Narrative:

Saw overtake on slowly converging rtes. Turned slower, front aircraft 30 degrees to left and faster, back aircraft 10 degrees right, to cross before overtake made it too late. It looked like I'd have 5 NM bare separation. Conflict alert activated, but was more of a distraction in this case because it was a controled situation and the lag inherent in conflict alert made it unreliable. The rules require 5 NM separation. If a controller uses 5 NM separation and is comfortable with it, as I have done my entire career, then on rare occasions he or she will come up a little short. The situation did not compromise safety in any way. The system worked in this case. We missed by 5 NM because we are human and humans make mistakes. The 5 mi rule is the buffer. I am glad it is there. You can't tell a controller to go for more separation than required and you can't lower the bar when the buffer is breached. Tell us the standard, I'll make it happen. Unfortunately, I am human, I do make mistakes. The benefits of having a human in the loop far and away overshadow the simple negative. In my 13 yrs as a radar controller, I can't guess how many times I have effectively handled sits all with 100% accuracy. I don't plan to change the way I work in any way. I am the best at what I do. Any real ATC controller worth a nickel would say the same. The system is safe.

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Original NASA ASRS Text

Title: ZAU ARTCC RADAR CTLR LOST SEPARATION DURING OVERTAKE INCIDENT.

Narrative: SAW OVERTAKE ON SLOWLY CONVERGING RTES. TURNED SLOWER, FRONT ACFT 30 DEGS TO L AND FASTER, BACK ACFT 10 DEGS R, TO CROSS BEFORE OVERTAKE MADE IT TOO LATE. IT LOOKED LIKE I'D HAVE 5 NM BARE SEPARATION. CONFLICT ALERT ACTIVATED, BUT WAS MORE OF A DISTR IN THIS CASE BECAUSE IT WAS A CTLED SIT AND THE LAG INHERENT IN CONFLICT ALERT MADE IT UNRELIABLE. THE RULES REQUIRE 5 NM SEPARATION. IF A CTLR USES 5 NM SEPARATION AND IS COMFORTABLE WITH IT, AS I HAVE DONE MY ENTIRE CAREER, THEN ON RARE OCCASIONS HE OR SHE WILL COME UP A LITTLE SHORT. THE SIT DID NOT COMPROMISE SAFETY IN ANY WAY. THE SYS WORKED IN THIS CASE. WE MISSED BY 5 NM BECAUSE WE ARE HUMAN AND HUMANS MAKE MISTAKES. THE 5 MI RULE IS THE BUFFER. I AM GLAD IT IS THERE. YOU CAN'T TELL A CTLR TO GO FOR MORE SEPARATION THAN REQUIRED AND YOU CAN'T LOWER THE BAR WHEN THE BUFFER IS BREACHED. TELL US THE STANDARD, I'LL MAKE IT HAPPEN. UNFORTUNATELY, I AM HUMAN, I DO MAKE MISTAKES. THE BENEFITS OF HAVING A HUMAN IN THE LOOP FAR AND AWAY OVERSHADOW THE SIMPLE NEGATIVE. IN MY 13 YRS AS A RADAR CTLR, I CAN'T GUESS HOW MANY TIMES I HAVE EFFECTIVELY HANDLED SITS ALL WITH 100% ACCURACY. I DON'T PLAN TO CHANGE THE WAY I WORK IN ANY WAY. I AM THE BEST AT WHAT I DO. ANY REAL ATC CTLR WORTH A NICKEL WOULD SAY THE SAME. THE SYS IS SAFE.

Data retrieved from NASA's ASRS site as of July 2007 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.