Narrative:

A near midair occurred at sector 19, los angeles ARTCC on dec/xx/91 at approximately XA05 hours local. I was the radar controller in charge. The sector was one holed with moderate or greater level of complexity at the time. Air carrier X was an light transport that departed ontario en route to bullhead city, az. The aircraft checked in at 11000 ft. I had traffic inbound opposite direction at 12000 and informed the pilot that there would be a delay in his climb. After the aircraft cleared each other I issued climb clearance to air carrier X to 14000 ft. I had additional traffic inbound that I descended to 15000 as per LOA with ontario approach. This was to try to expedite both pieces of traffic. Air carrier X acknowledged his climb clearance and I issued a TA on the descending traffic and to expect further climb when clear. Shortly after this, air carrier X asked what just passed over him. Scanning the scope, I did not see anything and asked the pilot to say again. The pilot said he wanted to know what the traffic was that just passed over him. I said that I did not have any traffic and then saw a VFR target at 12500. I informed the pilot of what I saw and he responded that the aircraft had missed by about 50 ft. Air carrier X was clear of the IFR traffic now and I issued climb to his requested altitude of 17000 ft. The aircraft was frequency change to sector 17 and then I informed the supervisor of incident. At the time of the occurrence I was working several aircraft to los angeles that required sequencing, numerous aircraft inbound to the ontario complex, many of which required coordination with other sectors and just before the situation I was monitoring a potential operational error between an aircraft that I had frequency change to ontario approach and a los angeles arrival on the civet 2 profile descent. I did alert the supervisor to this situation also. Also there were several data blocks in the vicinity of air carrier X. During my transmissions to air carrier X I did on a couple of occasions call the aircraft wrong identify. This didn't seem to create a communication problem since the pilot caught it each time. After landing the pilot did call in to the area and talked to the controller in charge. He informed the controller in charge that if he hadn't looked up when he did that they would all be dead. He also stated that he felt that under IFR radar service he should be afforded TA's that allow him to keep his attention inside the cockpit. He also requested my name, but that was refused. The pilot then talked to the area manager and then to quality assurance the next day. The following day I received a call at home from a quality assurance specialist. He said the pilot called in and that he was irate. Quality assurance needed to know the altitude limits set at the sector (000b242)?, what I thought my workload was (moderate or greater, I was busy), if I had a d-side (no) and did I request help (no). I was asked to come to the quality assurance office to write a statement before work that day. When I went up I was shown the ntap on the data from the sector that night. It showed a track swbound at 135 that descended to 133 ft. Then the mode C readout indicated 305 for about 3 updates. The dart showed that I never received an mci alert on this target. The automation department was certain that I did not receive an alert and that I did not have the target displayed on my scope, this was probable due to the altitude limits set at the sector. The VFR target was tracked and worked by ontario approach. It was idented as an aircraft with call sign X or Y. On the following mon morning a query will be run to determine the number of aircraft that I was working at the time. Due to the area of the country that I work in and that I work aircraft inbound to los angeles in an area that has numerous VFR aircraft crossing the los angeles localizer, watching, calling traffic and even assisting with radar vectors away from traffic is a normal situation in my work environment. But I don't see any way, that I can call traffic or issue advisories on traffic that isn't displayed to me.

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Original NASA ASRS Text

Title: ACR X HAD NMAC WITH MLT IN VMC CONDITIONS. EVASIVE ACTION TAKEN. SEE AND AVOID CONCEPT.

Narrative: A NEAR MIDAIR OCCURRED AT SECTOR 19, LOS ANGELES ARTCC ON DEC/XX/91 AT APPROX XA05 HRS LCL. I WAS THE RADAR CTLR IN CHARGE. THE SECTOR WAS ONE HOLED WITH MODERATE OR GREATER LEVEL OF COMPLEXITY AT THE TIME. ACR X WAS AN LTT THAT DEPARTED ONTARIO ENRTE TO BULLHEAD CITY, AZ. THE ACFT CHKED IN AT 11000 FT. I HAD TFC INBOUND OPPOSITE DIRECTION AT 12000 AND INFORMED THE PLT THAT THERE WOULD BE A DELAY IN HIS CLB. AFTER THE ACFT CLRED EACH OTHER I ISSUED CLB CLRNC TO ACR X TO 14000 FT. I HAD ADDITIONAL TFC INBOUND THAT I DSNDED TO 15000 AS PER LOA WITH ONTARIO APCH. THIS WAS TO TRY TO EXPEDITE BOTH PIECES OF TFC. ACR X ACKNOWLEDGED HIS CLB CLRNC AND I ISSUED A TA ON THE DSNDING TFC AND TO EXPECT FURTHER CLB WHEN CLR. SHORTLY AFTER THIS, ACR X ASKED WHAT JUST PASSED OVER HIM. SCANNING THE SCOPE, I DID NOT SEE ANYTHING AND ASKED THE PLT TO SAY AGAIN. THE PLT SAID HE WANTED TO KNOW WHAT THE TFC WAS THAT JUST PASSED OVER HIM. I SAID THAT I DID NOT HAVE ANY TFC AND THEN SAW A VFR TARGET AT 12500. I INFORMED THE PLT OF WHAT I SAW AND HE RESPONDED THAT THE ACFT HAD MISSED BY ABOUT 50 FT. ACR X WAS CLR OF THE IFR TFC NOW AND I ISSUED CLB TO HIS REQUESTED ALT OF 17000 FT. THE ACFT WAS FREQ CHANGE TO SECTOR 17 AND THEN I INFORMED THE SUPVR OF INCIDENT. AT THE TIME OF THE OCCURRENCE I WAS WORKING SEVERAL ACFT TO LOS ANGELES THAT REQUIRED SEQUENCING, NUMEROUS ACFT INBOUND TO THE ONTARIO COMPLEX, MANY OF WHICH REQUIRED COORD WITH OTHER SECTORS AND JUST BEFORE THE SITUATION I WAS MONITORING A POTENTIAL OPERROR BTWN AN ACFT THAT I HAD FREQ CHANGE TO ONTARIO APCH AND A LOS ANGELES ARR ON THE CIVET 2 PROFILE DSCNT. I DID ALERT THE SUPVR TO THIS SITUATION ALSO. ALSO THERE WERE SEVERAL DATA BLOCKS IN THE VICINITY OF ACR X. DURING MY TRANSMISSIONS TO ACR X I DID ON A COUPLE OF OCCASIONS CALL THE ACFT WRONG IDENT. THIS DIDN'T SEEM TO CREATE A COM PROBLEM SINCE THE PLT CAUGHT IT EACH TIME. AFTER LNDG THE PLT DID CALL IN TO THE AREA AND TALKED TO THE CTLR IN CHARGE. HE INFORMED THE CTLR IN CHARGE THAT IF HE HADN'T LOOKED UP WHEN HE DID THAT THEY WOULD ALL BE DEAD. HE ALSO STATED THAT HE FELT THAT UNDER IFR RADAR SVC HE SHOULD BE AFFORDED TA'S THAT ALLOW HIM TO KEEP HIS ATTN INSIDE THE COCKPIT. HE ALSO REQUESTED MY NAME, BUT THAT WAS REFUSED. THE PLT THEN TALKED TO THE AREA MGR AND THEN TO QUALITY ASSURANCE THE NEXT DAY. THE FOLLOWING DAY I RECEIVED A CALL AT HOME FROM A QUALITY ASSURANCE SPECIALIST. HE SAID THE PLT CALLED IN AND THAT HE WAS IRATE. QUALITY ASSURANCE NEEDED TO KNOW THE ALT LIMITS SET AT THE SECTOR (000B242)?, WHAT I THOUGHT MY WORKLOAD WAS (MODERATE OR GREATER, I WAS BUSY), IF I HAD A D-SIDE (NO) AND DID I REQUEST HELP (NO). I WAS ASKED TO COME TO THE QUALITY ASSURANCE OFFICE TO WRITE A STATEMENT BEFORE WORK THAT DAY. WHEN I WENT UP I WAS SHOWN THE NTAP ON THE DATA FROM THE SECTOR THAT NIGHT. IT SHOWED A TRACK SWBOUND AT 135 THAT DSNDED TO 133 FT. THEN THE MODE C READOUT INDICATED 305 FOR ABOUT 3 UPDATES. THE DART SHOWED THAT I NEVER RECEIVED AN MCI ALERT ON THIS TARGET. THE AUTOMATION DEPT WAS CERTAIN THAT I DID NOT RECEIVE AN ALERT AND THAT I DID NOT HAVE THE TARGET DISPLAYED ON MY SCOPE, THIS WAS PROBABLE DUE TO THE ALT LIMITS SET AT THE SECTOR. THE VFR TARGET WAS TRACKED AND WORKED BY ONTARIO APCH. IT WAS IDENTED AS AN ACFT WITH CALL SIGN X OR Y. ON THE FOLLOWING MON MORNING A QUERY WILL BE RUN TO DETERMINE THE NUMBER OF ACFT THAT I WAS WORKING AT THE TIME. DUE TO THE AREA OF THE COUNTRY THAT I WORK IN AND THAT I WORK ACFT INBOUND TO LOS ANGELES IN AN AREA THAT HAS NUMEROUS VFR ACFT XING THE LOS ANGELES LOC, WATCHING, CALLING TFC AND EVEN ASSISTING WITH RADAR VECTORS AWAY FROM TFC IS A NORMAL SITUATION IN MY WORK ENVIRONMENT. BUT I DON'T SEE ANY WAY, THAT I CAN CALL TFC OR ISSUE ADVISORIES ON TFC THAT ISN'T DISPLAYED TO ME.

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.