Date: 201406
Local time of day: 1201-1800
Location: ZLA.ARTCC, CA
Light: Daylight
Aircraft: Medium Transport; Low Wing; 2 Turboprop Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class E ZLA
ATC / advisory: Center ZLA; TRACON SBA
Second aircraft: Small Aircraft; Low Wing; 1 Eng; Retractable Gear
Reporter organization: Government
Reporter function: Enroute; Instructor
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Distraction; Communication Breakdown; Troubleshooting
Second reporter function: Enroute
Anomaly: ATC Issue All Types; Conflict Airborne Conflict
Detector: Automation Aircraft RA
Result: Flight Crew Took Evasive Action
Contributing factors: Airspace Structure; Equipment / Tooling; Procedure
Primary problem: Equipment / Tooling

Narrative: The biggest contributing factor is the scheduled QLA radar outage that is happening all this week.  We get countless handoffs from SBA Approach every day.  Usually; we get primary and secondary radar coverage below 040; but with QLA OTS; most of the targets are appearing between 070 and 090.  Aircraft X was level at 100 direct KWANG.  SBA Approach called and said there was a VFR they were attempting to hand off to us. They described him as a slow climber; south east bound; climbing out of 055 for 095 VFR.  We told him that we wouldn't pick him up for a while; but we would call when we had radar.  Then; we coordinated Aircraft X at 100; and gave SBA control; as we didn't want to descend Aircraft X through the VFR's cruise altitude.As the trainer; while I discussed the merits of this plan with my trainee; I didn't actually expect the VFR to reach 095 before being past Aircraft X; and I certainly didn't expect Aircraft Y to reach 095 before we were able to pick up a target.  SBA took back the flash and coordinated that they had handed off and shipped the VFR to NTD Approach as we still were unable to pick up a target. No altitude was coordinated at that time. We should have asked for an updated Mode C at that time. Aircraft X asked us is a garbled sentence if we saw that traffic; then cut his sentence short and said never mind; we have him in sight.  I asked if there was an aircraft out there; because we were having a radar issue and we were picking up most targets around 080 to 090; but we didn't see any targets near his.He responded that there was an aircraft on his TCAS at 096 and that he had received an RA.  I acknowledged; and ensured that any maneuver was complete and that he was level at 100 before we shipped him to SBA.  Some time during that back and forth; we observed a code pop up 6 miles south of Aircraft X's current position; Mode C 045.  An update later; it jumped to directly behind Aircraft X; Mode C 095.  Flight plan readout on the code showed that is was the VFR from SBA.  Several updates later; a data block correlated with the target. Recommend some interim procedure or equipment procedure to minimize the effect on active traffic when a major radar site needs maintenance.  The current practice of constantly calling for attitude checks (as we lose Mode C and primary data before most aircraft descend out of our airspace); hand offs leveling off; and calls for higher put an undue stress on Sector 14; SBA and NTD; especially since this was a scheduled outage and these issues could have been foreseen.


Second narrative: At Sector 14 we received a call from SBA Approach asking us if we had a target on Aircraft Y; a VFR climbing out of SBA Approach's airspace.  We did not have a target because of a QLA radar outage.  SBA said that he was leaving 055 MSL and asked if we wanted them to terminate him or just hand him off to NTD Approach.  We said either hand him off to NTD or hold onto him and we would take radar when we got a target on him (throughout the day; in that area; we had been getting radar on aircraft in the vicinity of 070 MSL); however; we weren't getting a target on him.  So we APPREQ'd Aircraft X at 100 MSL and SBA's control because we knew that Aircraft Y's eventual request was VFR/095 and we didn't want to descend Aircraft X through his altitude without a good target on Aircraft Y (SBA had radar; so we figured they were the best ones to work Aircraft X).  SBA did not tell us of Aircraft Y's position or altitude with respect to Aircraft X or that they would even be a factor.  So; before we were able to ship Aircraft X; he called up with a different call sign and asked if there was traffic.  We then asked the position of the aircraft because of the different call sign and he said 'traffic in sight' and then gave his position.  We verified that his call sign was Aircraft X and he responded with affirmative and said he responded to an RA with an aircraft at 096 MSL that we had no target for. Oddly; there was a target that displayed at 045 MSL just after he said he responded to the RA and then on the next update showed at 096 MSL; roughly 2 miles past Aircraft X. This target ended up being Aircraft Y. The QLA radar outage creates and unsafe situation where we may not see aircraft/targets until they're well into our airspace and a factor for aircraft we are working and would normally be able to call traffic for. This radar outage is scheduled to last 10 days; it seems like a very long time to have the potential for these types of situations.


Synopsis: ZLA controllers describe situation where the primary radar system for one area is released to maintenance when an aircraft responds to an RA in which they did not have a target on.