Tower controllers reported a miscommunication between ground and local control resulted in a runway incursion and a critical ground conflict.
Synopsis
Tower controllers reported a miscommunication between ground and local control resulted in a runway incursion and a critical ground conflict.
Narrative
At approximately XA:30z LC (Local Control) informed me I could cross runway XX at [Taxiway] 1. I responded 'cross runway XX at...with who?'. LC responded 'Aircraft X they're going to [The] Ramp'. I responded 'ah; ok; cross runway XX at 1.'. other aircraft had called for their push/taxi from the terminal. After issuing their taxi instructions clearance delivery (combined with tower CIC (Controller in Charge)) informed me they could swap the times for the aircraft since the lead aircraft coming out of the terminal had a later time than the trailing. I informed clearance delivery I had already worked it out with differing taxi instructions for the aircraft to change the order and not to change the times. I believe around this time Aircraft Y had called for their taxi from runway XY at 1. I looked at the local control position; saw the runway XX/XZ crossing memory aid; and issued taxi instructions to Aircraft Y with clearance to cross runway XX at 1 they read them back correctly. Realizing I had no confirmation from Clearance delivery that the previous mentioned aircrafts times were not going be switched I turned back to CD (Clearance Delivery) and verified that he heard me and the times didn't need to be switched. CD told me he didn't switch them and then Aircraft Y called; sounding fairly shaken; and as I turned back I saw an aircraft midfield departure on runway XY crossing the intersection of runway XY and XX. I looked to LC control and started to ask what was going on and he cut me off informing me that he was aware of his mistake. Aircraft Y said something that I couldn't quite understand. thinking they were angry and asking for the tower number I offered them the number then they said they were waiting for taxi confirmation. So; I continued their taxi via 1;2;3;4 without further incident.Recommendation: No idea. I was told to cross the runway so I crossed the runway. Heavy workload and complexity issues with flow times/departures took all of my attention and I didn't hear LC clear someone for take off on the runway they approved me to cross.
Second reporter narrative
I was working Controller in Charge and CD (Clearance Delivery) combined. Had been directly monitoring the operation for most of my time; but after some workload for CD had come up; I did not restart directly monitoring LC (Local Control) /GC (Ground Control). I was reviewing flow times and monitoring the outbound flow; when I heard GC talking to Aircraft X when the pilot confirmed that they were cleared to cross RWY XX; as they must have seen an aircraft taking off as they finished crossing. After reviewing what had happened; it appeared that LC gave GC a crossing clearance and got distracted or forgot; and issued a takeoff clearance to Aircraft Y; who departed the runway as the crossing was happening. Recommendation: It would have helped if there was a standalone CIC. Also; Controller in Charge should usually be combined to GC; but at the time it did not seem effective to move the CIC; adding another brief during a busy time.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.