Small Aircraft
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 1.25
Distraction; Situational Awareness
ATC Issue All Types; Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Air Traffic Control Separated Traffic
Procedure; Human Factors
I was On the Job Training Instructor (OJTI) on ground and FD/CD combined. Aircraft X landed runway 19R and local instructed them to turn left on taxiway C and hold short runway 19L; which they did. Aircraft Y landed runway 19L and was instructed to continue down to taxiway L and turn left and to contact ground. Aircraft Z was in left closed traffic for runway 19L and was on final for runway 19L. Without looking up tower told Aircraft X to cross runway 19L and contact ground on the other side while Aircraft Z was on short final (about 300 feet from runway threshold). I called out 'on final.' The Local Controller then instructed Aircraft X to hold short runway 19L and apologized to them. Aircraft X stopped on the hold short bars but did not cross them; nor did he cross the runway edge line. Local was preoccupied with personal distractions at his position and I believe that he forgot about Aircraft Z. I believe that if he had been looking out the window he would have easily seen Aircraft Z on short final. I believe that all personal materials and electronics should be banned from the tower cab. Not just in the off position or at a charging station; but in lockers in the break room. It's too easy for someone to have distractions put away while management is in the cab; but once they leave items on the back counter can become a distraction.  By banning all personal items and electronics and doing random checks I believe more focus would be paid to traffic outside. Some controllers have already adopted this practice voluntarily.
Ground Control instructor hears Local Control cross an aircraft with an aircraft on short final. Local stops the crossing; but the aircraft is on the hold short bars. Local Control was distracted with personal issues and did not look up when giving the crossing instruction.