Narrative:

A trainee and I, on whom I was conducting an OJT evaluation, assumed the ar-5, south feeder position at bay approach. Air carrier X sfo arrival from over pye, was assigned direct sfo, depart the VOR heading 140 degrees to maintain 11000 ft. Speed had been reduced to 210 KTS by the previous controller. Air carrier Y sjc arrival also from over pye, was assigned the same route at 12000 ft, not slowed. Air carrier Y was positioned behind air carrier X and closing due to the airspeed difference. When air carrier X reached sfo, air carrier Y was 1-2 mi behind. After air carrier Y crossed sfo, the trainee issued the flight descent to 9000 ft. At the time of this transmission, I was making a notation regarding the evaluation in progress. I heard the altitude but was not sure of the call sign used. There were approximately 5 or 6 other aircraft on frequency at the time, and I mistakenly thought the descent was for one of them. When I looked to make sure who was given the descent, we realized what had happened. Air carrier X was then turned right to 180 degrees, air carrier Y left to 090 degrees. Air carrier Y stated that he had the traffic in sight.

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Original NASA ASRS Text

Title: CTLR TRAINING IN PROGRESS ACR Y DSCNT TO OCCUPIED ALT HAD LTSS FROM ACR X. SYS ERROR.

Narrative: A TRAINEE AND I, ON WHOM I WAS CONDUCTING AN OJT EVALUATION, ASSUMED THE AR-5, S FEEDER POS AT BAY APCH. ACR X SFO ARR FROM OVER PYE, WAS ASSIGNED DIRECT SFO, DEPART THE VOR HDG 140 DEGS TO MAINTAIN 11000 FT. SPD HAD BEEN REDUCED TO 210 KTS BY THE PREVIOUS CTLR. ACR Y SJC ARR ALSO FROM OVER PYE, WAS ASSIGNED THE SAME RTE AT 12000 FT, NOT SLOWED. ACR Y WAS POSITIONED BEHIND ACR X AND CLOSING DUE TO THE AIRSPD DIFFERENCE. WHEN ACR X REACHED SFO, ACR Y WAS 1-2 MI BEHIND. AFTER ACR Y CROSSED SFO, THE TRAINEE ISSUED THE FLT DSCNT TO 9000 FT. AT THE TIME OF THIS XMISSION, I WAS MAKING A NOTATION REGARDING THE EVALUATION IN PROGRESS. I HEARD THE ALT BUT WAS NOT SURE OF THE CALL SIGN USED. THERE WERE APPROX 5 OR 6 OTHER ACFT ON FREQ AT THE TIME, AND I MISTAKENLY THOUGHT THE DSCNT WAS FOR ONE OF THEM. WHEN I LOOKED TO MAKE SURE WHO WAS GIVEN THE DSCNT, WE REALIZED WHAT HAD HAPPENED. ACR X WAS THEN TURNED R TO 180 DEGS, ACR Y L TO 090 DEGS. ACR Y STATED THAT HE HAD THE TFC IN SIGHT.

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.