Large Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 1.9
Confusion; Distraction; Workload; Time Pressure; Situational Awareness
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Airspace Structure; Human Factors; Procedure
Was working LA2 (Local Assist) during a very busy time. FIXIT departures were on; requiring additional in trail spacing; which was adding complexity to the already busy traffic. I had a sequence set for Aircraft Y off of SMO but when I requested release from Malibu sector they were overwhelmed and needed to call me back. Meanwhile the FIXIT departures were canceled and we went back to regular spacing; which changed the sequence again. Instead of giving SMO a '1 min heads up' for departure I told them it would be a while because I was waiting for Malibu to call me back. SMO holds all departures back from the runway due to noise and pollution restrictions at their airport; we give them the 1 min warning so they can taxi the aircraft out to be ready to go. We had one last departure rolling when Malibu called and released Aircraft Y. I released Aircraft Y off of SMO thinking the aircraft would still need to taxi out for departure. But both aircraft ended up airborne at the same time. Just under 4 miles apart. In the future I will verify with SMO where there aircraft is to ensure separation.
LAX Tower Local Assist reported releasing an aircraft off SMO. There was a loss of separation between it and a LAX departure.