Unable to maintain pressurization. Return land.

Attributes
ACN	93641
Time
Date	198809
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : mck
State Reference	NE
Altitude	msl bound lower : 8000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute airway : j130
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : commercial pilot : atp pilot : instrument
Experience	flight time last 90 days : 240 flight time total : 8000 flight time type : 500
ASRS Report	93641
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : commercial pilot : instrument pilot : cfi pilot : atp
Experience	flight time last 90 days : 170 flight time total : 5000
ASRS Report	93921
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

At cruise altitude of 33000', aircraft began to lose cabin pressure. It was noted at that time that the left air conditioning pack had dropped off. The use of flight manual abnormal checklist procedures did not restore the pack or stop the cabin pressure climb. A descent to 24000' was requested and approved. When it became apparent that we could not hold cabin altitude constant at FL240, a further descent to 8000' was requested and approved. We returned to denver. One elderly female passenger with a history of heart problems became ill and was administered supplemental oxygen by the F/a's. She was released by medical personnel shortly after arrival in denver. No further problems were encountered.

Original NASA ASRS Text

Title: UNABLE TO MAINTAIN PRESSURIZATION. RETURN LAND.

Narrative: AT CRUISE ALT OF 33000', ACFT BEGAN TO LOSE CABIN PRESSURE. IT WAS NOTED AT THAT TIME THAT THE L AIR CONDITIONING PACK HAD DROPPED OFF. THE USE OF FLT MANUAL ABNORMAL CHKLIST PROCS DID NOT RESTORE THE PACK OR STOP THE CABIN PRESSURE CLB. A DSCNT TO 24000' WAS REQUESTED AND APPROVED. WHEN IT BECAME APPARENT THAT WE COULD NOT HOLD CABIN ALT CONSTANT AT FL240, A FURTHER DSCNT TO 8000' WAS REQUESTED AND APPROVED. WE RETURNED TO DENVER. ONE ELDERLY FEMALE PAX WITH A HISTORY OF HEART PROBS BECAME ILL AND WAS ADMINISTERED SUPPLEMENTAL OXYGEN BY THE F/A'S. SHE WAS RELEASED BY MEDICAL PERSONNEL SHORTLY AFTER ARR IN DENVER. NO FURTHER PROBS WERE ENCOUNTERED.

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.