Narrative:

While working as a controller on the tar-H position at atl, I had a time arrival, air carrier X. This aircraft was given runway 27L for arrival to cross tiroe at or below 14000 ft descend and maintain 12000 ft. Air carrier X was later descended to 11000 ft. Another aircraft departing atl, air carrier Y, was climbed to 10000 ft by the controller working the departure radar south position. The climbing aircraft responded to a TCASII alert to climb resulting in the loss of separation. X responded that he was on a 030 degree heading and that was close with the departure. When the conflict alert sounded the departing aircraft's mode C indicated 10600 ft and the targets merged. The data blocks were also overlapping on the conflict alert. Traffic at this time was heavy during the inbound push. X landed at atl and the departure Y continued to sav. This type of TCASII response for the departure to climb above 10000 ft created a very close situation and made me very tense very quickly. From the time of the conflict alert there was not any time for me to assist as a controller. Supplemental information from acn 264636: air carrier X level at 11000 ft assigned on 030 degree heading for vectors to downwind leg landing runway 27L at atl. Position was 7-10 mi southwest of atl VORTAC. Received a TCASII RA generated by an aircraft (MD88) climbing through his assigned altitude of 10000 ft. We acquired him visually and expected his RA to be a nuisance RA since this is a common occurrence between inbounds level at 11000 ft and clbouts leveling at 10000 ft. When it became apparent that he was not leveling and continued to climb through our altitude, we took evasive action by turning left about 30 degrees of heading change. Cpa was approximately 1/2 mi. We elected not to follow the RA command due to potential traffic conflicts with additional traffic below the RA target climbing out on departure from atl. A horizontal escape maneuver was the safer course of action in this instance.

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Original NASA ASRS Text

Title: ACR Y TCASII RA CLB THROUGH OCCUPIED ALT HAD LTSS FROM ACR X. EVASIVE ACTION TAKEN BY ACR X.

Narrative: WHILE WORKING AS A CTLR ON THE TAR-H POS AT ATL, I HAD A TIME ARR, ACR X. THIS ACFT WAS GIVEN RWY 27L FOR ARR TO CROSS TIROE AT OR BELOW 14000 FT DSND AND MAINTAIN 12000 FT. ACR X WAS LATER DSNDED TO 11000 FT. ANOTHER ACFT DEPARTING ATL, ACR Y, WAS CLBED TO 10000 FT BY THE CTLR WORKING THE DEP RADAR S POS. THE CLBING ACFT RESPONDED TO A TCASII ALERT TO CLB RESULTING IN THE LOSS OF SEPARATION. X RESPONDED THAT HE WAS ON A 030 DEG HDG AND THAT WAS CLOSE WITH THE DEP. WHEN THE CONFLICT ALERT SOUNDED THE DEPARTING ACFT'S MODE C INDICATED 10600 FT AND THE TARGETS MERGED. THE DATA BLOCKS WERE ALSO OVERLAPPING ON THE CONFLICT ALERT. TFC AT THIS TIME WAS HVY DURING THE INBOUND PUSH. X LANDED AT ATL AND THE DEP Y CONTINUED TO SAV. THIS TYPE OF TCASII RESPONSE FOR THE DEP TO CLB ABOVE 10000 FT CREATED A VERY CLOSE SIT AND MADE ME VERY TENSE VERY QUICKLY. FROM THE TIME OF THE CONFLICT ALERT THERE WAS NOT ANY TIME FOR ME TO ASSIST AS A CTLR. SUPPLEMENTAL INFO FROM ACN 264636: ACR X LEVEL AT 11000 FT ASSIGNED ON 030 DEG HDG FOR VECTORS TO DOWNWIND LEG LNDG RWY 27L AT ATL. POS WAS 7-10 MI SW OF ATL VORTAC. RECEIVED A TCASII RA GENERATED BY AN ACFT (MD88) CLBING THROUGH HIS ASSIGNED ALT OF 10000 FT. WE ACQUIRED HIM VISUALLY AND EXPECTED HIS RA TO BE A NUISANCE RA SINCE THIS IS A COMMON OCCURRENCE BTWN INBOUNDS LEVEL AT 11000 FT AND CLBOUTS LEVELING AT 10000 FT. WHEN IT BECAME APPARENT THAT HE WAS NOT LEVELING AND CONTINUED TO CLB THROUGH OUR ALT, WE TOOK EVASIVE ACTION BY TURNING L ABOUT 30 DEGS OF HDG CHANGE. CPA WAS APPROX 1/2 MI. WE ELECTED NOT TO FOLLOW THE RA COMMAND DUE TO POTENTIAL TFC CONFLICTS WITH ADDITIONAL TFC BELOW THE RA TARGET CLBING OUT ON DEP FROM ATL. A HORIZ ESCAPE MANEUVER WAS THE SAFER COURSE OF ACTION IN THIS INSTANCE.

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.