POTENTIAL CONFLICT LTSS BTWN CLBING DSNDING TFC.

Narrative

CLRNC WAS FROM FL410 TO MAINTAIN FL260; CROSS 20 N OF OGD AT 17000 FT. THE LGT WAS EQUIPPED WITH TCASII AND IT WAS IN USE. TFC WAS OBSERVED APCHING NBOUND AT APPROX 30 NM RANGE ON THE TCASII. VISUAL SIGHTING AT APPROX 10 MI. WE CONTINUED DSCNT AND AT 28300 FT; ATC CALLED AND ADVISED TO 'MAINTAIN FL290'. AT ABOUT THIS TIME THE 'TFC' CALL WAS ISSUED FROM THE TCASII (NO RA). THE ACFT CLBING OUT PASSED OFF OUR R WING AT AN ESTIMATED 2 MI LATERAL SEPARATION AND ALT OF 28500 FT. NO EVASIVE ACTION WAS NECESSARY. WE DID NOT CLB BACK TO FL290 AS THE TFC WAS JUST PASSING US AND THE CLRNC WAS OBVIOUSLY LATE IN COMING. ATC THEN CLRED US TO CONTINUE ON DOWN TO 17000 FT. I SUSPECT THIS INCIDENT VIOLATED ATC SEPARATION STANDARDS AND IN MY OPINION THE INSTRUCTION TO 'MAINTAIN FL290' WAS LATE IN COMING. I WAS NOT AWARE OF WHAT ALT THE NBOUND ACFT WAS CLRED TO. I DID NOT AT ANY TIME FEEL THAT THERE WAS ANY SIGNIFICANT THREAT TO SAFE OP SINCE THE TFC WAS IN SIGHT AT ALL TIMES AND WAS ALSO BEING OBSERVED ON THE TCASII. IF ANYTHING; THIS CERTAINLY REINFORCED MY BELIEF THAT TCASII IS ONE OF THE BEST SAFETY ENHANCING ITEMS TO BE PUT ON ACFT SINCE RADAR.