Narrative:

The skylane was maneuvering in the class C outer area, receiving TA's on my frequency. He had been mostly at 5000 ft, but west of the arrival corridor where the sna jet arrs transition at 5000 ft. When the B737 showed up, I noticed the skylane had turned eastbound, putting him on a converging course with the B737. I asked the skylane if he was continuing that direction. He replied that he was. I instructed the pilot to either reverse course, or climb to 5500 ft for traffic. There was no response. I issued the traffic to the B737 (approximately 4 mi away). The pilot replied that he was looking. I called traffic to the skylane and instructed the pilot to climb -- there was no response. I issued traffic to the B737 again, and advised him the other aircraft was not listening. The pilot of the B737 did not see the aircraft. As my airspace lower limit is 5000 ft, I quickly coordinated with the adjacent sector, issued the B737 a traffic alert, and descended him to 4000 ft. The aircraft passed within 1/2 mi laterally and approximately 300 ft vertically. When I finally regained radio communication with the skylane he apologized for not hearing my calls. A controller's only tool is a frequency. If aircraft are not listening to their radios, it is impossible for us to do our jobs.

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Original NASA ASRS Text

Title: SCT CTLR TAKES INITIATIVE WHEN PERCEIVING POTENTIAL CONFLICT BTWN A VFR C182 AND B737 ON APCH TO SNA.

Narrative: THE SKYLANE WAS MANEUVERING IN THE CLASS C OUTER AREA, RECEIVING TA'S ON MY FREQ. HE HAD BEEN MOSTLY AT 5000 FT, BUT W OF THE ARR CORRIDOR WHERE THE SNA JET ARRS TRANSITION AT 5000 FT. WHEN THE B737 SHOWED UP, I NOTICED THE SKYLANE HAD TURNED EBOUND, PUTTING HIM ON A CONVERGING COURSE WITH THE B737. I ASKED THE SKYLANE IF HE WAS CONTINUING THAT DIRECTION. HE REPLIED THAT HE WAS. I INSTRUCTED THE PLT TO EITHER REVERSE COURSE, OR CLB TO 5500 FT FOR TFC. THERE WAS NO RESPONSE. I ISSUED THE TFC TO THE B737 (APPROX 4 MI AWAY). THE PLT REPLIED THAT HE WAS LOOKING. I CALLED TFC TO THE SKYLANE AND INSTRUCTED THE PLT TO CLB -- THERE WAS NO RESPONSE. I ISSUED TFC TO THE B737 AGAIN, AND ADVISED HIM THE OTHER ACFT WAS NOT LISTENING. THE PLT OF THE B737 DID NOT SEE THE ACFT. AS MY AIRSPACE LOWER LIMIT IS 5000 FT, I QUICKLY COORDINATED WITH THE ADJACENT SECTOR, ISSUED THE B737 A TFC ALERT, AND DSNDED HIM TO 4000 FT. THE ACFT PASSED WITHIN 1/2 MI LATERALLY AND APPROX 300 FT VERTLY. WHEN I FINALLY REGAINED RADIO COM WITH THE SKYLANE HE APOLOGIZED FOR NOT HEARING MY CALLS. A CTLR'S ONLY TOOL IS A FREQ. IF ACFT ARE NOT LISTENING TO THEIR RADIOS, IT IS IMPOSSIBLE FOR US TO DO OUR JOBS.

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.