At FL330 climbing a B737-300's TCAS failed; autothrottles disconnected; GPWS failed and cabin pressu...

Attributes
ACN	790904
Time
Date	200806
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 33000
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Route In Use	departure sid : n/s
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 120 flight time total : 8000 flight time type : 4400
ASRS Report	790904
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 125 flight time total : 8000 flight time type : 800
ASRS Report	790906
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper maintenance
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : took evasive action flight crew : declared emergency flight crew : landed in emergency condition other
Consequence	other
Supplementary
Problem Areas	Maintenance Human Performance Aircraft
Primary Problem	Aircraft

Narrative:

Takeoff and climb out of ZZZ initially went fine. Between 25000-30000 ft we got a TCAS fail. Shortly after that we noticed that we had an autothrottle disconnect. We did not get an autothrottle disconnect light associated with the disconnect. The next thing that we noticed was a GPWS light. We had read in the history of the plane that there had been an air/ground sensor problem the day prior; so we thought that this may be the problem we are having. Looked at the ACARS and noticed that we had a land time showing; which confirmed to us that the plane thought it was on the ground. Around 33000-34000 ft we started to get the takeoff warning horn. I looked up at the pressurization panel and all switches were correct and noticed the cabin altitude was at 10000 ft. We put on our oxygen masks and established communication. I requested lower altitude and was initially denied. I declared an emergency and we started down. While doing this I pulled the qrc out and ran the checklist for intermittent takeoff warning horn/depressurization. I went to manual on the pressurization panel and closed the outflow valve. When I looked at the valve position it looked to be mostly closed. I would estimate that it was about 15% open before I closed it. The pressurization did not automatically go to standby when it had failed. The highest the cabin altitude reached was about 11000 ft. During the descent we got low idle light with throttles at idle. I told the a flight attendant that we were returning to ZZZ and to do a cabin advisory and that we would be on the ground soon. I also told her that we should have a normal landing and taxi back to the gate. I contacted dispatch and asked for maintenance control to join in. We didn't get to say much to dispatch due to time constraints. Initially; we were going to hold to sort things out and then got an aft cargo light. We noticed that we were down to 114000 ft and decided that we had our ducks in a row and decided to go ahead and just continue to land. We ran appropriate checklists and proceeded to land normally and taxi back to gate.

Original NASA ASRS Text

Title: AT FL330 CLBING A B737-300'S TCAS FAILED; AUTOTHROTTLES DISCONNECTED; GPWS FAILED AND CABIN PRESSURE EXCEEDED 10000 FT. THE GND/AIR SENSE SWITCH FAILED. AN EMER WAS DECLARED WITH A RETURN TO LAND. THIS IS A REPEAT ANOMALY.

Narrative: TKOF AND CLB OUT OF ZZZ INITIALLY WENT FINE. BTWN 25000-30000 FT WE GOT A TCAS FAIL. SHORTLY AFTER THAT WE NOTICED THAT WE HAD AN AUTOTHROTTLE DISCONNECT. WE DID NOT GET AN AUTOTHROTTLE DISCONNECT LIGHT ASSOCIATED WITH THE DISCONNECT. THE NEXT THING THAT WE NOTICED WAS A GPWS LIGHT. WE HAD READ IN THE HISTORY OF THE PLANE THAT THERE HAD BEEN AN AIR/GND SENSOR PROB THE DAY PRIOR; SO WE THOUGHT THAT THIS MAY BE THE PROB WE ARE HAVING. LOOKED AT THE ACARS AND NOTICED THAT WE HAD A LAND TIME SHOWING; WHICH CONFIRMED TO US THAT THE PLANE THOUGHT IT WAS ON THE GND. AROUND 33000-34000 FT WE STARTED TO GET THE TKOF WARNING HORN. I LOOKED UP AT THE PRESSURIZATION PANEL AND ALL SWITCHES WERE CORRECT AND NOTICED THE CABIN ALT WAS AT 10000 FT. WE PUT ON OUR OXYGEN MASKS AND ESTABLISHED COM. I REQUESTED LOWER ALT AND WAS INITIALLY DENIED. I DECLARED AN EMER AND WE STARTED DOWN. WHILE DOING THIS I PULLED THE QRC OUT AND RAN THE CHKLIST FOR INTERMITTENT TKOF WARNING HORN/DEPRESSURIZATION. I WENT TO MANUAL ON THE PRESSURIZATION PANEL AND CLOSED THE OUTFLOW VALVE. WHEN I LOOKED AT THE VALVE POS IT LOOKED TO BE MOSTLY CLOSED. I WOULD ESTIMATE THAT IT WAS ABOUT 15% OPEN BEFORE I CLOSED IT. THE PRESSURIZATION DID NOT AUTOMATICALLY GO TO STANDBY WHEN IT HAD FAILED. THE HIGHEST THE CABIN ALT REACHED WAS ABOUT 11000 FT. DURING THE DSCNT WE GOT LOW IDLE LIGHT WITH THROTTLES AT IDLE. I TOLD THE A FLT ATTENDANT THAT WE WERE RETURNING TO ZZZ AND TO DO A CABIN ADVISORY AND THAT WE WOULD BE ON THE GND SOON. I ALSO TOLD HER THAT WE SHOULD HAVE A NORMAL LNDG AND TAXI BACK TO THE GATE. I CONTACTED DISPATCH AND ASKED FOR MAINT CTL TO JOIN IN. WE DIDN'T GET TO SAY MUCH TO DISPATCH DUE TO TIME CONSTRAINTS. INITIALLY; WE WERE GOING TO HOLD TO SORT THINGS OUT AND THEN GOT AN AFT CARGO LIGHT. WE NOTICED THAT WE WERE DOWN TO 114000 FT AND DECIDED THAT WE HAD OUR DUCKS IN A ROW AND DECIDED TO GO AHEAD AND JUST CONTINUE TO LAND. WE RAN APPROPRIATE CHKLISTS AND PROCEEDED TO LAND NORMALLY AND TAXI BACK TO GATE.

Data retrieved from NASA's ASRS site as of May 2009 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.

At FL330 climbing a B737-300's TCAS failed; autothrottles disconnected; GPWS failed and cabin pressure exceeded 10000 ft. The ground/air sense switch failed. An emergency was declared with a return to land. This is a repeat anomaly.