Narrative:

Our first flight of the day was flight xab, atl to clt. It proceeded normally and we changed planes in charlotte. Our next flight was flight xa, clt back to atl. We got the clearance, flight plan, taxi out and takeoff normally as flight xa and proceeded to our destination of atl. When we were on departure control, the first officer started to use the call sign xab of our previous flight by accident instead of flight xa. (By the way, flight xab was to continue from charlotte to gsp.) at the same time, which happened to be along our same filed routing to atl. As we proceeded along our filed routing to atl, ATC leveled us at 10000 ft and told us to contact gsp tower. We then realized atl thought we were landing at gsp and we told them we accidentally started using the wrong call sign. As we were not off course or causing a conflict, they understood the mistake and had us do a 360 degree turn to help sequence into the traffic flow to atl in the filed STAR. They climbed us up to altitude and the rest of the flight proceeded normally. The mistake was caused by accidently looking at the wrong call sign on the yoke clip board and we or ATC didn't catch at first that we started using the wrong call sign. More vigilance in our readbacks and larger numbers written in front of us on our clip board might have prevented us from accidentally using the wrong one part way through the flight. The other flight number was written on the yoke paper earlier and wasn't crossed out properly. Supplemental information from acn 268971: I got our clearance via pre departure clearance for our flight from clt to atl as flight xa. Somewhere between pushback and departure I started using our old flight number from the previous leg, flight xab.

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Original NASA ASRS Text

Title: ACFT USING WRONG CALL SIGN.

Narrative: OUR FIRST FLT OF THE DAY WAS FLT XAB, ATL TO CLT. IT PROCEEDED NORMALLY AND WE CHANGED PLANES IN CHARLOTTE. OUR NEXT FLT WAS FLT XA, CLT BACK TO ATL. WE GOT THE CLRNC, FLT PLAN, TAXI OUT AND TKOF NORMALLY AS FLT XA AND PROCEEDED TO OUR DEST OF ATL. WHEN WE WERE ON DEP CTL, THE FO STARTED TO USE THE CALL SIGN XAB OF OUR PREVIOUS FLT BY ACCIDENT INSTEAD OF FLT XA. (BY THE WAY, FLT XAB WAS TO CONTINUE FROM CHARLOTTE TO GSP.) AT THE SAME TIME, WHICH HAPPENED TO BE ALONG OUR SAME FILED ROUTING TO ATL. AS WE PROCEEDED ALONG OUR FILED ROUTING TO ATL, ATC LEVELED US AT 10000 FT AND TOLD US TO CONTACT GSP TWR. WE THEN REALIZED ATL THOUGHT WE WERE LNDG AT GSP AND WE TOLD THEM WE ACCIDENTALLY STARTED USING THE WRONG CALL SIGN. AS WE WERE NOT OFF COURSE OR CAUSING A CONFLICT, THEY UNDERSTOOD THE MISTAKE AND HAD US DO A 360 DEG TURN TO HELP SEQUENCE INTO THE TFC FLOW TO ATL IN THE FILED STAR. THEY CLBED US UP TO ALT AND THE REST OF THE FLT PROCEEDED NORMALLY. THE MISTAKE WAS CAUSED BY ACCIDENTLY LOOKING AT THE WRONG CALL SIGN ON THE YOKE CLIP BOARD AND WE OR ATC DIDN'T CATCH AT FIRST THAT WE STARTED USING THE WRONG CALL SIGN. MORE VIGILANCE IN OUR READBACKS AND LARGER NUMBERS WRITTEN IN FRONT OF US ON OUR CLIP BOARD MIGHT HAVE PREVENTED US FROM ACCIDENTALLY USING THE WRONG ONE PART WAY THROUGH THE FLT. THE OTHER FLT NUMBER WAS WRITTEN ON THE YOKE PAPER EARLIER AND WASN'T CROSSED OUT PROPERLY. SUPPLEMENTAL INFO FROM ACN 268971: I GOT OUR CLRNC VIA PDC FOR OUR FLT FROM CLT TO ATL AS FLT XA. SOMEWHERE BTWN PUSHBACK AND DEP I STARTED USING OUR OLD FLT NUMBER FROM THE PREVIOUS LEG, FLT XAB.

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.