Narrative:

We were aircraft X from clt to lyh at 13000 ft. ZTL (134.55) called traffic in our 9 O'clock position. We acknowledged traffic in sight. Our flight was called to an aircraft (F100) and acknowledged in sight. ZTL cleared the air carrier flight to descend through our altitude maintaining visual separation. They accepted the clearance. The flight paths were converging and I noted to my first officer that this would be close. Within moments we had a TCASII alert for traffic and then a command to monitor vertical speed. A 1500 FPM descent was initiated. We leveled 1300 ft below assigned altitude with the clear of conflict notification as the jet passed 1000 ft directly overhead. While climbing back to our assigned altitude, ZTL asked about our altitude. I noted the deviation due to the TCASII alert. We were then handed over to the next sector as if nothing had occurred. I believe that the other flight lost sight of us or misjudged the closure rate.

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Original NASA ASRS Text

Title: A FOKKER 100 FLC WAS GIVEN A VISUAL SEPARATION RESTR TO A DSCNT CLRNC AND FAILED TO MAINTAIN SEPARATION FROM THE RPTING FLC.

Narrative: WE WERE ACFT X FROM CLT TO LYH AT 13000 FT. ZTL (134.55) CALLED TFC IN OUR 9 O'CLOCK POS. WE ACKNOWLEDGED TFC IN SIGHT. OUR FLT WAS CALLED TO AN ACFT (F100) AND ACKNOWLEDGED IN SIGHT. ZTL CLRED THE ACR FLT TO DSND THROUGH OUR ALT MAINTAINING VISUAL SEPARATION. THEY ACCEPTED THE CLRNC. THE FLT PATHS WERE CONVERGING AND I NOTED TO MY FO THAT THIS WOULD BE CLOSE. WITHIN MOMENTS WE HAD A TCASII ALERT FOR TFC AND THEN A COMMAND TO MONITOR VERT SPD. A 1500 FPM DSCNT WAS INITIATED. WE LEVELED 1300 FT BELOW ASSIGNED ALT WITH THE CLR OF CONFLICT NOTIFICATION AS THE JET PASSED 1000 FT DIRECTLY OVERHEAD. WHILE CLBING BACK TO OUR ASSIGNED ALT, ZTL ASKED ABOUT OUR ALT. I NOTED THE DEV DUE TO THE TCASII ALERT. WE WERE THEN HANDED OVER TO THE NEXT SECTOR AS IF NOTHING HAD OCCURRED. I BELIEVE THAT THE OTHER FLT LOST SIGHT OF US OR MISJUDGED THE CLOSURE RATE.

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.