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Flight crew of an large transport air carrier aircraft made an emergency descent until correcting a pressurization problem and then returned to original assigned altitude.
| Attributes | |
| ACN | 256443 |
| Time | |
| Date | 199311 |
| Day | Sat |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : mkc |
| State Reference | MO |
| Altitude | msl bound lower : 36000 msl bound upper : 36000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zkc tower : yul |
| Operator | common carrier : air carrier |
| Make Model Name | Large Transport, Low Wing, 3 Turbojet Eng |
| Flight Phase | climbout : intermediate altitude 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 : 250 flight time total : 10000 flight time type : 2500 |
| ASRS Report | 256443 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 176 flight time total : 5640 flight time type : 1700 |
| ASRS Report | 256444 |
| Events | |
| Anomaly | aircraft equipment problem : critical other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | flight crew : overcame equipment problem flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
In climb FL360 for 370, aural cabin warning sounded. Instruments indicated cabin at 10000 ft and climbing at 400 FPM. Switched pressurization to standby, checked outflow valve closed and initiated a descent after coordinating with ATC. Early during descent to 10000 ft, investigation revealed the left pack switch was off. Switch was turned on and pressurization returned to normal. Returned system to automatic and continued to mci. We suspect that, during transition through FL310 in climb, the pack switch was inadvertently turned off.
Original NASA ASRS Text
Title: FLC OF AN LGT ACR ACFT MADE AN EMER DSCNT UNTIL CORRECTING A PRESSURIZATION PROB AND THEN RETURNED TO ORIGINAL ASSIGNED ALT.
Narrative: IN CLB FL360 FOR 370, AURAL CABIN WARNING SOUNDED. INSTS INDICATED CABIN AT 10000 FT AND CLBING AT 400 FPM. SWITCHED PRESSURIZATION TO STANDBY, CHKED OUTFLOW VALVE CLOSED AND INITIATED A DSCNT AFTER COORDINATING WITH ATC. EARLY DURING DSCNT TO 10000 FT, INVESTIGATION REVEALED THE L PACK SWITCH WAS OFF. SWITCH WAS TURNED ON AND PRESSURIZATION RETURNED TO NORMAL. RETURNED SYS TO AUTO AND CONTINUED TO MCI. WE SUSPECT THAT, DURING TRANSITION THROUGH FL310 IN CLB, THE PACK SWITCH WAS INADVERTENTLY TURNED OFF.
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.