Date: 201204
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Weather elements / visibility: Rain; 8
Light: Daylight
Aircraft: Cessna Single Piston Undifferentiated or Other Model
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Flight phase: Taxi
ATC / advisory: Tower ZZZ
Second aircraft: B737 Undifferentiated or Other Model
Reporter organization: Government
Reporter function: Local
Reporter qualification: Air Traffic Control Developmental
Human factors: Communication Breakdown; Confusion
Second reporter function: Single Pilot; Pilot Flying
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway; Ground Incursion Taxiway
Detector: Automation Air Traffic Control; Person Air Traffic Control
When detected: Taxi
Result: Air Traffic Control Issued New Clearance; Flight Crew Executed Go Around / Missed Approach
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: A Cessna (call sign XXX) was in position on Runway XXL; waiting for traffic to depart Runway YYL. Air Carrier Y; [B737]; was on short final to Runway XXR. The Cessna was holding short of Runway XXR waiting for their turn to depart. When a similar call sign (XXY) was cleared for takeoff on Runway XXL; the Cessna (who was holding short of Runway XXR) incorrectly thought that the instruction was for him. The Cessna proceeded to cross Runway XXR on his way to Runway XXL; with a B737 now on very short final for Runway XXR. The B737 was issued a go-around due to traffic on the runway. I worked to separate the B737 from traffic departing Runway XXL as well as the traffic that had just departed Runway YYL. The Cessna had now crossed Runway XXR and asked if they were cleared for take off on Runway XXL; and I told them 'negative; hold in position'. I wanted to hold the Cessna on the ground until we had a chance to sort things out. I then noticed an aircraft in downwind for Runway XXL; so I cleared him to land. The landing aircraft turned final for Runway XXL while the Cessna was still holding in position; so the ASDE-X alarm sounded. I changed the landing aircraft to Runway XXR; issued landing clearance; and he landed on Runway XXR. The relieving Controller took over; and they taxied the Cessna off of the runway and held him short of Runway XXL. Recommend continued scanning of all areas to ensure that the correct planes are doing what they were instructed to do. When there are similar sounding call signs; make sure that only the correct plane answers the instruction. Although we clearly heard call sign XXY acknowledge take off clearance; there was also a ringing sound in the background of the frequency which may have been the Cessna (call sign XXX) trying to read back the clearance but getting blocked by the other's transmission. When holding a plane on the ground to decide what action is to be taken; do not hold them on the runway. Make sure that they clear the runway and instruct them to hold short instead.


Second narrative: There was another plane lining up for takeoff with the call sign XXY. My call sign is XXX. I repeated the instructions to cross Runway XXR and line up and wait on Runway XXL. According to the Tower; call sign XXY and I both squelched at the same time; but they only heard call sign XXY affirm the direction. I didn't hear call sign XXY because we both responded at the same time; so I proceeded. I had information Quebec when I prepared for the flight; and I thought Tower said that it had switched to Romeo. There was a Boeing on a short final on XXR as I crossed that I didn't see. I thought it was clear when I started to cross XXR; and thought I had clearance to do so. While I was waiting on XXL; Tower instructed call sign XXY to set their transponder and I thought they were addressing me; so I asked for clarification. It was at this time that I realized that there was another aircraft with a similar call sign. I was on the runway for about 5 minutes waiting for direction and I inquired about my clearance. Tower instructed me to exit the runway and call them. It was also a rainy/cloudy day. I'm a new private pilot and I have a lot to learn. I am extremely humbled by this experience and thankful that my misunderstanding didn't cause harm to anyone.


Synopsis: Tower Controller described an unauthorized runway crossing event that resulted in a go around; the reports indicating similar call signs; missed read backs and minimal experience levels as contributing factors.