Narrative:

Bmb X was northbound to whidbey NAS east of the sea 158 degree right which is the inbound route for jets landing at seattle from the south. Medium large transport Y was inbound on the sea 158 degree right from lax. Medium large transport Y was vectored west of the radial for sequencing. When sequencing was reestablished, medium large transport Y was vectored back to the right to reintercept the sea 158 degree radial. Bmb X had been converging slightly the whole time. When I realized that the medium large transport would not be below bmb X when the rtes crossed, I turned bmb X, but not in time to avoid loss of separation. I had believed bmb X had been on a jet route, when in fact he had been previously cleared direct which eventually placed him approximately 2 mi west of the airway when the error occurred.

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Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION WHEN A BMB AND MLG CONVERGE ON THE SAME ROUTE AT THE SAME ALT.

Narrative: BMB X WAS NBOUND TO WHIDBEY NAS EAST OF THE SEA 158 DEG RIGHT WHICH IS THE INBOUND RTE FOR JETS LNDG AT SEATTLE FROM THE SOUTH. MLG Y WAS INBOUND ON THE SEA 158 DEG RIGHT FROM LAX. MLG Y WAS VECTORED WEST OF THE RADIAL FOR SEQUENCING. WHEN SEQUENCING WAS REESTABLISHED, MLG Y WAS VECTORED BACK TO THE RIGHT TO REINTERCEPT THE SEA 158 DEG RADIAL. BMB X HAD BEEN CONVERGING SLIGHTLY THE WHOLE TIME. WHEN I REALIZED THAT THE MLG WOULD NOT BE BELOW BMB X WHEN THE RTES CROSSED, I TURNED BMB X, BUT NOT IN TIME TO AVOID LOSS OF SEPARATION. I HAD BELIEVED BMB X HAD BEEN ON A JET RTE, WHEN IN FACT HE HAD BEEN PREVIOUSLY CLRED DIRECT WHICH EVENTUALLY PLACED HIM APPROX 2 MI WEST OF THE AIRWAY WHEN THE ERROR OCCURRED.

Data retrieved from NASA's ASRS site as of August 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.