Narrative:

Moduc arrival to runway 30L clearance after burke; turn to 320 degree, slow to 210 K, descend to 8000'. Clearance was repeated and executed. At about 8500' the first officer called out traffic at about 12:30 and a mi at our altitude. I asked approach control what altitude the aircraft was at and he said 8000'. I told him we were leveling at 8000'. He immediately turned us right to 020 degree and climbed us to 10000'. Subsequently he leveled us at 9000'. This was not a near miss. Supplemental information from acn 171061. During descent on the moduc arrival to stl (lambert field) we were given clearance to turn to 320 degree. Then to slow to 2N KTS and descend from 10000' to 8000'. We complied with the clearance. As we were descending through approximately 8500' I saw an small transport Y aircraft at 1-2 O'clock position approximately 2 mi ahead slightly lower than we were. I asked the captain to verify his altitude and ATC responded that he was at 8000'. ATC immediately had us climb and turn to a heading of 020 degree. Vectors later took us to lambert. Could it have been possible for both of us to have been given the same clearance? If so ATC should have allowed more space behind the small transport X aircraft.

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Original NASA ASRS Text

Title: MLG ON MODUC ARR OVERTOOK SMT AND HAD LESS THAN STANDARD SEPARATION.

Narrative: MODUC ARR TO RWY 30L CLRNC AFTER BURKE; TURN TO 320 DEG, SLOW TO 210 K, DSND TO 8000'. CLRNC WAS REPEATED AND EXECUTED. AT ABOUT 8500' THE F/O CALLED OUT TFC AT ABOUT 12:30 AND A MI AT OUR ALT. I ASKED APCH CTL WHAT ALT THE ACFT WAS AT AND HE SAID 8000'. I TOLD HIM WE WERE LEVELING AT 8000'. HE IMMEDIATELY TURNED US R TO 020 DEG AND CLBED US TO 10000'. SUBSEQUENTLY HE LEVELED US AT 9000'. THIS WAS NOT A NEAR MISS. SUPPLEMENTAL INFO FROM ACN 171061. DURING DSNT ON THE MODUC ARR TO STL (LAMBERT FIELD) WE WERE GIVEN CLRNC TO TURN TO 320 DEG. THEN TO SLOW TO 2N KTS AND DSND FROM 10000' TO 8000'. WE COMPLIED WITH THE CLRNC. AS WE WERE DSNDING THROUGH APPROX 8500' I SAW AN SMT Y ACFT AT 1-2 O'CLOCK POS APPROX 2 MI AHEAD SLIGHTLY LOWER THAN WE WERE. I ASKED THE CAPT TO VERIFY HIS ALT AND ATC RESPONDED THAT HE WAS AT 8000'. ATC IMMEDIATELY HAD US CLB AND TURN TO A HDG OF 020 DEG. VECTORS LATER TOOK US TO LAMBERT. COULD IT HAVE BEEN POSSIBLE FOR BOTH OF US TO HAVE BEEN GIVEN THE SAME CLRNC? IF SO ATC SHOULD HAVE ALLOWED MORE SPACE BEHIND THE SMT X ACFT.

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.