Narrative:

I was conducting OJT at the time of the incident; and plugged in for almost 90 minutes. Complexity and volume were high but the sector was kept under control. Aircraft Y was originally climbed to FL150; 1;000 ft below aircraft X who was level at FL160. After analyzing; my trainee climbed aircraft Y to FL230. Both aircraft were in a 3 mile area; and I was comfortable with his decision. Aircraft Y was assigned a speed of 300 KTS for in trail spacing on the cshel SID. As the aircraft got closer; and converging; I noticed that aircraft Y's speed had slightly increased and instructed my trainee to turn him 20 degrees right to ensure 3 mile separation. My trainee also expedited the descent of aircraft X. According to conflict alert which had activated at the sector; closest proximity was 4.093 miles; which I had written down for training debrief. Aircraft Y was then turned back to lal and we carried on. We were made aware of a loss when I returned to work this afternoon. I immediately requested to go look at the situation on falcon since I did remember it; and had also written own the ca mileage of 4.093. We reviewed falcon and verified closest proximity of 4.0! I informed my supervisor and then had our OM look at it; same thing; no loss; and 4.0 in a 3 mile area. We then proceeded upstairs to qa. Qa pulled up the situation on FALCON3; and not the FALCON2 which is available downstairs to us. FALCON3 showed a loss at 2.98 miles. How is it that I am working radar; observe conflict alert closest proximity at 4.093; and not think twice about it; and then come back to work and find out it was 2.98? Am I to trust the mileage I observe and use everyday on my display? How is the data different on my display; FALCON2; and then FALCON3?use 6 miles since I cannot trust what I see on my display.

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Original NASA ASRS Text

Title: Two Controllers report of finding out about a loss of separation after returning to work. Two different types of replay instruments were used and one showed a loss of separation; while the other did not.

Narrative: I was conducting OJT at the time of the incident; and plugged in for almost 90 minutes. Complexity and volume were high but the sector was kept under control. Aircraft Y was originally climbed to FL150; 1;000 FT below Aircraft X who was level at FL160. After analyzing; my trainee climbed Aircraft Y to FL230. Both aircraft were in a 3 mile area; and I was comfortable with his decision. Aircraft Y was assigned a speed of 300 KTS for in trail spacing on the CSHEL SID. As the aircraft got closer; and converging; I noticed that Aircraft Y's speed had slightly increased and instructed my trainee to turn him 20 degrees right to ensure 3 mile separation. My trainee also expedited the descent of Aircraft X. According to conflict alert which had activated at the sector; closest proximity was 4.093 miles; which I had written down for training debrief. Aircraft Y was then turned back to LAL and we carried on. We were made aware of a loss when I returned to work this afternoon. I immediately requested to go look at the situation on FALCON since I did remember it; and had also written own the CA mileage of 4.093. We reviewed FALCON and verified closest proximity of 4.0! I informed my Supervisor and then had our OM look at it; same thing; no loss; and 4.0 in a 3 mile area. We then proceeded upstairs to QA. QA pulled up the situation on FALCON3; and not the FALCON2 which is available downstairs to us. FALCON3 showed a loss at 2.98 miles. How is it that I am working radar; observe conflict alert closest proximity at 4.093; and not think twice about it; and then come back to work and find out it was 2.98? Am I to trust the mileage I observe and use everyday on my display? How is the data different on my display; FALCON2; and then FALCON3?Use 6 miles since I cannot trust what I see on my display.

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.