Large Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 2.5
Distraction; Situational Awareness
ATC Issue All Types; Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Human Factors; Procedure
Aircraft X was cleared to land runway 17R at which time I placed the appropriate memory aid device on my runway 17R board. I turned my back on the position to converse in a discussion that was going on behind me. When I turned back to the window I switched another aircraft that was departing runway 8 to Denver departure and inadvertently removed the wrong strip holder which was the memory aid for runway 17R. I turned back to my conversation then noticed I had a departure waiting for runway 17R.I scanned my runway and did not notice any aircraft on the runway and with no memory aid on my board I cleared Aircraft Y for takeoff. Aircraft Y acknowledged the clearance and started to taxi on the runway. Aircraft X was just landing and rolling down the runway. Again I turned back to finish the conversation when Aircraft X replied to the tower that he was still on the runway. Aircraft Y was told to 'Line up and wait'. The pilot of Aircraft Y acknowledged the transmission and said that sounded better. Once Aircraft X exited the runway Aircraft Y was given takeoff clearance and departed.Distractions in the tower are normal everywhere. The Local controller should have been more attentive to the position and if a discussion was needed it should have been conducted once relieved from work duties.
DEN Tower Controller reported clearing an aircraft to land then joining a discussion. Controller used a memory aid to remind him of the landing traffic. Controller then did a few other things and removed the memory aid and joined the conversation again. Controller then scanned the runway seeing no traffic on it and cleared the next aircraft for takeoff. Traffic was on landing roll and the pilot advised Tower they were still on the runway. Controller told departing aircraft to line up and wait. Controller is aware of distractions and stated that he should have been more attentive to the position.