Flight crew mistakenly believes they lost cabin pressurization.

Attributes
ACN	278572
Time
Date	199407
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : iah
State Reference	TX
Altitude	msl bound lower : 18000 msl bound upper : 24000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zfw
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 220 flight time total : 6000 flight time type : 3000
ASRS Report	278572
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe non adherence : far
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I felt a rapid climb in cabin pressurization and looked back to engineer's panel. He exclaimed 'I've lost the cabin' which I took to mean a complete depressurization. The captain told me to begin a descent. I put on my oxygen mask and nosed the aircraft over while looking for traffic on TCASII thinking we had a complete depressurization, I announced on the PA for passenger to put on oxygen masks. The masks had not deployed because we hadn't 'lost the cabin,' it was just climbing rapidly. The #1 flight attendant informed the engineer the masks were not down so he deployed them manually without realizing the cabin wasn't over 10000 ft. He had tried to ask the captain if he should, but it was impossible to communication with masks on and hot mikes. The procedure to put mikes to emergency caused the problem because of the inability for the captain to hear either center when he requested emergency descent or the engineer. We descended from FL240 to 18000 ft without knowing if center acknowledged our intentions. We continued flight at 10000 ft with no further incident.

Original NASA ASRS Text

Title: FLC MISTAKENLY BELIEVES THEY LOST CABIN PRESSURIZATION.

Narrative: I FELT A RAPID CLB IN CABIN PRESSURIZATION AND LOOKED BACK TO ENGINEER'S PANEL. HE EXCLAIMED 'I'VE LOST THE CABIN' WHICH I TOOK TO MEAN A COMPLETE DEPRESSURIZATION. THE CAPT TOLD ME TO BEGIN A DSCNT. I PUT ON MY OXYGEN MASK AND NOSED THE ACFT OVER WHILE LOOKING FOR TFC ON TCASII THINKING WE HAD A COMPLETE DEPRESSURIZATION, I ANNOUNCED ON THE PA FOR PAX TO PUT ON OXYGEN MASKS. THE MASKS HAD NOT DEPLOYED BECAUSE WE HADN'T 'LOST THE CABIN,' IT WAS JUST CLBING RAPIDLY. THE #1 FLT ATTENDANT INFORMED THE ENGINEER THE MASKS WERE NOT DOWN SO HE DEPLOYED THEM MANUALLY WITHOUT REALIZING THE CABIN WASN'T OVER 10000 FT. HE HAD TRIED TO ASK THE CAPT IF HE SHOULD, BUT IT WAS IMPOSSIBLE TO COM WITH MASKS ON AND HOT MIKES. THE PROC TO PUT MIKES TO EMER CAUSED THE PROB BECAUSE OF THE INABILITY FOR THE CAPT TO HEAR EITHER CTR WHEN HE REQUESTED EMER DSCNT OR THE ENGINEER. WE DSNDED FROM FL240 TO 18000 FT WITHOUT KNOWING IF CTR ACKNOWLEDGED OUR INTENTIONS. WE CONTINUED FLT AT 10000 FT WITH NO FURTHER INCIDENT.

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.