Helicopter
Air Traffic Control Developmental
Air Traffic Control Time Certified In Pos 1 (yrs) 1
Situational Awareness; Training / Qualification; Communication Breakdown; Confusion
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Executed Go Around / Missed Approach
Procedure; Human Factors
I was training on local with my trainer closely monitoring me when Aircraft X calls. 'Aircraft X just over the Marina to the south requesting north shoreline transition to the 10 FWY East/Getty.' This is where the miscommunication occurred I heard 'To the Getty; east.' I responded 'Aircraft X transition approved; cross midfield at or above 900ft.' Aircraft Y calls in on the VOR/GPS-A approach; was cleared for the visual and cleared to land on RWY 21.At this time Aircraft X crosses mid field and proceeds to cross my final along the 10 FWY east; with Aircraft Y on a 2.5 mile final. This was observed and action was immediately taken to de-conflict the traffic. 'Aircraft X you are crossing my final; remain north of my final.' At this point my trainer chimes in to ensure the situation would remain safe. Aircraft X turn left immediately; you're flying up my final.' I key up and say 'Aircraft Y traffic ahead and to your right; a helicopter turning northbound for you.' Aircraft Y replies; 'We got an RA on that guy we have him in sight; we're going to have to go around.'Possibly establish VFR helicopter routes that prohibit helicopters from transitioning in an unsafe manner through the Class Delta. For example: Aircraft transitioning out of the LAX shoreline route must continue low level along the shore until reaching the Pier.
SMO Developmental Tower Controller reported of issuing instructions to a helicopter. The aircraft did not fly as instructed and became a conflict for arrival traffic. Instructing Controller turned the helicopter to avoid the arrival. Arrival aircraft reported an RA and advised Tower they had the aircraft in sight.