A DEP MD88 TAKES A HDG CLRNC MEANT FOR ANOTHER COMPANY FLT.

Narrative

DEP RWY 26L AT ATL. AFTER TKOF; TURNED INITIALLY TO HDG 285 DEGS. UPON SWITCHING TO DEP CTL AND PRIOR TO CONTACTING DEP CTL; WAS ISSUED A CLRNC TO TURN TO HDG 360 DEGS. AFTER ROLLING OUT ON 360 DEG HDG AND FLYING FOR APPROX 30 SECONDS TO 1 MIN; WAS ASKED BY DEP WHAT OUR HDG WAS. WE RESPONDED 360 DEGS AND DEP CTL TURNED US TO A HDG OF 260 DEGS. DEP CTL SAID THAT 360 DEG HDG WAS FOR XXBA (OUR CALL SIGN WAS XXLB). AFTER ROLLING OUT ON 260 DEG HDG; DEP CTL ISSUED A TA AT OUR 1 O'CLOCK POS; WHICH WAS AN ATR THAT DEPARTED RWY 26L JUST PRIOR TO US. (WE HAD A POSITIVE VISUAL CONTACT AT ALL TIMES WITH THIS ACFT.) DEP CTL THEN ISSUED AN AMENDED ALT OF 6000 FT MSL; AT WHICH WE LEVELED OFF. THE ATR THEN STARTED DSNDING FROM AN APPARENT RA/TA ADVISORY AND APPEARED TO GO THROUGH OUR ALT. WE NEVER RECEIVED ANYTHING OTHER THAN A TA FROM OUR TCASII WHICH WAS OPERATING NORMALLY. DEP CTL THEN GAVE US CLRNC TO GO L OR R TO AVOID THE ATR. I MADE A SLIGHT L TURN BUT THAT WAS REALLY NOT NECESSARY AS THERE WAS NEVER A TRUE CONFLICT AS TO AVOIDING THE ATR. IT APPEARED WE MAY HAVE COME WITHIN APPROX 1 MI OF THE ATR. AFTER PASSING ATR REST OF FLT UNEVENTFUL. ONE OTHER NOTE: AFTER RESPONDING TO DEP CTL'S 360 DEG HDG ON THE RADIO; NO OTHER ACFT RESPONDED AND DEP CTL DID NOT COME BACK IMMEDIATELY AND SAY THAT CLRNC WAS NOT FOR US. IT APPEARED THERE WAS A COM PROB AND IF ATC DID INDEED SAY THE CLRNC WAS FOR THE OTHER FLT HE DID NOT COME BACK AND CORRECT US WHEN WE ANSWERED WITH OUR CALL SIGN. THIS WAS THE 4TH AND LAST LEG OF A 12+ HR DAY FOR THE FLC WITH 2 EARLY GET-UPS IN A ROW. SUPPLEMENTAL INFO FROM ACN 430392: UPON SWITCHING TO DEP CTL AND PRIOR TO CONTACTING DEP CTL; WE WERE TOLD (HEARD HIM SAY) XXLB TURN TO HDG 360 DEGS.