An sct controller described possible conflict event after failing to insure visual approach clearanc...

Narrative:

Aircraft X was cleared for the visual approach to myf airport. It's possible that I didn't clear him or that he didn't read back the clearance. I transferred communication to myf tower when he was approximately twelve miles from the airport. Air carrier Y was cleared for the localizer runway 27 approach to san. I transferred communication to san tower when he was approximately twelve miles from the airport. Aircraft X went through the myf final; which put him on a converging course with air carrier Y. I noticed this and called myf tower and told them to immediately turn aircraft X to a 300 heading and maintain 4000. They did not do this. I don't know why. I called san tower and told them to turn air carrier Y immediately to 240 and maintain 4000. Their response was to ask me why. I told them for traffic. I called back myf tower; because I noticed that aircraft X wasn't turning. I told them again to turn him immediately. Approximately one minute after I told san tower to turn air carrier Y; air carrier Y started a turn to the southwest. Approximately two minutes after I told myf tower to turn aircraft X to the northwest; aircraft X started a turn. At this point; I believe they were still separated by three NM. Both towers said that they could 'barely hear me.' I'd had no such complaints that I can recall in at least the previous year. Recommendations: make sure I clear a guy for the visual and that he reads it back. Train tower controllers that when a radar controller instructs them to relay a control instruction to an IFR aircraft that time is of the essence; especially if the word 'immediately' is included in the instruction. Find out if there's a problem with the landlines or other equipment that would result in both towers able to only 'barely hear' me.

Original NASA ASRS Text

Title: An SCT controller described possible conflict event after failing to insure visual approach clearance was issued to a MYF arrival who flew through the final course and became traffic for a SAN air carrier arrival.

Narrative: Aircraft X was cleared for the visual approach to MYF airport. It's possible that I didn't clear him or that he didn't read back the clearance. I transferred communication to MYF Tower when he was approximately twelve miles from the airport. Air Carrier Y was cleared for the localizer Runway 27 approach to SAN. I transferred communication to SAN Tower when he was approximately twelve miles from the airport. Aircraft X went through the MYF final; which put him on a converging course with Air Carrier Y. I noticed this and called MYF Tower and told them to immediately turn Aircraft X to a 300 heading and maintain 4000. They did not do this. I don't know why. I called SAN Tower and told them to turn Air Carrier Y immediately to 240 and maintain 4000. Their response was to ask me why. I told them for traffic. I called back MYF Tower; because I noticed that Aircraft X wasn't turning. I told them again to turn him immediately. Approximately one minute after I told SAN Tower to turn Air Carrier Y; Air Carrier Y started a turn to the southwest. Approximately two minutes after I told MYF Tower to turn Aircraft X to the northwest; Aircraft X started a turn. At this point; I believe they were still separated by three NM. Both Towers said that they could 'barely hear me.' I'd had no such complaints that I can recall in at least the previous year. Recommendations: make sure I clear a guy for the visual and that he reads it back. Train Tower Controllers that when a RADAR Controller instructs them to relay a control instruction to an IFR aircraft that time is of the essence; especially if the word 'immediately' is included in the instruction. Find out if there's a problem with the landlines or other equipment that would result in both Towers able to only 'barely hear' me.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	879589
Time
Date	201003
Local Time Of Day	0001-0600
Place
Locale Reference	SCT.TRACON
State Reference	CA
Aircraft 1
Make Model Name	King Air 100 A/B
Flight Phase	Descent
Route In Use	Visual Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	Other Instrument Approach
Flight Plan	IFR
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Published Material / Policy

An sct controller described possible conflict event after failing to insure visual approach clearance was issued to a myf arrival who flew through the final course and became traffic for a san air carrier arrival.