Narrative:

I released aircraft X off of lgb runway 30. By the time lgb tower departed the aircraft; there was a VFR aircraft within their class D tracking south towards the departure corridor at 1;700 feet. When aircraft X became airborne I reached out to him when I didn't get an immediate check-in. That is when aircraft X checked in and I issued an expedited climb since he was converging the VFR target at 1;700 feet. When I noticed the VFR aircraft altitude appear to climb to 1;800 feet; I issued a 250 heading to aircraft X to get him away from the unverified target. After aircraft X was a safe proximity away from the VFR traffic; I asked him if lgb tower had told him about the traffic. He said they had and that they were told the traffic was going to go behind him. I explained to him that this wasn't the case because they were in-fact converging.this is a common occurrence with lgb tower. We will release an aircraft from lgb; which at the time the airspace is clean. By the time the aircraft gets airborne; there's usually a conflict to which we have to take evasive action to miss. This is because the tower just gives a traffic advisory; clears the aircraft for departure; and then issue a frequency change without ensuring separation. My recommendations is to retrain lgb tower on how to ensure separation of aircraft in their class D and decrease the amount of time lgb has to depart aircraft (I think right now they have a 4 minute window).

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Original NASA ASRS Text

Title: SCT TRACON Controller reported an NMAC with an IFR departure off of Long Beach and a VFR aircraft within the LGB Class Delta airspace.

Narrative: I released Aircraft X off of LGB Runway 30. By the time LGB tower departed the aircraft; there was a VFR aircraft within their Class D tracking south towards the departure corridor at 1;700 feet. When Aircraft X became airborne I reached out to him when I didn't get an immediate check-in. That is when Aircraft X checked in and I issued an expedited climb since he was converging the VFR target at 1;700 feet. When I noticed the VFR aircraft altitude appear to climb to 1;800 feet; I issued a 250 heading to Aircraft X to get him away from the unverified target. After Aircraft X was a safe proximity away from the VFR traffic; I asked him if LGB Tower had told him about the traffic. He said they had and that they were told the traffic was going to go behind him. I explained to him that this wasn't the case because they were in-fact converging.This is a common occurrence with LGB Tower. We will release an aircraft from LGB; which at the time the airspace is clean. By the time the aircraft gets airborne; there's usually a conflict to which we have to take evasive action to miss. This is because the Tower just gives a traffic advisory; clears the aircraft for departure; and then issue a frequency change without ensuring separation. My recommendations is to retrain LGB Tower on how to ensure separation of aircraft in their Class D and decrease the amount of time LGB has to depart aircraft (I think right now they have a 4 minute window).

Data retrieved from NASA's ASRS site 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.