Narrative:

Aircraft X was a departure level at 16000 feet on a westbound route. Aircraft Y was on a southwest bound route. I initially climbed aircraft Y to 15000 feet and issued traffic to both aircraft. Aircraft Y reported aircraft X in sight and since they were the only two aircraft in the vicinity and it appeared aircraft Y would be crossing behind the path of aircraft X. I instructed aircraft Y to maintain visual separation and climb to 23000 feet. I did not clearly understand aircraft Y 's read back the first time so I restated and asked for clarification that he would maintain visual separation. He responded that he would. I then told aircraft X that the other traffic had him in sight and would be climbing visually behind him. At the point that I made the decision to apply visual separation rules. The speed and climb rate of aircraft Y led me to think that he would be passing behind aircraft X and targets would not merge. Aircraft X then reported that he was responding to an resolution advisory (RA) and was climbing. I then verified again that aircraft Y still had the aircraft in sight. Aircraft Y responded that he did and I told him that aircraft X was responding to an RA and climbing now. Aircraft X then stated his concern for an aircraft getting that close to him and aircraft Y stated that they weren't that close. I don't think I would leave separation decisions to a general aviation pilot when an airline carrying hundreds of passengers are involved. Although visual separation is a tool to expedite traffic flow in this situation it would have only been a minute delay before the aircraft could continue his climb.

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Original NASA ASRS Text

Title: Air Traffic Controller and Air Taxi Captain reported another aircraft had to respond to an RA and told the controller the climbing aircraft was too close.

Narrative: Aircraft X was a departure level at 16000 feet on a westbound route. Aircraft Y was on a southwest bound route. I initially climbed Aircraft Y to 15000 feet and issued traffic to both aircraft. Aircraft Y reported Aircraft X in sight and since they were the only two aircraft in the vicinity and it appeared Aircraft Y would be crossing behind the path of Aircraft X. I instructed Aircraft Y to maintain visual separation and climb to 23000 feet. I did not clearly understand Aircraft Y 's read back the first time so I restated and asked for clarification that he would maintain visual separation. He responded that he would. I then told Aircraft X that the other traffic had him in sight and would be climbing visually behind him. At the point that I made the decision to apply visual separation rules. The speed and climb rate of Aircraft Y led me to think that he would be passing behind Aircraft X and targets would not merge. Aircraft X then reported that he was responding to an Resolution Advisory (RA) and was climbing. I then verified again that Aircraft Y still had the aircraft in sight. Aircraft Y responded that he did and I told him that Aircraft X was responding to an RA and climbing now. Aircraft X then stated his concern for an aircraft getting that close to him and Aircraft Y stated that they weren't that close. I don't think I would leave separation decisions to a general aviation pilot when an airline carrying hundreds of passengers are involved. Although visual separation is a tool to expedite traffic flow in this situation it would have only been a minute delay before the aircraft could continue his climb.

Data retrieved from NASA's ASRS site 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.