Narrative:

I was providing OJT to a radar trainee. 20 aircraft in sector. Occasional light chop/turbulence all altitudes. Sfo spacing requires 15 mi in trail. The trainee was vectoring 5 aircraft for spacing to sfo in southwest quadrant of the sector. D-side accepted handoff (crj) up to FL290. Trainee was compelled to climb this crj into the sector (FL300 and above) so issued FL310. Created potential conflict with a nwbound aircraft at FL300. I encouraged trainee to turn the aircraft at FL300 20 degrees left to avoid or accommodate the crj up to FL310. Trainee issued vectors to the sfo bound aircraft. From the southeast of oal VORTAC is a citation at FL340 destined to trk; routed J92 oal direct trk. Trainee issued descent clearance to FL300 to trk bound aircraft. I did not hear this clearance being issued. I was writing a note for later critique and also maintaining situational awareness with the aircraft on vectors for spacing; and the 1 aircraft on a vector for traffic. Then with disbelief I noticed a sebound (aircraft #1) over oal VORTAC at FL330 and aircraft #2 (citation) nwbound mode C indicating 338 with assigned altitude of FL300. These 2 aircraft are nearly 12-14 mi apart (nose to nose) opposite direction. I issued a 60 degree left turn to aircraft #2 and clearance to maintain present altitude. #2 responded unable to maintain altitude (significantly reduced descent rate; however). Then; I issued 40 degree left turn with expeditious descent to FL300 to aircraft #1. 40 degrees due to tonopah test range to the east. Should have used 'immediately' versus 'expedite.' #2 appeared to level at FL334; I requested #1 to report leaving FL324 (separation) and #1 responded leaving FL321 (as #1 and #2 were 5 mi lateral and decreasing) and leveling at FL300. Conflict alert did activate; then; automatically extinguished. Separation was maintained. Aircraft #1 reported traffic no factor. I believe #2 could not stop descent perhaps due to an RA (TCAS) (#2 did not advise of RA) and #1 may have initiated an RA descent as I was issuing descent clearance. I was perhaps lucky that both aircraft got their clrncs versus blocked due to radio congestion. Aircraft also responded quickly.

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Original NASA ASRS Text

Title: ZOA CTLR PROVIDING OJT; EXPERIENCED NEAR LOSS OF SEPARATION AT APPROX FL320 WITH OPPOSITE DIR TFC; CITING OJT NOTE TAKING AS CONTRIBUTORY.

Narrative: I WAS PROVIDING OJT TO A RADAR TRAINEE. 20 ACFT IN SECTOR. OCCASIONAL LIGHT CHOP/TURB ALL ALTS. SFO SPACING REQUIRES 15 MI IN TRAIL. THE TRAINEE WAS VECTORING 5 ACFT FOR SPACING TO SFO IN SW QUADRANT OF THE SECTOR. D-SIDE ACCEPTED HDOF (CRJ) UP TO FL290. TRAINEE WAS COMPELLED TO CLB THIS CRJ INTO THE SECTOR (FL300 AND ABOVE) SO ISSUED FL310. CREATED POTENTIAL CONFLICT WITH A NWBOUND ACFT AT FL300. I ENCOURAGED TRAINEE TO TURN THE ACFT AT FL300 20 DEGS L TO AVOID OR ACCOMMODATE THE CRJ UP TO FL310. TRAINEE ISSUED VECTORS TO THE SFO BOUND ACFT. FROM THE SE OF OAL VORTAC IS A CITATION AT FL340 DESTINED TO TRK; ROUTED J92 OAL DIRECT TRK. TRAINEE ISSUED DSCNT CLRNC TO FL300 TO TRK BOUND ACFT. I DID NOT HEAR THIS CLRNC BEING ISSUED. I WAS WRITING A NOTE FOR LATER CRITIQUE AND ALSO MAINTAINING SITUATIONAL AWARENESS WITH THE ACFT ON VECTORS FOR SPACING; AND THE 1 ACFT ON A VECTOR FOR TFC. THEN WITH DISBELIEF I NOTICED A SEBOUND (ACFT #1) OVER OAL VORTAC AT FL330 AND ACFT #2 (CITATION) NWBOUND MODE C INDICATING 338 WITH ASSIGNED ALT OF FL300. THESE 2 ACFT ARE NEARLY 12-14 MI APART (NOSE TO NOSE) OPPOSITE DIRECTION. I ISSUED A 60 DEG L TURN TO ACFT #2 AND CLRNC TO MAINTAIN PRESENT ALT. #2 RESPONDED UNABLE TO MAINTAIN ALT (SIGNIFICANTLY REDUCED DSCNT RATE; HOWEVER). THEN; I ISSUED 40 DEG L TURN WITH EXPEDITIOUS DSCNT TO FL300 TO ACFT #1. 40 DEGS DUE TO TONOPAH TEST RANGE TO THE E. SHOULD HAVE USED 'IMMEDIATELY' VERSUS 'EXPEDITE.' #2 APPEARED TO LEVEL AT FL334; I REQUESTED #1 TO RPT LEAVING FL324 (SEPARATION) AND #1 RESPONDED LEAVING FL321 (AS #1 AND #2 WERE 5 MI LATERAL AND DECREASING) AND LEVELING AT FL300. CONFLICT ALERT DID ACTIVATE; THEN; AUTOMATICALLY EXTINGUISHED. SEPARATION WAS MAINTAINED. ACFT #1 RPTED TFC NO FACTOR. I BELIEVE #2 COULD NOT STOP DSCNT PERHAPS DUE TO AN RA (TCAS) (#2 DID NOT ADVISE OF RA) AND #1 MAY HAVE INITIATED AN RA DSCNT AS I WAS ISSUING DSCNT CLRNC. I WAS PERHAPS LUCKY THAT BOTH ACFT GOT THEIR CLRNCS VERSUS BLOCKED DUE TO RADIO CONGESTION. ACFT ALSO RESPONDED QUICKLY.

Data retrieved from NASA's ASRS site as of January 2009 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.