Narrative:

While on approach to runway 17C at dfw, TCASII gave an immediate 'climb now' RA with vsi indication of 1500 FPM climb. While responding to the RA, we climbed towards an MD80 1000 ft above our altitude. Notified ATC we were responding to the RA. We were told of the conflict, returned to our assigned altitude of 5000 ft. Total deviation of 500 ft. Callback conversation with reporter revealed the following information: the captain reporter, PNF, could not tell the analyst what make of TCASII they had installed on the ATR72. He does, however, believe it was a false warning, a ghost. The traffic was indicated at the same altitude as their aircraft and the TCASII had not issued a TA prior to the issuance of the RA. ATC did not see any traffic below or at the same altitude. At that time though, there was a lot of thunderstorm activity in the area, which was a distraction to both the flcs and ATC. The aircraft was IMC at the time and that was one reason for the altitude deviation altitude excursion and non adherence to ATC clearance. The captain noted traffic 'everywhere' and they were on vectors after a hectic WX whipped flight from little rock. The crew was task saturated. The captain waited for the third RA before he instructed the first officer to climb with the RA since he felt that the TCASII sometimes settles down after a false 'blurp' or two. The captain advised ATC who just about 'came out of his chair' and said, 'don't climb, there's crossing traffic above you at 6000 ft.' the ATR72 then popped out of the cloud at about 5500 ft and saw the crossing traffic. A week later the captain called the TRACON supervisor and discussed the matter with him. The supervisor said that the aircraft at 6000 ft did get an RA on the ATR72 and had started a climb as well. A real bump up operation. Supplemental information from acn 415626: we notified ATC of the RA and deviation and was instructed to descend immediately for crossing traffic.

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Original NASA ASRS Text

Title: AN ARR ATR72 FLC LEAVES THEIR ASSIGNED ALT OF 5000 FT WHEN RECEIVING A TCASII RA. WHILE ADVISING APCH CTLR OF SAME, CTLR ADVISES CREW TO RETURN TO 5000 FT BECAUSE OF XING TFC AT 6000 FT. MISS DISTANCE WAS 3000 FT HORIZ AND 550 FT VERT.

Narrative: WHILE ON APCH TO RWY 17C AT DFW, TCASII GAVE AN IMMEDIATE 'CLB NOW' RA WITH VSI INDICATION OF 1500 FPM CLB. WHILE RESPONDING TO THE RA, WE CLBED TOWARDS AN MD80 1000 FT ABOVE OUR ALT. NOTIFIED ATC WE WERE RESPONDING TO THE RA. WE WERE TOLD OF THE CONFLICT, RETURNED TO OUR ASSIGNED ALT OF 5000 FT. TOTAL DEV OF 500 FT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE CAPT RPTR, PNF, COULD NOT TELL THE ANALYST WHAT MAKE OF TCASII THEY HAD INSTALLED ON THE ATR72. HE DOES, HOWEVER, BELIEVE IT WAS A FALSE WARNING, A GHOST. THE TFC WAS INDICATED AT THE SAME ALT AS THEIR ACFT AND THE TCASII HAD NOT ISSUED A TA PRIOR TO THE ISSUANCE OF THE RA. ATC DID NOT SEE ANY TFC BELOW OR AT THE SAME ALT. AT THAT TIME THOUGH, THERE WAS A LOT OF TSTM ACTIVITY IN THE AREA, WHICH WAS A DISTR TO BOTH THE FLCS AND ATC. THE ACFT WAS IMC AT THE TIME AND THAT WAS ONE REASON FOR THE ALTDEV ALT EXCURSION AND NON ADHERENCE TO ATC CLRNC. THE CAPT NOTED TFC 'EVERYWHERE' AND THEY WERE ON VECTORS AFTER A HECTIC WX WHIPPED FLT FROM LITTLE ROCK. THE CREW WAS TASK SATURATED. THE CAPT WAITED FOR THE THIRD RA BEFORE HE INSTRUCTED THE FO TO CLB WITH THE RA SINCE HE FELT THAT THE TCASII SOMETIMES SETTLES DOWN AFTER A FALSE 'BLURP' OR TWO. THE CAPT ADVISED ATC WHO JUST ABOUT 'CAME OUT OF HIS CHAIR' AND SAID, 'DON'T CLB, THERE'S XING TFC ABOVE YOU AT 6000 FT.' THE ATR72 THEN POPPED OUT OF THE CLOUD AT ABOUT 5500 FT AND SAW THE XING TFC. A WK LATER THE CAPT CALLED THE TRACON SUPVR AND DISCUSSED THE MATTER WITH HIM. THE SUPVR SAID THAT THE ACFT AT 6000 FT DID GET AN RA ON THE ATR72 AND HAD STARTED A CLB AS WELL. A REAL BUMP UP OP. SUPPLEMENTAL INFO FROM ACN 415626: WE NOTIFIED ATC OF THE RA AND DEV AND WAS INSTRUCTED TO DSND IMMEDIATELY FOR XING TFC.

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.