Narrative:

I was working departure/arrival west with a final. I had aircraft X descending via the arrival on the short side landing south. I flashed the aircraft to final; they accepted and transfer of communications was effected about 30 out. I accepted handoff from the east sector of aircraft Y. He was at 6000 on a 290ish heading landing jwn about 15 east. I was distracted with two 8000 overflights that were conflicting that the east sector had also just given me and didn't notice that aircraft X had missed his RNAV crossing restriction putting him head on with aircraft Y. I yelled back to final across the room that I was turning him. Final said ok. But unknown to me final had already turned aircraft X to avoid a conflict. It wasn't apparent due to the huge unsafe fusion radar delays that we are plagued with all in the name of 'nextgen.' unfortunately we had both turned them the same way and they were on a collision path rate with a 600 knot closure rate less than 6 miles apart at the same altitude. We got it straightened out and turned away from each other but I'm not sure if it was in time.RNAV is a disaster at bna. Aircraft X was the 5th or 6th aircraft unable to make the crossing restriction on the short side on my shift. As far as I know not a single A319 was able to do it plus aircraft X. We've had a rash of deals at bna because we are so incredibly covered up with workarounds circumnavigating our faulty RNAV procedures complicated by the increased workload of the 30 degree intercept for visual approaches. [Management] thought the way to fix this was to issue a mandate that every aircraft had to remain on the RNAV arrival. [Management does not] understand that the poorly written RNAV procedures along with the 30 degree intercept rules were the root of our deal spike. [Management] mistakenly thought that our RNAV procedures were written correctly and would help.best fix for this mess? We are running level 10 numbers; we need to start acting like it.1. Start the process for class B airspace.2. Fix the RNAV procedures so aircraft can actually fly them.3. Fix the RNAV departures so the aircraft can transition to center airspace with no other response than 'radar contact' our RNAV stops at 4000. Unbelievable. 4. We've checked out a lot of people here on the 'train to succeed program.' we need higher standards. We are now the busiest facility in the hub; we are woefully understaffed for our peak hours.5. Bring back final monitors from the hub and run simos.6. Currently; in our last briefing; we were told we could no longer use lateral separation but only altitude in the final box until both aircraft were established. This is unworkable; there aren't enough available altitudes. I was told that this knee jerk reaction from [management] is to avoid the scrutiny of the tiger team due to our 45+ deals in the last 6 months. Please; please send the tiger team. I don't have any faith in our leadership.

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Original NASA ASRS Text

Title: BNA TRACON Controller reported an unsafe situation related to the Fusion radar and the use of RNAV procedures.

Narrative: I was working departure/arrival west with a final. I had Aircraft X descending via the arrival on the short side landing south. I flashed the aircraft to final; they accepted and transfer of communications was effected about 30 out. I accepted handoff from the east sector of Aircraft Y. He was at 6000 on a 290ish heading landing JWN about 15 east. I was distracted with two 8000 overflights that were conflicting that the east sector had also just given me and didn't notice that Aircraft X had missed his RNAV crossing restriction putting him head on with Aircraft Y. I yelled back to final across the room that I was turning him. Final said ok. But unknown to me final had already turned Aircraft X to avoid a conflict. It wasn't apparent due to the huge unsafe Fusion radar delays that we are plagued with all in the name of 'NextGen.' Unfortunately we had both turned them the same way and they were on a collision path rate with a 600 knot closure rate less than 6 miles apart at the same altitude. We got it straightened out and turned away from each other but I'm not sure if it was in time.RNAV is a disaster at BNA. Aircraft X was the 5th or 6th aircraft unable to make the crossing restriction on the short side on my shift. As far as I know not a single A319 was able to do it plus Aircraft X. We've had a rash of deals at BNA because we are so incredibly covered up with workarounds circumnavigating our faulty RNAV procedures complicated by the increased workload of the 30 degree intercept for visual approaches. [Management] thought the way to fix this was to issue a mandate that every aircraft had to remain on the RNAV arrival. [Management does not] understand that the poorly written RNAV procedures along with the 30 degree intercept rules were the root of our deal spike. [Management] mistakenly thought that our RNAV procedures were written correctly and would help.Best fix for this mess? We are running level 10 numbers; we need to start acting like it.1. Start the process for Class B airspace.2. Fix the RNAV procedures so aircraft can actually fly them.3. Fix the RNAV departures so the aircraft can transition to Center airspace with no other response than 'radar contact' our RNAV stops at 4000. Unbelievable. 4. We've checked out a lot of people here on the 'train to succeed program.' We need higher standards. We are now the busiest facility in the hub; we are woefully understaffed for our peak hours.5. Bring back final monitors from the hub and run simos.6. Currently; in our last briefing; we were told we could no longer use lateral separation but only altitude in the final box until both aircraft were established. This is unworkable; there aren't enough available altitudes. I was told that this knee jerk reaction from [management] is to avoid the scrutiny of the Tiger team due to our 45+ deals in the last 6 months. Please; please send the Tiger team. I don't have any faith in our leadership.

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.