Large transport aircraft had rapid cabin pressure uncontrolled, cabin altitude rose to approximately 15,000'. Emergency descent to 10,000'.

Home

Browse by month

Random

Latest

About

Contact

Attributes
ACN	130178
Time
Date	198912
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : adm airport : tul
State Reference	OK
Altitude	msl bound lower : 10000 msl bound upper : 35000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zfw
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : flight engineer pilot : instrument pilot : atp
Experience	flight time last 90 days : 180 flight time total : 7000 flight time type : 3000
ASRS Report	130178
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 8000 flight time type : 2500
ASRS Report	130179
Events
Anomaly	aircraft equipment problem : critical altitude deviation : undershoot
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance flight crew : overcame equipment problem other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

In cruise 35,000' cabin started sudden 2000+ FPM climb. Lower altitude was requested, received. Cabin altitude exceeded 10,000' in less than 30 second. Emergency was declared and descent was made to 10,000'. Explosive decompression and emergency descent checklists were executed. In the course of completing the rapid depressurization procedure the F/east found the outflow valve indicating almost full open (electronic pressurization system). He closed it using manual-electric. I don't know how high the cabin got, but I suspect it didn't get any higher than about 15,000'. 98 people on board, no apparent injuries - crew or passenger. Main question is why the outflow valve would suddenly go full open. As an aside, I rather forcefully told the F/east to go for manual 'based on my long (too long) experience as a F/east on various aircraft.' if he had done this first, I think we could have stopped the cabin climb in this situation. Maybe a wrong response on this aircraft, though as our checklist says to start at the top of the panel and work down. Manual and valve position is the last item to check - why?

Original NASA ASRS Text

Title: LGT ACFT HAD RAPID CABIN PRESSURE UNCONTROLLED, CABIN ALT ROSE TO APPROXIMATELY 15,000'. EMERGENCY DESCENT TO 10,000'.

Narrative: IN CRUISE 35,000' CABIN STARTED SUDDEN 2000+ FPM CLIMB. LOWER ALT WAS REQUESTED, RECEIVED. CABIN ALT EXCEEDED 10,000' IN LESS THAN 30 SEC. EMER WAS DECLARED AND DSCNT WAS MADE TO 10,000'. EXPLOSIVE DECOMPRESSION AND EMER DSCNT CHECKLISTS WERE EXECUTED. IN THE COURSE OF COMPLETING THE RAPID DEPRESSURIZATION PROC THE F/E FOUND THE OUTFLOW VALVE INDICATING ALMOST FULL OPEN (ELECTRONIC PRESSURIZATION SYSTEM). HE CLOSED IT USING MANUAL-ELECTRIC. I DON'T KNOW HOW HIGH THE CABIN GOT, BUT I SUSPECT IT DIDN'T GET ANY HIGHER THAN ABOUT 15,000'. 98 PEOPLE ON BOARD, NO APPARENT INJURIES - CREW OR PAX. MAIN QUESTION IS WHY THE OUTFLOW VALVE WOULD SUDDENLY GO FULL OPEN. AS AN ASIDE, I RATHER FORCEFULLY TOLD THE F/E TO GO FOR MANUAL 'BASED ON MY LONG (TOO LONG) EXPERIENCE AS A F/E ON VARIOUS ACFT.' IF HE HAD DONE THIS FIRST, I THINK WE COULD HAVE STOPPED THE CABIN CLIMB IN THIS SITUATION. MAYBE A WRONG RESPONSE ON THIS ACFT, THOUGH AS OUR CHECKLIST SAYS TO START AT THE TOP OF THE PANEL AND WORK DOWN. MANUAL AND VALVE POSITION IS THE LAST ITEM TO CHECK - WHY?

Data retrieved from NASA's ASRS site as of August 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.