Date: 201911
Local time of day: 1201-1800
Location: SLC.Tower, US
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B SLC
ATC / advisory: Tower SLC
Second aircraft: Small Aircraft
Reporter organization: Government
Reporter function: Local
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Distraction; Workload; Situational Awareness; Confusion
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Incursion Runway
Detector: Person Air Traffic Control
When detected: Taxi; In-flight
Result: Air Traffic Control Provided Assistance
Contributing factors: Procedure; Aircraft; Company Policy; Human Factors
Primary problem: Human Factors

Narrative: I was working the Local Control East Position (LCE) combined with The City Control Position (CTY); [for 2 hours] during what we refer to as the Arrival Bank. We were on a South Flow using Runways 17 & 14 for Arrivals on the East Side. This morning was a particularly foggy part of the day with haze and ground fog obscuring visibility on the east ramp area so much that you could hardly see any of the vehicles or small civilian aircraft taxing on Taxiway Kilo (K). Also please note that we have a lot of primary targets generated from many vehicles that use taxiway Kilo on a continuous basis throughout the day (24 Hrs/Day) without any communications with either Local Control East or Ground Control East. Also the Airport Operations [vehicles] will drive in and out of east taxiway; right up to the hold short lines; continuously; to inspect the pavement throughout the day.I was working a busy arrival bank of aircraft on the LCE position; combined with the CTY position. Everything was fairly routine throughout most of the bank.Aircraft Z who had taxied out for takeoff to Runway 17 via Kilo apparently decided to return to the ramp. While this aircraft was taxing back into the ramp they stopped in the middle of Taxiway Kilo between K8 & K7. Ground then stated that Aircraft Z had stalled his aircraft and needed to be towed into the ramp. I told Ground Control that he was welcome to taxi the small aircraft to Runway 14 if he needed to accommodate the small departure aircraft.I had a departure strip on Aircraft A at Taxiway K5 for crossing to Runway 14 for Departure. I instructed Aircraft A to cross Runway 17 and taxi to Runway 14 without delay and issued traffic; Aircraft X on a 3 mile final to Runway 17.I observed Aircraft B complete the runway crossing and was taxing to Runway 14 on Taxiway Quebec. Aircraft X was on a 2 Mile Final.Approach Control called me to coordinate Aircraft B; who had just departed; climbing to 9;500 feet and that there would be further coordination concerning any restrictions needed for departures. Then they asked me if Aircraft C had seen the traffic at 4;200 feet that they were issued just north of 'The Barn' (VFR Navigation Point). I glanced at the Radar Scope to locate Aircraft C and since I couldn't quite hear everything he said about Aircraft C so I asked them to repeat. Once again they asked about the traffic north of 'The Barn' and I replied that they hadn't said anything to me about it.Because I looked at the Radar scope to locate Aircraft C and the traffic he was issued; I never saw the primary only target (Aircraft Y) that had just crossed Runway 17 at Taxiway K5.Coordination was complete and I scanned Aircraft X; who was on a 1/2 mile final; to check for landing gear.As I was scanning; I keyed up and told Aircraft A to let me know when they were ready to depart. They replied. (According to the ASDE Play back; Aircraft Y had just exited Runway 17 (Primary Only Target).At this time as I was scanning down the Runway Aircraft Y called me at stating 'Aircraft Y is with you on Quebec.' Also at that exact moment the Departure Tag had just acquired. (This was the first time I even saw Aircraft Y on Quebec clear of Runway 17 taxiing towards Runway 14. I only had one Departure Strip in front of me on Aircraft A so I wasn't even aware that another aircraft was taxing to hold short of Runway 17 at K5.)I was a bit startled so I asked the Skyhawk calling to repeat. Aircraft Y again states that he is with me on Taxiway Quebec; to which I replied 'Roger.' I looked back at Aircraft X and he was just crossing the threshold of Runway 17; in the flare (Critical stage of flight). I couldn't believe that I had missed that. Of course since the Skyhawk was already off Runway 17; I didn't even attempt to send Aircraft X around.I let Aircraft X roll out and then I keyed up and asked Aircraft Y how he got onto Taxiway Quebec.Aircraft Y replied that he was cleared to cross Runway35 on K5. I replied that the crossing instructions were for Aircraft A.I exited Aircraft X onto Taxiway Papa and told them to cross Runway 14. I then issued follow up instructions for Aircraft X; a couple of times and ensured a good read back of the hold short instructions. I continued to work my traffic as I coordinated with the Tower Supervisor on duty to request permission to issue Aircraft Y the Brasher.I issued the Brasher to Aircraft Y; to contact the Tower for possible pilot deviation and told I had the phone number when he was ready to copy. I then issued the Salt Lake Control Tower phone number.In addition to the above; the tapes reveal that I crossed Aircraft D; Heavy; whom I saw during my scan holding short at Taxiway K7; and the ASDE X never showed a target on this aircraft. Also the ASDE X never alerted on Aircraft Y crossing the runway at K5 with Aircraft X on a ? mile final.I feel this event happened because I was taking a coordination call during the time that the event occurred; on an additional position (CTY Position) that I might not have received if the positions had been split off for the Arrival Bank. It was however pretty hazy outside on the east side making it difficult to even see any vehicles or small aircraft taxiing on Taxiway Kilo.I am also hearing from others that the current Temporary ATM; was calling in during the bank; asking the Supervisor if The Local East Controller was actually doing his job scanning the runways or not paying attention to the traffic; and why I had not seen the primary target cross the runway in front of Aircraft X.Even though this is a pilot deviation; I feel like I am being targeted as the reason this happened and that it is somehow my fault. I did the best I could with the situation at hand. I wish I could have seen the runway incursion take place as I would have sent Aircraft X around to ensure his safety.I asked a couple of Supervisors on duty if they felt it was possible keep track of every primary only target on Taxiway Kilo during a busy bank like that. They told me they didn't think that was possible.Currently the positions in the tower have been mandated by the Temporary ATM to be split off most of the day even when traffic is extremely slow. [I] am aware of the fact that the majority of events; or loss of separation happens when positions are split when it is slow.In this case the position was combined up during a busy IFR arrival bank with hazy visibility due to facility staffing. I recommend that the LCE position be split off from the CTY position during any major arrival or departure banks to alleviate congestion on the frequency and to better serve those who need to coordinate without compromising safety.




Synopsis: SLC Tower Controller reported working two combined positions and that the resulting high workload caused a runway incursion.