Narrative:

I was working all of our area low sectors combined; (3 total). There were inbounds to several larger airports and the frequencies were a little congested. My d-side advised me aircraft X was calling me for clearance off pbx and we had a proposal strip for him in the bay. There was also traffic in the vicinity of pbx at 080; which is mainly why he alerted me to aircraft X's call. I transmitted to aircraft X to confirm he was calling center. He affirmed that he was 'off pbx instruments to ZZZ'; no altitude was stated. I gave aircraft X a squawk code. About 20 seconds later I saw a target on that code and the unverified mode C was 065. I wasn't aware of the type aircraft; and had forgotten that the weather was clear VFR. I just wanted to get aircraft X a clearance to 070 below my 080 traffic and let him tunnel underneath while I attended to my other traffic in the sectors. I issued a clearance to ZZZ 'via leaving 045 (which is our minimum vectoring altitude in that area) direct; climb and maintain 070 say altitude.' (to verify mode C) I expected him to say he was leveling at 070 when he read back the clearance. Aircraft X keyed up and said; 'we're already out of 070; we see the traffic on TCAS; we'll hurry on up with a good rate and you can reissue clearance when we get above if that's ok.' at the time he unkeyed his mike his mode C showed 078. I keyed up and said 'roger; maintain VFR' I started to ask for a report leaving 090 to reissue the clearance and I noticed his mode C was near 090; so I cleared him 'to ZZZ via leaving 090 direct climb and maintain 110; maintain VFR through 090; report leaving 090.' aircraft X's altitude read back this time was; 'ok; we're out of 098 climbing to 110.' conflict alert had activated and the omic (operations manager in charge) desk called the area to inquire about the alert. We told the controller in charge (controller in charge) that aircraft X was VFR. I believed the clearance to be void since he was above my assigned altitude and he wanted to stay VFR until above. I felt my clearance was in compliance with keeping him VFR until above the traffic. After a break and another session worked; the flm (front line manager) advised he wanted to watch the falcon of this event with me as the omic had watched it and wanted to impress upon me the importance of verifying mode C before issuing a clearance and/or calling traffic. I realize after watching it on falcon that it could've been handled differently. I just wanted to issue a clearance; basically non-radar; to the aircraft below my traffic and move on to higher priorities. I didn't feel I needed to call traffic if I was stopping aircraft X below the traffic. I wasn't aware of the type aircraft or that he was climbing like a rocket because he knew the traffic was out there from his TCAS. Most aircraft off these uncontrolled airports are smaller aircraft; and if I had seen a mode C of 065; it would be unusual for them to get above 070 in the time it takes to issue a clearance. The total time from when I asked if he was calling center until the start of my second IFR clearance was less than one minute and he had climbed between 2000-3000 ft. The next working day I was advised that this had been ruled by quality assurance as a proximity event.

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Original NASA ASRS Text

Title: ZID Controller experienced a proximity event involving an IFR aircraft that departed PBX VFR and climbed faster than expected; the reporter claimed no separation was compromised.

Narrative: I was working all of our area low sectors combined; (3 total). There were inbounds to several larger airports and the frequencies were a little congested. My D-side advised me Aircraft X was calling me for clearance off PBX and we had a proposal strip for him in the bay. There was also traffic in the vicinity of PBX at 080; which is mainly why he alerted me to Aircraft X's call. I transmitted to Aircraft X to confirm he was calling Center. He affirmed that he was 'off PBX instruments to ZZZ'; no altitude was stated. I gave Aircraft X a squawk code. About 20 seconds later I saw a target on that code and the unverified Mode C was 065. I wasn't aware of the type aircraft; and had forgotten that the weather was clear VFR. I just wanted to get Aircraft X a clearance to 070 below my 080 traffic and let him tunnel underneath while I attended to my other traffic in the sectors. I issued a clearance to ZZZ 'via leaving 045 (which is our minimum vectoring altitude in that area) direct; climb and maintain 070 say altitude.' (To verify Mode C) I expected him to say he was leveling at 070 when he read back the clearance. Aircraft X keyed up and said; 'We're already out of 070; we see the traffic on TCAS; we'll hurry on up with a good rate and you can reissue clearance when we get above if that's OK.' At the time he unkeyed his mike his Mode C showed 078. I keyed up and said 'ROGER; maintain VFR' I started to ask for a report leaving 090 to reissue the clearance and I noticed his Mode C was near 090; so I cleared him 'to ZZZ via leaving 090 direct climb and maintain 110; maintain VFR through 090; report leaving 090.' Aircraft X's altitude read back this time was; 'OK; we're out of 098 climbing to 110.' Conflict alert had activated and the OMIC (Operations Manager in Charge) desk called the area to inquire about the alert. We told the CIC (Controller in Charge) that Aircraft X was VFR. I believed the clearance to be void since he was above my assigned altitude and he wanted to stay VFR until above. I felt my clearance was in compliance with keeping him VFR until above the traffic. After a break and another session worked; the FLM (Front Line Manager) advised he wanted to watch the FALCON of this event with me as the OMIC had watched it and wanted to impress upon me the importance of verifying Mode C before issuing a clearance and/or calling traffic. I realize after watching it on FALCON that it could've been handled differently. I just wanted to issue a clearance; basically non-radar; to the aircraft below my traffic and move on to higher priorities. I didn't feel I needed to call traffic if I was stopping Aircraft X below the traffic. I wasn't aware of the type aircraft or that he was climbing like a rocket because he knew the traffic was out there from his TCAS. Most aircraft off these uncontrolled airports are smaller aircraft; and if I had seen a Mode C of 065; it would be unusual for them to get above 070 in the time it takes to issue a clearance. The total time from when I asked if he was calling center until the start of my second IFR clearance was less than one minute and he had climbed between 2000-3000 FT. The next working day I was advised that this had been ruled by Quality Assurance as a proximity event.

Data retrieved from NASA's ASRS site as of April 2012 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.