Large transport with faulty TCASII equipment responds to RA. Altitude deviation.

Attributes
ACN	236722
Time
Date	199303
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mmzt
State Reference	FO
Altitude	msl bound lower : 33000 msl bound upper : 33700
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : mmzt
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 90 flight time total : 4000
ASRS Report	236722
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance non adherence : far other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

The aircraft we were flying had been brought to los angeles with a maintenance writeup stating the TCASII was not properly picking up targets. The TCASII should have been deactivated, the circuit breakers pulled and operated in the transponder on left mode. The breakers were not pulled and we operated the TCASII in the automatic mode and all seemed to function properly. Mazatlan center gave us a vector for traffic routing us between 2 aircraft. We received an RA and climbed following the TCASII command. We climbed 700 ft. The TCASII showed traffic to be 400 ft below us. ATC said the traffic was at FL290, 4000 ft below us. Passing visually we could see the traffic. It appeared to be at FL290. We should not have been operating the TCASII. ATC later advised us that the particular aircraft we were flying has had similar problems.

Original NASA ASRS Text

Title: LGT WITH FAULTY TCASII EQUIP RESPONDS TO RA. ALTDEV.

Narrative: THE ACFT WE WERE FLYING HAD BEEN BROUGHT TO LOS ANGELES WITH A MAINT WRITEUP STATING THE TCASII WAS NOT PROPERLY PICKING UP TARGETS. THE TCASII SHOULD HAVE BEEN DEACTIVATED, THE CIRCUIT BREAKERS PULLED AND OPERATED IN THE XPONDER ON L MODE. THE BREAKERS WERE NOT PULLED AND WE OPERATED THE TCASII IN THE AUTO MODE AND ALL SEEMED TO FUNCTION PROPERLY. MAZATLAN CTR GAVE US A VECTOR FOR TFC ROUTING US BTWN 2 ACFT. WE RECEIVED AN RA AND CLBED FOLLOWING THE TCASII COMMAND. WE CLBED 700 FT. THE TCASII SHOWED TFC TO BE 400 FT BELOW US. ATC SAID THE TFC WAS AT FL290, 4000 FT BELOW US. PASSING VISUALLY WE COULD SEE THE TFC. IT APPEARED TO BE AT FL290. WE SHOULD NOT HAVE BEEN OPERATING THE TCASII. ATC LATER ADVISED US THAT THE PARTICULAR ACFT WE WERE FLYING HAS HAD SIMILAR PROBS.

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.