Air Traffic Control Fully Certified
Situational Awareness
ATC Issue All Types; Conflict Ground Conflict; Critical
Air Traffic Control Issued New Clearance; Flight Crew Executed Go Around / Missed Approach
Human Factors
An A319 called up on a Visual Approach to the Runway XXC. I didn't have any aircraft close to Runway XXL for departure; so I switched the A319; and cleared him to land on Runway XXL. Meanwhile; Ground was taxiing about 7 aircraft out for departure; so I was checking the sequence for departure. I requested that Ground Control taxi a Dash-8 to Runway XXL at E to split up two aircraft that were departing westbound one after another. I forgot that the A319 was on final for Runway XXL and cleared a B737 for takeoff. The B737 did not respond. The A319 verified his clearance to land on Runway XXL. Initially; I cleared him to land again thinking that he was lined up for Runway XXC; as forgot I switched him to Runway XXL. I double checked the ASDE-X; looked out the window; realized that I had switched the A319 to Runway XXL and immediately sent the A319 around. The B737 had crossed a few feet over the hold line for Runway XXL; so the ASDE-X Go-Around Alert went off. I coordinated with 'Departure Y' to let him know that the A319 was a go-around; turning right heading 195; and maintaining 2;000 FT. I then shipped the A319 to departure. I would recommend reducing the amount of time I was position late in the evening.
Tower Controller described a directed go around event where he/she failed to realized an arrival aircraft was changed to a parallel runway with traffic cleared for takeoff.