A Tower Local Controller and the Controller in Charge reported the Local Controller anticipated the landing aircraft would exit the runway but it stopped to ask for taxi instructions as a departing aircraft was taking off behind it.
Synopsis
A Tower Local Controller and the Controller in Charge reported the Local Controller anticipated the landing aircraft would exit the runway but it stopped to ask for taxi instructions as a departing aircraft was taking off behind it.
Narrative
Aircraft X landed Runway X and began slowing down to taxi speeds during their landing roll approaching the taxiway. Controller cleared Aircraft Y for takeoff Runway X full length using anticipated separation. When Controller turned back to Aircraft X they realized the aircraft had come to a full stop on the runway and was now occupying the frequency asking where Controller like them would turn. Controller then told Aircraft X to exit the runway on taxiway to the right. By then Aircraft Y had begun their takeoff roll before Aircraft X could exit fully. I had missed Aircraft X stopping on Runway X as Controller in Charge (CIC) due to myself scanning elsewhere on the field working Ground Control. Personally; my scan could have been prioritized differently to catch an aircraft coming to a complete stop on the active runway. Pilots often exit the runway if not given instruction when it is safe to do so. Anticipated separation is used often as safely in order to efficiently keep traffic flowing.
Second reporter narrative
Aircraft X was on landing roll out on Runway X and had slowed down to taxi speed. I cleared Aircraft Y for takeoff thinking Aircraft X would continue taxing off the runway. As I scan back down the runway I observed Aircraft X has come to complete stop on Runway X abeam the taxiway. Before I can key up to tell him to continue off the runway; the pilot keys up and asks me where they should turn off; should they make a right or left off the runway. By this time Aircraft Y is already on takeoff roll and airborne. I proceed to tell Aircraft X to make a right on taxiway and contact Ground Control. Once on ground Aircraft X is issued a BRASHER by the Ground Controller. Ascertain that the aircraft was making the turn off the runway before issuing a departure clearance to the other aircraft. Also; discuss with local safety council as this has not been the first time that aircraft have stopped on the runway and asked Controllers for instructions on where to exit the runway.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.