Narrative:

We were air carrier X. Air carrier Y heavy was also on frequency. We checked on ZDV about the same time. Center pointed out the similar call signs, and both aircraft acknowledged. Some time later, we requested a climb from our current altitude of FL290 to FL330. Center said we had opposite direction traffic and to expect climb clearance when clear. Mins later, center cleared us to climb to FL330 and I started a climb of approximately 1500 FPM. Less than a min later, center told air carrier Y to turn right (20 to 30 degrees) for traffic, and air carrier Y acknowledged. I visually acquired air carrier Y's (same direction, ahead, and high) turn. An estimated 15-20 seconds later, center directed air carrier Y an additional 30 degrees of turn with excitement/stress audible in his voice. The captain tried several times to confirm with center that the requested turn might be for us, but he was blocked. Several calls were made between center and air carrier Y. Center trying to confirm air carrier Y was in a turn (or to increase rate). Another center call directed an air carrier Z to stop a climb and/or descend to FL280 or FL290 (I can't be sure). All this radio traffic was going back and forth in about 15-20 seconds. At some time during this exchange, our TCASII called 'traffic' followed very shortly by RA instructions. I disengaged the autoplt and set the vvi in the green arc, approximately 2500-3000 FPM climb. The RA resolved before we reached FL330. I think center cleared us into conflicting, opposite direction traffic, air carrier Z. The similar call signs were definitely a contributing factor, because the wrong aircraft was turned initially and there was no time to sort it all out. I don't think there would have been a midair collision, but TCASII prevented a near miss. It was nice to have TCASII in this situation.

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Original NASA ASRS Text

Title: SIMILAR CALLSIGNS ACR X CLB THROUGH OCCUPIED ALT HAD LTSS FROM ACR Z. SYS ERROR.

Narrative: WE WERE ACR X. ACR Y HVY WAS ALSO ON FREQ. WE CHKED ON ZDV ABOUT THE SAME TIME. CTR POINTED OUT THE SIMILAR CALL SIGNS, AND BOTH ACFT ACKNOWLEDGED. SOME TIME LATER, WE REQUESTED A CLB FROM OUR CURRENT ALT OF FL290 TO FL330. CTR SAID WE HAD OPPOSITE DIRECTION TFC AND TO EXPECT CLB CLRNC WHEN CLR. MINS LATER, CTR CLRED US TO CLB TO FL330 AND I STARTED A CLB OF APPROX 1500 FPM. LESS THAN A MIN LATER, CTR TOLD ACR Y TO TURN R (20 TO 30 DEGS) FOR TFC, AND ACR Y ACKNOWLEDGED. I VISUALLY ACQUIRED ACR Y'S (SAME DIRECTION, AHEAD, AND HIGH) TURN. AN ESTIMATED 15-20 SECONDS LATER, CTR DIRECTED ACR Y AN ADDITIONAL 30 DEGS OF TURN WITH EXCITEMENT/STRESS AUDIBLE IN HIS VOICE. THE CAPT TRIED SEVERAL TIMES TO CONFIRM WITH CTR THAT THE REQUESTED TURN MIGHT BE FOR US, BUT HE WAS BLOCKED. SEVERAL CALLS WERE MADE BTWN CTR AND ACR Y. CTR TRYING TO CONFIRM ACR Y WAS IN A TURN (OR TO INCREASE RATE). ANOTHER CTR CALL DIRECTED AN ACR Z TO STOP A CLB AND/OR DSND TO FL280 OR FL290 (I CAN'T BE SURE). ALL THIS RADIO TFC WAS GOING BACK AND FORTH IN ABOUT 15-20 SECONDS. AT SOME TIME DURING THIS EXCHANGE, OUR TCASII CALLED 'TFC' FOLLOWED VERY SHORTLY BY RA INSTRUCTIONS. I DISENGAGED THE AUTOPLT AND SET THE VVI IN THE GREEN ARC, APPROX 2500-3000 FPM CLB. THE RA RESOLVED BEFORE WE REACHED FL330. I THINK CTR CLRED US INTO CONFLICTING, OPPOSITE DIRECTION TFC, ACR Z. THE SIMILAR CALL SIGNS WERE DEFINITELY A CONTRIBUTING FACTOR, BECAUSE THE WRONG ACFT WAS TURNED INITIALLY AND THERE WAS NO TIME TO SORT IT ALL OUT. I DON'T THINK THERE WOULD HAVE BEEN A MIDAIR COLLISION, BUT TCASII PREVENTED A NEAR MISS. IT WAS NICE TO HAVE TCASII IN THIS SIT.

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.