Narrative:

Flight was level at FL310 at 290 KIAS approximately 25 mi north of fossl intersection (fossl 6 arrival) to phx and deviating north of the arrival course for WX. The sky was clear with good visibility at our position with a smooth ride. Then the TCASII immediately displayed a TCASII RA to climb to the green band (2500 FPM) with a target displayed in a red box (descending 00) symbol with arrow showing descent and '00' next to it at our 12 O'clock position directly off the nose of the aircraft and at our present position on our TCASII display. As the first officer flying, I immediately disconnected the autothrottles and autoplt and began to climb to the green band displayed on the TCASII in order to comply with the TCASII RA to climb. We visually did not see any conflicting traffic. During the climb, I notified ZAB that we were climbing in response to a TCASII RA. ZAB told us that there was no known traffic in our vicinity. We had climbed to about FL322 with the TCASII still displaying us to climb and target still directly in front of us at the same altitude. ZAB told us to descend back to FL310 and reconfirmed that he did not have any traffic at our altitude or near us. We descended back to FL310 and assumed the TCASII system must have had a system malfunction and continued the arrival and landed at phx airport. The TCASII system displayed the same conflict until about 100 ft above landing and had 2 more audio instructions to climb during the descent. The captain asked the flight attendants to do a cabin check for any portable electronic devices, but none were confirmed to be on. The captain notified our maintenance of the situation. A logbook entry of the event was made in the aircraft logbook.

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Original NASA ASRS Text

Title: B737-300 CREW HAD TCASII RA IN ZAB CLASS A AIRSPACE. TCASII WARNING PROVED TO BE A FALSE WARNING.

Narrative: FLT WAS LEVEL AT FL310 AT 290 KIAS APPROX 25 MI N OF FOSSL INTXN (FOSSL 6 ARR) TO PHX AND DEVIATING N OF THE ARR COURSE FOR WX. THE SKY WAS CLR WITH GOOD VISIBILITY AT OUR POS WITH A SMOOTH RIDE. THEN THE TCASII IMMEDIATELY DISPLAYED A TCASII RA TO CLB TO THE GREEN BAND (2500 FPM) WITH A TARGET DISPLAYED IN A RED BOX (DSNDING 00) SYMBOL WITH ARROW SHOWING DSCNT AND '00' NEXT TO IT AT OUR 12 O'CLOCK POS DIRECTLY OFF THE NOSE OF THE ACFT AND AT OUR PRESENT POS ON OUR TCASII DISPLAY. AS THE FO FLYING, I IMMEDIATELY DISCONNECTED THE AUTOTHROTTLES AND AUTOPLT AND BEGAN TO CLB TO THE GREEN BAND DISPLAYED ON THE TCASII IN ORDER TO COMPLY WITH THE TCASII RA TO CLB. WE VISUALLY DID NOT SEE ANY CONFLICTING TFC. DURING THE CLB, I NOTIFIED ZAB THAT WE WERE CLBING IN RESPONSE TO A TCASII RA. ZAB TOLD US THAT THERE WAS NO KNOWN TFC IN OUR VICINITY. WE HAD CLBED TO ABOUT FL322 WITH THE TCASII STILL DISPLAYING US TO CLB AND TARGET STILL DIRECTLY IN FRONT OF US AT THE SAME ALT. ZAB TOLD US TO DSND BACK TO FL310 AND RECONFIRMED THAT HE DID NOT HAVE ANY TFC AT OUR ALT OR NEAR US. WE DSNDED BACK TO FL310 AND ASSUMED THE TCASII SYS MUST HAVE HAD A SYS MALFUNCTION AND CONTINUED THE ARR AND LANDED AT PHX ARPT. THE TCASII SYS DISPLAYED THE SAME CONFLICT UNTIL ABOUT 100 FT ABOVE LNDG AND HAD 2 MORE AUDIO INSTRUCTIONS TO CLB DURING THE DSCNT. THE CAPT ASKED THE FLT ATTENDANTS TO DO A CABIN CHK FOR ANY PORTABLE ELECTRONIC DEVICES, BUT NONE WERE CONFIRMED TO BE ON. THE CAPT NOTIFIED OUR MAINT OF THE SIT. A LOGBOOK ENTRY OF THE EVENT WAS MADE IN THE ACFT LOGBOOK.

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.