Date: 201907
Local time of day: 1201-1800
Location: DFW.Airport, TX
Light: Daylight
Aircraft: Medium Large Transport
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
Airspace: Class B DFW
ATC / advisory: Tower DFW
Second aircraft: Large Transport
Reporter organization: Government
Reporter function: Local
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Distraction; Situational Awareness
Second reporter function: First Officer; Pilot Flying
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Critical
Detector: Person Flight Crew
When detected: Other Takeoff
Result: Air Traffic Control Issued New Clearance; Flight Crew Rejected Takeoff; Flight Crew Requested ATC Assistance / Clarification; General Flight Cancelled / Delayed
Contributing factors: Human Factors; Airport; Procedure
Primary problem: Human Factors

Narrative: I was working Local Control position with the other Local Control split off from my position. I had crossed Aircraft X over both Runways 18R and 18L. I had crossed him over both because I had some space due to a CRO (Converging Runway Operation) aircraft arriving Runway 13R. Aircraft X took longer to cross than I had anticipated and he hadn't finished crossing Runway 18L when I scanned my runway. I was out of my normal flow due to the CRO and I was trying to get my next departure out before the next aircraft entered the CRO box for Runway 13R. I completely forgot about Aircraft X crossing and cleared Aircraft Y for departure. Aircraft Y started takeoff roll and Aircraft X was crossing. Aircraft Y saw Aircraft X and aborted his takeoff roll. I then issued the existing instructions to Aircraft Y. I got too focused getting my departures out and watching Final for Runway 18R and got out of my normal rhythm.When aircraft are arriving Runway 13R I prefer to have an assist position instead of splitting of the Local Control position. I feel like the extra set of eyes in this situation may have helped me and slowed me down some. I also think that having someone work the push towards the end of their time on position is not ideal; I prefer to work at the beginning of the push through the whole push so that I am at my most aware and ready.


Second narrative: We were cleared for takeoff after lineup and wait on Runway 18L for converging runway traffic. Normal flex takeoff set and transfer of thrust levers. While accelerating we observed Aircraft X crossing the runway right-to-left; downfield. Runway status lights illuminated just as I was inhaling to alert the CA (Captain) of Aircraft X. Captain called abort; I replied 'your aircraft'. I believe the speed was about 50 to 60 knots. Auto brakes did not activate. I told Tower 'Aircraft Y is aborting'. We turned off Runway 18L. The Captain made a PA. We were cleared to taxi back to Runway 18L. We re-did the Before Takeoff Checklist and took off uneventfully. The Captain and I found it interesting that Aircraft X never made a radio call and the Tower never spoke to it. We were also surprised the aircraft crossed the runway while we were clearly rolling and had all our lights on. Surmise other aircraft must have been on wrong frequency. Luckily there was adequate space for us to reject the takeoff but we both saw Aircraft X rolling toward the runway. Runway Status Lights also were very helpful.


Synopsis: DFW Tower Controller reported clearing an aircraft for takeoff while another aircraft was taxiing across the runway. First Officer of aircraft taking off also reported seeing aircraft crossing runway.