Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 1
Troubleshooting; Workload; Communication Breakdown; Confusion; Distraction; Situational Awareness
Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Air Traffic Control Issued Advisory / Alert
Procedure; Human Factors
I was working LC1; I cleared Aircraft X for takeoff; after Aircraft Y had completed his landing roll I instructed Aircraft Y to hold short of Runway 25R at A7; and I received a proper read back of the required hold short instructions. I then went to work trying to sort out the horrible sequence my ground controller had given me. I was looking at my upcoming departure strips when the ASDE-X alarmed stating 'Runway 25R occupied!' I immediately looked up to see Aircraft Y crossing Runway 25R at A7 while Aircraft X was rolling down Runway 25R at a very high rate of speed; too late to cancel their takeoff clearance. I attempted to key up to resolve the situation; but it was too late to do anything about it. Aircraft X rotated a couple seconds later somewhere between A5 [and] A6 and departed overtop of Aircraft Y still on the runway. I advised Aircraft Y their instructions were to hold short of runway 25R; to which he replied 'yeah we screwed up.'Even if I hadn't had a bad departure sequence; the events happened so fast I'm not sure it would have been caught in a normal scan with the traffic volume at the time.
LAS Tower Controller reports of a runway incursion caused by a pilot who did not hold short as instructed. Departure aircraft had been cleared for takeoff and was rolling when ASDE-X alerted controller of the incident. Controller did not have enough time to react and departing aircraft flew over crossing traffic.