Flight crew of medium large transport unable to control cabin pressure while in cruise at FL290.

Attributes
ACN	181405
Time
Date	199106
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mlc
State Reference	OK
Altitude	msl bound lower : 24000 msl bound upper : 29000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zfw tower : ict
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 180 flight time total : 12000 flight time type : 3800
ASRS Report	181405
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical altitude deviation : overshoot non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance flight crew : declared emergency other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

While en route dfw-stl, encountered uncontrollable loss of cabin pressure while cruising at FL290. Descent was immediately requested and granted by ZFW to a lower altitude. This altitude, 24000', represented the bottom of the high sector and was not sufficiently for our emergency situation. The controller coordination between the high sector and low sector was poor in that we were deterred from getting a lower altitude, even though the controller was aware of our loss of cabin pressure situation. (I reported this when I initiated the original request for clearance to 10000'.) while the captain flew and I ran checklists and configured switches, we may have inadvertently descended below the high sectors base assigned altitude after attempting to level off with aircraft configured for the rapid descent (spoilers out, etc) at about 24000'. The cabin's continued ascent required we continue down. It was then that we finally got a clearance to a lower altitude that fit our needs (10000'). The continued need to request lower, even though the controller knew we had a problem, was very distracting and made the workload for a 2-M crew overly burdensome. Descent below 24000' was accompanied by a handoff to ZKC. I feel the slow response in getting a sufficiently lower altitude was due to slow coordination between the high and low sectors, and was compounded by the handoff between centers. Quicker controller response time to a pilot's request for lower altitude during this type situation is needed. Also, controller awareness of what 'rapid depressurization' entails would also be helpful.

Original NASA ASRS Text

Title: FLT CREW OF MLG UNABLE TO CTL CABIN PRESSURE WHILE IN CRUISE AT FL290.

Narrative: WHILE ENRTE DFW-STL, ENCOUNTERED UNCONTROLLABLE LOSS OF CABIN PRESSURE WHILE CRUISING AT FL290. DSNT WAS IMMEDIATELY REQUESTED AND GRANTED BY ZFW TO A LOWER ALT. THIS ALT, 24000', REPRESENTED THE BOTTOM OF THE HIGH SECTOR AND WAS NOT SUFFICIENTLY FOR OUR EMER SITUATION. THE CTLR COORD BTWN THE HIGH SECTOR AND LOW SECTOR WAS POOR IN THAT WE WERE DETERRED FROM GETTING A LOWER ALT, EVEN THOUGH THE CTLR WAS AWARE OF OUR LOSS OF CABIN PRESSURE SITUATION. (I RPTED THIS WHEN I INITIATED THE ORIGINAL REQUEST FOR CLRNC TO 10000'.) WHILE THE CAPT FLEW AND I RAN CHKLISTS AND CONFIGURED SWITCHES, WE MAY HAVE INADVERTENTLY DSNDED BELOW THE HIGH SECTORS BASE ASSIGNED ALT AFTER ATTEMPTING TO LEVEL OFF WITH ACFT CONFIGURED FOR THE RAPID DSNT (SPOILERS OUT, ETC) AT ABOUT 24000'. THE CABIN'S CONTINUED ASCENT REQUIRED WE CONTINUE DOWN. IT WAS THEN THAT WE FINALLY GOT A CLRNC TO A LOWER ALT THAT FIT OUR NEEDS (10000'). THE CONTINUED NEED TO REQUEST LOWER, EVEN THOUGH THE CTLR KNEW WE HAD A PROB, WAS VERY DISTRACTING AND MADE THE WORKLOAD FOR A 2-M CREW OVERLY BURDENSOME. DSNT BELOW 24000' WAS ACCOMPANIED BY A HDOF TO ZKC. I FEEL THE SLOW RESPONSE IN GETTING A SUFFICIENTLY LOWER ALT WAS DUE TO SLOW COORD BTWN THE HIGH AND LOW SECTORS, AND WAS COMPOUNDED BY THE HDOF BTWN CENTERS. QUICKER CTLR RESPONSE TIME TO A PLT'S REQUEST FOR LOWER ALT DURING THIS TYPE SITUATION IS NEEDED. ALSO, CTLR AWARENESS OF WHAT 'RAPID DEPRESSURIZATION' ENTAILS WOULD ALSO BE HELPFUL.

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.