Narrative:

I was working local control position. Runway 11L/right in use. Marginal VFR conditions with 5 miles visibility and a ceiling of 3;000 ft beginning to deteriorate with incoming rain. Prior to any aircraft on frequency; nct supervisor requested an opposite direction approach with a circle to land runway 11 for aircraft X; which I approved. Despite having read the new briefing on opposite direction; I mistook circling to land on the advertised runway as a same direction arrival; which ultimately led to the following errors: aircraft Z was on final for runway 11L; cleared for the option and given left closed VFR traffic on the go. Aircraft X was approximately 8-9 mile final. I called for release on aircraft west; with a flow time. I received the release; reference aircraft X. I believed this to mean to ensure visual separation; which was covered under the old rules; but not under the new opposite direction rules. Weather conditions were continuing to deteriorate. I cleared aircraft west for take off of runway 11L after aircraft Z started his left crosswind; with aircraft Y on approximately 2-3 mile final runway 11L; cleared for the option with a left turn heading 050 on the go. Aircraft west began his right turn to a 200 heading with aircraft X approximately 4.5 mile final for runway 29R circle runway 11L; aircraft Y crossed the threshold; and began take off roll. Aircraft Y lifted up with aircraft X still on final for 29R circle 11L; aircraft X was instructed to circle south of the field. I began aircraft Y's left turn while aircraft X continued inbound. Aircraft X circled south as instructed. I believe had I read the briefing again after becoming unsure of whether a circling aircraft on an opposite direction approach was considered an opposite direction arrival; and broken off aircraft X on initial call or called nct to have them break of aircraft X sooner; this situation would have been averted.

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Original NASA ASRS Text

Title: SCK Controller experienced a loss of legal separation with regard to the new 'Opposite Direction Procedure' with a departing aircraft and another on a 'Circling Approach'; the reporter not realizing the new directive applied to this event.

Narrative: I was working Local Control position. Runway 11L/R in use. Marginal VFR conditions with 5 miles visibility and a ceiling of 3;000 FT beginning to deteriorate with incoming rain. Prior to any aircraft on frequency; NCT Supervisor requested an opposite direction approach with a circle to land Runway 11 for Aircraft X; which I approved. Despite having read the new briefing on Opposite Direction; I mistook circling to land on the advertised runway as a same direction arrival; which ultimately led to the following errors: Aircraft Z was on final for Runway 11L; cleared for the option and given left closed VFR traffic on the go. Aircraft X was approximately 8-9 mile final. I called for release on Aircraft W; with a flow time. I received the release; reference Aircraft X. I believed this to mean to ensure visual separation; which was covered under the old rules; but not under the new opposite direction rules. Weather conditions were continuing to deteriorate. I cleared Aircraft W for take off of Runway 11L after Aircraft Z started his left crosswind; with Aircraft Y on approximately 2-3 mile final Runway 11L; cleared for the option with a left turn heading 050 on the go. Aircraft W began his right turn to a 200 heading with Aircraft X approximately 4.5 mile final for Runway 29R circle Runway 11L; Aircraft Y crossed the threshold; and began take off roll. Aircraft Y lifted up with Aircraft X still on final for 29R circle 11L; Aircraft X was instructed to circle south of the field. I began Aircraft Y's left turn while Aircraft X continued inbound. Aircraft X circled south as instructed. I believe had I read the briefing again after becoming unsure of whether a circling aircraft on an opposite direction approach was considered an opposite direction arrival; and broken off Aircraft X on initial call or called NCT to have them break of Aircraft X sooner; this situation would have been averted.

Data retrieved from NASA's ASRS site as of July 2013 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.