Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 10
ATC Issue All Types; Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic; Flight Crew Took Evasive Action
Human Factors; Procedure
We had just received our position briefing; at this time I plugged in being the trainer. I looked up and saw an aircraft exit Runway XX at Charlie. At that time I rerouted my headset cord around some hidden hooks so the cord doesn't get in the way of the trainee. As this happen the trainee made a transmission to Aircraft X to taxi via Charlie; cross [RWY] YY; then Mike 3 Mike to the ramp. The pilot read back everything correctly. At this point I had just finished routing my cord (5 seconds or less) I then look up and see an aircraft exiting [RWY] XX on Charlie had stopped. Aircraft Y was cleared for takeoff Runway XX and was rolling down the runway. Another aircraft had just exited XY at Charlie and was taxiing fast towards Runway XX. At this point everyone was yelling stop. The Ground Trainee yelled stop. At this point Aircraft X stopped in the middle of Runway XX. Local had told Aircraft Y to stop. Aircraft Y stopped a few thousand feet before Aircraft X. What happened is the trainee got the aircraft mixed up and used the wrong call sign. Aircraft Z exited Runway XX at Charlie; and Aircraft X exited Runway XY at charlie. The pilot of Aircraft X read back cross Runway YY at Charlie but instead crossed Runway XX at Charlie without clearance. The controller mixed up two aircraft both taxiing on Charlie. Aircraft X crossed Runway XX at Charlie had not been given clearance to cross that active runway but instead was suppose to cross Runway YY.
Instructing Controller reported experiencing a ground conflict due to Developmental using the wrong call sign between aircrafts.