Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 15
Communication Breakdown
ATC Issue All Types; Airspace Violation All Types; Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Air Traffic Control Separated Traffic; Flight Crew Returned To Clearance
Human Factors; Procedure
I had just relieved another controller and during the briefing I was told that Aircraft X was issued 9;000 feet which is the standard altitude that CASTA departures climb to.  I was also told that Aircraft X was in a vector for spacing with the CASTA departure in front of him; due to insufficient spacing provided by LAX Tower.  I was vectoring Aircraft X back to join the SID at the AJAYE intersection.  Aircraft Y was inbound to LAX at 10;000 feet.  I saw that aircraft and was trying to get Aircraft X in front of the Aircraft Y so he wouldn't be what I thought would be 1;000 feet below the super aircraft.  As I was vectoring the aircraft I observed a few hits at 9;000 feet which was the expected altitude for Aircraft X to be at.  As I cleared Aircraft X direct AJAYE I noticed his altitude was 10;000 feet; climbing.  I questioned Aircraft X and he told me that he was cleared to 13;000 feet.  He told me that he had the aircraft in sight and was continuing his climb.  I coordinated the altitude with the next sector since that was not the SOP altitude.  I then switched Aircraft X to the next controller.I don't know.  It was just a mistake by the controller during the briefing.
I was concerned about not get the spacing from the Tower I turned to the Supervisor to let them know.  As I was doing so I climbed the Aircraft X to 13;000 and it should have been 9;000.  I had a plan to build spacing so I gave the Aircraft X 13;000 and 230 knots.  My plan was to go runway heading so I accidentally gave him 13;000.  When he was reading back the altitude Tower buzzed in my ear so I didn't hear the read back.  I didn't know about the loss of separation between the two aircraft because I went on break.  When I brief my relief I told him Aircraft X was stopping at 9;000.  He turned the aircraft thinking the aircraft was going to stop at 9;000.  The aircraft turned and was still climbing and the other aircraft was descending. I should have restated the altitude when Tower got in my ear and I didn't hear the read back.
Two reports of an aircraft that was doing what it was told to do.  The error was the departing aircraft was assigned the wrong altitude and came close to traffic that was level on an arrival.