Airbus loses pressurization over nassau, descends prior to receiving clearance and returns to miami.

Attributes
ACN	458790
Time
Date	199912
Day	Sat
Local Time Of Day	1801 To 2400
Place
State Reference	FO
Altitude	msl bound lower : 10000 msl bound upper : 33000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	A300
Navigation In Use	other
Flight Phase	cruise : level
Route In Use	enroute : atlantic
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp pilot : multi engine
Experience	flight time last 90 days : 150 flight time total : 6900 flight time type : 200
ASRS Report	458790
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
ASRS Report	458925
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : cabin altitude warning other flight crewa other flight crewb
Resolutory Action	flight crew : declared emergency other
Consequence	other
Factors
Maintenance	performance deficiency : repair performance deficiency : inspection
Supplementary
Problem Areas	Maintenance Human Performance Flight Crew Human Performance Aircraft
Primary Problem	Maintenance Human Performance

Narrative:

An excessive cabin altitude warning was triggered and we initiated an emergency descent to 10000 ft prior to contact with ATC. We later were able to raise ATC and advise them of the nature of the emergency and requested a turn around to mia. The oxygen masks were deployed in the cabin and we continued along our vectored course at 10000 ft. This problem was caused by it would seem a valve that was improperly positioned in compliance with an MEL.

Original NASA ASRS Text

Title: AIRBUS LOSES PRESSURIZATION OVER NASSAU, DSNDS PRIOR TO RECEIVING CLRNC AND RETURNS TO MIAMI.

Narrative: AN EXCESSIVE CABIN ALT WARNING WAS TRIGGERED AND WE INITIATED AN EMER DSCNT TO 10000 FT PRIOR TO CONTACT WITH ATC. WE LATER WERE ABLE TO RAISE ATC AND ADVISE THEM OF THE NATURE OF THE EMER AND REQUESTED A TURN AROUND TO MIA. THE OXYGEN MASKS WERE DEPLOYED IN THE CABIN AND WE CONTINUED ALONG OUR VECTORED COURSE AT 10000 FT. THIS PROB WAS CAUSED BY IT WOULD SEEM A VALVE THAT WAS IMPROPERLY POSITIONED IN COMPLIANCE WITH AN MEL.

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.