKED 7700, THEN WAITED FOR AN AIRPLANE TO CLR ON TCASII (15-30 SECONDS), THEN CONTINUED THE DSCNT, FINALLY REALIZING MY MISTAKE AND FLIPPING THE SWITCH TO COM WITH FORT WORTH ARTCC. LEVELED AT 10000 FT AND ONCE FLT ATTENDANTS RPTED ALL OK, CANCELLED EMER. RECOMMENDATIONS: I ADMITTED MY MISTAKE TO COMPANY SO THEY COULD EMPHASIZE THE MASK SWITCH TO OTHERS. PROC NOW SAYS 'ESTABLISH COM' WHICH I THOUGHT I HAD DONE RATHER PROFOUNDLY WHEN I SCREAMED CLOSE THE OUTFLOW VALVE AT THE FO JUST AS I PUT MY MASK ON. MY NEW PROC IS FLIP THE SWITCH AND ESTABLISH COM. SUPPLEMENTAL INFO FROM ACN 204276: DUE TO HIGH WORKLOAD, THE APCH DSCNT CHKLIST WAS COMPLETED AT 10000 FT AND NOT 18000 FT, AND THE FINAL DSCNT CHKLIST WAS COMPLETED AT APPROX 700 FT AGL BEFORE LNDG. NEVER SAW CABIN ABOVE 16000 FT.
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.