Narrative:

Called for taxi clearance while still on gate. Frequency was busy. Ground control called back with taxi clearance and route to take, however, call sign he used was 1 digit off (3 digit call sign). We both thought the clearance was for us as the route, runway, etc was normal and natural for our gate location and first fix after takeoff. We acknowledged the clearance, began our taxi, and attempted to correct our call sign with the controller. Controller was very busy, so we continued the taxi, realizing the controller missed the call sign. Both of us figured this was just another simple mistake of missing a call sign digit. Shortly after moving out from gate, and after passing several taxiway intxns, we realized that the clearance we took was for another aircraft at a gate on the same concourse with the same initial fix as ours, putting him on the same departure runway as us. The controller finally caught up with our flight and realized what we had done. We did not cross any runways and did not cut off any other traffic. We told ground control exactly what we had done, that we were in error and sorry for any problems and mix-ups. He then resequenced our flight and issued taxi clearance and a handoff to tower. We routinely fly through busy airline hubs and missing a call sign digit is a common occurrence by both controllers and crews alike. Callback conversation with reporter revealed the following information: the reporter flies the ATR-72 for a large regional air carrier. He is based temporarily in mia, away from his home base of ord. He and the first officer are good friends. The reporter 'trusts him completely.' with any other first officer, the captain 'might have stopped the aircraft and checked the clearance.' the other aircraft was of the same air carrier, same type aircraft, same runway, and same initial fix. The trip numbers were just 1 digit off. Ground control seemed to understand what the problem was and was not upset. The reporter had not crossed any runways or cut off any other aircraft. The reporter realizes that the only way to prevent this would be to force his way into ground control to verify the clearance.

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Original NASA ASRS Text

Title: FLC STARTED TO TAXI WITHOUT CLRNC.

Narrative: CALLED FOR TAXI CLRNC WHILE STILL ON GATE. FREQ WAS BUSY. GND CTL CALLED BACK WITH TAXI CLRNC AND RTE TO TAKE, HOWEVER, CALL SIGN HE USED WAS 1 DIGIT OFF (3 DIGIT CALL SIGN). WE BOTH THOUGHT THE CLRNC WAS FOR US AS THE RTE, RWY, ETC WAS NORMAL AND NATURAL FOR OUR GATE LOCATION AND FIRST FIX AFTER TKOF. WE ACKNOWLEDGED THE CLRNC, BEGAN OUR TAXI, AND ATTEMPTED TO CORRECT OUR CALL SIGN WITH THE CTLR. CTLR WAS VERY BUSY, SO WE CONTINUED THE TAXI, REALIZING THE CTLR MISSED THE CALL SIGN. BOTH OF US FIGURED THIS WAS JUST ANOTHER SIMPLE MISTAKE OF MISSING A CALL SIGN DIGIT. SHORTLY AFTER MOVING OUT FROM GATE, AND AFTER PASSING SEVERAL TXWY INTXNS, WE REALIZED THAT THE CLRNC WE TOOK WAS FOR ANOTHER ACFT AT A GATE ON THE SAME CONCOURSE WITH THE SAME INITIAL FIX AS OURS, PUTTING HIM ON THE SAME DEP RWY AS US. THE CTLR FINALLY CAUGHT UP WITH OUR FLT AND REALIZED WHAT WE HAD DONE. WE DID NOT CROSS ANY RWYS AND DID NOT CUT OFF ANY OTHER TFC. WE TOLD GND CTL EXACTLY WHAT WE HAD DONE, THAT WE WERE IN ERROR AND SORRY FOR ANY PROBS AND MIX-UPS. HE THEN RESEQUENCED OUR FLT AND ISSUED TAXI CLRNC AND A HDOF TO TWR. WE ROUTINELY FLY THROUGH BUSY AIRLINE HUBS AND MISSING A CALL SIGN DIGIT IS A COMMON OCCURRENCE BY BOTH CTLRS AND CREWS ALIKE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR FLIES THE ATR-72 FOR A LARGE REGIONAL ACR. HE IS BASED TEMPORARILY IN MIA, AWAY FROM HIS HOME BASE OF ORD. HE AND THE FO ARE GOOD FRIENDS. THE RPTR 'TRUSTS HIM COMPLETELY.' WITH ANY OTHER FO, THE CAPT 'MIGHT HAVE STOPPED THE ACFT AND CHKED THE CLRNC.' THE OTHER ACFT WAS OF THE SAME ACR, SAME TYPE ACFT, SAME RWY, AND SAME INITIAL FIX. THE TRIP NUMBERS WERE JUST 1 DIGIT OFF. GND CTL SEEMED TO UNDERSTAND WHAT THE PROB WAS AND WAS NOT UPSET. THE RPTR HAD NOT CROSSED ANY RWYS OR CUT OFF ANY OTHER ACFT. THE RPTR REALIZES THAT THE ONLY WAY TO PREVENT THIS WOULD BE TO FORCE HIS WAY INTO GND CTL TO VERIFY THE CLRNC.

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.