Narrative:

This incident occurred approximately 15 mi north of sna. The WX was 1900 ft overcast. The ILS approach was in use. The arrival rate was high. I was working the sna arrival sector. I did not have a handoff/assistant plugged in due to staffing issues. These are the following complications of working the sna arrival sector: 1) high terrain to the east. The MVA's make it difficult to get the aircraft down in a timely enough manner to turn them onto the final from the east; instead of taking them across and putting them on a right downwind. And; you really cannot use this airspace to the east below 5000 ft. 2) there are essentially only 3 usable IFR altitudes (3000 ft; 4000 ft; and 5000 ft). On the right downwind; if your traffic is not situated exactly 3 mi west of the final and 1.5 mi from the adjacent sector to the west; you will have an operational error. When the sector is busy it is challenging to keep all aircraft 3 mi or 1000 ft apart (standard IFR separation). 3) the sector is extremely compact. It owns approximately 15 mi of airspace to the north; mainly due to the lax final. When the arrival rate is high; you have nowhere to put the aircraft. If the airport is advertising ILS approachs due to WX; now you are forced to mix all small aircraft with jet/turboprop aircraft and put them on your final. Wake turbulence separation increases the spacing on final. So; for example; the optimal final could hold no more than 5 aircraft. Inside the OM; we can go down to 2.5 NM separation between like aircraft; then 3 mi separation outside the OM. That is 5 like aircraft on the final; as long as they are all going the exact same speed; and there are no wake turbulence issues. Now; look at a scenario with a B757; and a PA28. The PA28 needs 5 mi minimum behind the B757. And obviously; if you have a C172 doing 100 KTS and 5 jets behind him; even slowed to the minimum speeds; you need at least 6-8 mi behind that C172; because of the closure rate. I am sure you get the point. 4) you have aircraft coming into the sector from every direction. The jet/turboprop aircraft come inbound over kayoh intersection from the east at 5200 ft and 190 KTS. Small aircraft from the southeast for sna at 5000 ft on a vector to the OM; or on a V363 route at 5000 ft transitioning the airspace. Jet/turboprop aircraft from the southwest on a right downwind at 5000 ft that should be doing 200 KTS because they are under class B airspace. All small aircraft departing sna to the north via V363; V8; V21; lhs; climbing northwest off the airport to 3000 ft. You need to get these aircraft up and on their way through your right downwind traffic that needs to descend. From west over sli landing sna at 4000 ft or via V8 routing at 5000 ft. Recipe for disaster; 5000 ft traffic is on converging courses; and aircraft east of sli drop off your scope for 30 seconds or more due to these aircraft flying into the radar antennae main bang. From the north you get jets inbound via V363 at 4000 ft and 210 KTS (if you're lucky) and they show up without warning; practically right on your final. Also; from the north you get small aircraft landing lgb; ful; and toa at 4000 ft heading south. You also get ful departures landing sna; going southeast and northeast climbing to 3000 ft. Now; let me describe the incident that occurred with aircraft X and a learjet inbound from the north on a V363 route at 4000 ft and 210 KTS. Aircraft X was on right downwind out of 5000 ft for 4000 ft. There was a BE90 doing east/west turns dropping flies at 3500 ft VFR; interfering with right downwind; right/left base and the final. Normally aircraft X would have been descended to 3000 ft; but had to stay at 4000 ft for the BE90. Pomona sector called me with a handoff from the north. I instructed the controller to have him fly heading 170 degrees and reduce speed 170 KTS. At the time of the instruction; the lear appeared to be on the prescribed handoff; which would be off the pom 164 degree radial. My plan was to extend aircraft X on downwind and put the lear on final ahead. I noticed the lear heading wbound; so I called pomona sector and pointed out aircraft X heading 360 degrees; and asked; 'is that lear turning?' and as I keyed up; the controller was saying to the lear; 'expedite turn.' at this point it became apparent that the lear was not on the correct route/heading. I called traffic to aircraft X; 1 O'clock position; 4 mi; turning sebound; 4000 ft. Pomona said I could descend the aircraft X to 3000 ft; so I started him down. Aircraft X got the lear in sight and I advised the pilot he would follow that traffic inbound to the airport and to maintain visual separation with that traffic. At the time I believed I had visual separation prior to losing standard separation. I am now second-guessing that and believe I may have not had it in time. This incident occurred because of a breakdown in communication between the controllers. BE90 was a distracter; and having a handoff there to coordination and a second set of eyes could have been very helpful. I had been on position for approximately 1 hour 15 mins; working moderate to heavy traffic with a high level of complexity. I am not telling this story to justify what happened; I am telling this story so that pilots may get a better understanding of what we are dealing with on the ATC side.

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Original NASA ASRS Text

Title: SCT CTLR DESCRIBES WORK ENVIRONMENT AND CLOSE SEPARATION ERROR AT 4000 FT.

Narrative: THIS INCIDENT OCCURRED APPROX 15 MI N OF SNA. THE WX WAS 1900 FT OVCST. THE ILS APCH WAS IN USE. THE ARR RATE WAS HIGH. I WAS WORKING THE SNA ARR SECTOR. I DID NOT HAVE A HDOF/ASSISTANT PLUGGED IN DUE TO STAFFING ISSUES. THESE ARE THE FOLLOWING COMPLICATIONS OF WORKING THE SNA ARR SECTOR: 1) HIGH TERRAIN TO THE E. THE MVA'S MAKE IT DIFFICULT TO GET THE ACFT DOWN IN A TIMELY ENOUGH MANNER TO TURN THEM ONTO THE FINAL FROM THE E; INSTEAD OF TAKING THEM ACROSS AND PUTTING THEM ON A R DOWNWIND. AND; YOU REALLY CANNOT USE THIS AIRSPACE TO THE E BELOW 5000 FT. 2) THERE ARE ESSENTIALLY ONLY 3 USABLE IFR ALTS (3000 FT; 4000 FT; AND 5000 FT). ON THE R DOWNWIND; IF YOUR TFC IS NOT SITUATED EXACTLY 3 MI W OF THE FINAL AND 1.5 MI FROM THE ADJACENT SECTOR TO THE W; YOU WILL HAVE AN OPERROR. WHEN THE SECTOR IS BUSY IT IS CHALLENGING TO KEEP ALL ACFT 3 MI OR 1000 FT APART (STANDARD IFR SEPARATION). 3) THE SECTOR IS EXTREMELY COMPACT. IT OWNS APPROX 15 MI OF AIRSPACE TO THE N; MAINLY DUE TO THE LAX FINAL. WHEN THE ARR RATE IS HIGH; YOU HAVE NOWHERE TO PUT THE ACFT. IF THE ARPT IS ADVERTISING ILS APCHS DUE TO WX; NOW YOU ARE FORCED TO MIX ALL SMALL ACFT WITH JET/TURBOPROP ACFT AND PUT THEM ON YOUR FINAL. WAKE TURB SEPARATION INCREASES THE SPACING ON FINAL. SO; FOR EXAMPLE; THE OPTIMAL FINAL COULD HOLD NO MORE THAN 5 ACFT. INSIDE THE OM; WE CAN GO DOWN TO 2.5 NM SEPARATION BTWN LIKE ACFT; THEN 3 MI SEPARATION OUTSIDE THE OM. THAT IS 5 LIKE ACFT ON THE FINAL; AS LONG AS THEY ARE ALL GOING THE EXACT SAME SPD; AND THERE ARE NO WAKE TURB ISSUES. NOW; LOOK AT A SCENARIO WITH A B757; AND A PA28. THE PA28 NEEDS 5 MI MINIMUM BEHIND THE B757. AND OBVIOUSLY; IF YOU HAVE A C172 DOING 100 KTS AND 5 JETS BEHIND HIM; EVEN SLOWED TO THE MINIMUM SPDS; YOU NEED AT LEAST 6-8 MI BEHIND THAT C172; BECAUSE OF THE CLOSURE RATE. I AM SURE YOU GET THE POINT. 4) YOU HAVE ACFT COMING INTO THE SECTOR FROM EVERY DIRECTION. THE JET/TURBOPROP ACFT COME INBOUND OVER KAYOH INTXN FROM THE E AT 5200 FT AND 190 KTS. SMALL ACFT FROM THE SE FOR SNA AT 5000 FT ON A VECTOR TO THE OM; OR ON A V363 RTE AT 5000 FT TRANSITIONING THE AIRSPACE. JET/TURBOPROP ACFT FROM THE SW ON A R DOWNWIND AT 5000 FT THAT SHOULD BE DOING 200 KTS BECAUSE THEY ARE UNDER CLASS B AIRSPACE. ALL SMALL ACFT DEPARTING SNA TO THE N VIA V363; V8; V21; LHS; CLBING NW OFF THE ARPT TO 3000 FT. YOU NEED TO GET THESE ACFT UP AND ON THEIR WAY THROUGH YOUR R DOWNWIND TFC THAT NEEDS TO DSND. FROM W OVER SLI LNDG SNA AT 4000 FT OR VIA V8 ROUTING AT 5000 FT. RECIPE FOR DISASTER; 5000 FT TFC IS ON CONVERGING COURSES; AND ACFT E OF SLI DROP OFF YOUR SCOPE FOR 30 SECONDS OR MORE DUE TO THESE ACFT FLYING INTO THE RADAR ANTENNAE MAIN BANG. FROM THE N YOU GET JETS INBOUND VIA V363 AT 4000 FT AND 210 KTS (IF YOU'RE LUCKY) AND THEY SHOW UP WITHOUT WARNING; PRACTICALLY RIGHT ON YOUR FINAL. ALSO; FROM THE N YOU GET SMALL ACFT LNDG LGB; FUL; AND TOA AT 4000 FT HDG S. YOU ALSO GET FUL DEPS LNDG SNA; GOING SE AND NE CLBING TO 3000 FT. NOW; LET ME DESCRIBE THE INCIDENT THAT OCCURRED WITH ACFT X AND A LEARJET INBOUND FROM THE N ON A V363 RTE AT 4000 FT AND 210 KTS. ACFT X WAS ON R DOWNWIND OUT OF 5000 FT FOR 4000 FT. THERE WAS A BE90 DOING E/W TURNS DROPPING FLIES AT 3500 FT VFR; INTERFERING WITH R DOWNWIND; R/L BASE AND THE FINAL. NORMALLY ACFT X WOULD HAVE BEEN DSNDED TO 3000 FT; BUT HAD TO STAY AT 4000 FT FOR THE BE90. POMONA SECTOR CALLED ME WITH A HDOF FROM THE N. I INSTRUCTED THE CTLR TO HAVE HIM FLY HDG 170 DEGS AND REDUCE SPD 170 KTS. AT THE TIME OF THE INSTRUCTION; THE LEAR APPEARED TO BE ON THE PRESCRIBED HDOF; WHICH WOULD BE OFF THE POM 164 DEG RADIAL. MY PLAN WAS TO EXTEND ACFT X ON DOWNWIND AND PUT THE LEAR ON FINAL AHEAD. I NOTICED THE LEAR HDG WBOUND; SO I CALLED POMONA SECTOR AND POINTED OUT ACFT X HDG 360 DEGS; AND ASKED; 'IS THAT LEAR TURNING?' AND AS I KEYED UP; THE CTLR WAS SAYING TO THE LEAR; 'EXPEDITE TURN.' AT THIS POINT IT BECAME APPARENT THAT THE LEAR WAS NOT ON THE CORRECT RTE/HDG. I CALLED TFC TO ACFT X; 1 O'CLOCK POS; 4 MI; TURNING SEBOUND; 4000 FT. POMONA SAID I COULD DSND THE ACFT X TO 3000 FT; SO I STARTED HIM DOWN. ACFT X GOT THE LEAR IN SIGHT AND I ADVISED THE PLT HE WOULD FOLLOW THAT TFC INBOUND TO THE ARPT AND TO MAINTAIN VISUAL SEPARATION WITH THAT TFC. AT THE TIME I BELIEVED I HAD VISUAL SEPARATION PRIOR TO LOSING STANDARD SEPARATION. I AM NOW SECOND-GUESSING THAT AND BELIEVE I MAY HAVE NOT HAD IT IN TIME. THIS INCIDENT OCCURRED BECAUSE OF A BREAKDOWN IN COM BTWN THE CTLRS. BE90 WAS A DISTRACTER; AND HAVING A HDOF THERE TO COORD AND A SECOND SET OF EYES COULD HAVE BEEN VERY HELPFUL. I HAD BEEN ON POS FOR APPROX 1 HR 15 MINS; WORKING MODERATE TO HVY TFC WITH A HIGH LEVEL OF COMPLEXITY. I AM NOT TELLING THIS STORY TO JUSTIFY WHAT HAPPENED; I AM TELLING THIS STORY SO THAT PLTS MAY GET A BETTER UNDERSTANDING OF WHAT WE ARE DEALING WITH ON THE ATC SIDE.

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.