BAe 125 Series 800
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 4
Distraction; Communication Breakdown; Situational Awareness; Training / Qualification
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Human Factors; Procedure
I was the Front Line Manager (FLM) providing a certification skill check on Local Control. Aircraft X; H25B; departed [airport]. Aircraft Y; C152; 6NW VFR southbound transition. Traffic was issued to Aircraft Y and he had the Hawker in sight off the departure end. Traffic was issued to the Hawker and he was looking. Trainee verified the Cessna still had the Hawker in sight about 2 miles apart. Traffic was again issued to the Hawker; advising him that Cessna had him in sight. Hawker was still looking so I motioned with my hand that the trainee needed to do more. Unexpectedly she transferred communication of the Hawker to TRACON. It appeared on the Tower Display Workstation that the Hawker passed under the Cessna before continuing to climb. I ended the skill check and took over. [TRACON] called over a few moments later and advised the Hawker responded to an RA. I contacted the Cessna before he left the airspace and asked if he saw the Hawker pass underneath. The Cessna said the Hawker passed behind him. After I was off position; I pulled the Falcon replay and it showed the Hawker pass behind the Cessna; but only 1/3NM lateral and 100 feet vertical. The Hawker descended 200 feet and returned to his climb shortly thereafter.Based on the previous performance of this trainee; I thought by motioning with my hands she would understand that she needs to do more to ensure separation. The transfer of communication caught me off guard. I've never seen her transfer a conflict before. I always try not to speak during a skill check unless the trainee is missing something or safety is compromised. In hindsight; I should've taken over and ensured the separation myself.
Tower Front Line Manager reported of a loss of separation during a skill check on local position. Developmental did not fix a separation problem and switched both aircraft to Departure Control.