B737 Undifferentiated or Other Model
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 6
Situational Awareness; Communication Breakdown
Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Air Traffic Control Separated Traffic
Human Factors; Procedure
I was working Radar at the HI ROCK sector; having just shortly before this event experienced another reported event. I pointed-out Aircraft X and Aircraft Y to the CLARK HILL sector climbing reference their Aircraft Z (at FL350). Both climbing aircraft were climbing well and requesting FL410 (and on similar routes before splitting into the Q-Route system). I did not notify the 2 aircraft of similar sounding call signs because the numbers were in no way similar; and they had been on the same 3 ZTL frequencies following each other. I applied merging target procedures between Aircraft Y (the trailing aircraft) and Aircraft Z and told the aircraft it would be 2 minutes for higher. Aircraft Y reported Aircraft Z in sight. Moment's later; I climbed Aircraft X to FL410. The read back was indecipherable and it was clear to me that both pilots had read back the clearance. As soon as their transmissions stopped; I keyed the microphone and said quickly '@ aircraft' read back that clearance; it was only for Aircraft X. Aircraft Y; maintain FL340.' Aircraft Y promptly read back 'Maintaining FL340' and I think apologized. 1 minute later; targets of Aircraft Y and Aircraft Z appeared to merge. A minute after that; I climbed Aircraft Y to FL410.It seems clear enough to me; that Aircraft Y heard '[company name]' and a climb to his requested altitude and assumed the clearance was for him.I took action as quickly as I could to prevent an event. Perhaps something Datacom can help fix.
ZTL Controller reported that two of the same company aircraft had similar sounding call signs and both aircraft responded to a climb clearance.