Flight Crew Air Transport Pilot (ATP)
ATC Issue All Types; Conflict Airborne Conflict
Air Traffic Control Issued New Clearance; Flight Crew Executed Go Around / Missed Approach
Human Factors; Procedure
ATC directed go-around on short final. Inside the final approach fix; the Tower Controller instructed an aircraft to 'line up and wait;' adding that an aircraft will cross down field. After the aircraft accepted the clearance to line up and wait; Tower issued instructions for another aircraft to cross the runway at Taxiway N. The aircraft that was crossing the runway took his time; delaying the takeoff clearance to the point that spacing became an issue. It was my observation that the aircraft on the takeoff roll might lift off; allowing us to continue the approach to a landing. The go-around was initiated prior to 120 FT; however; that was the lowest RA observed after the application of TOGA thrust. Tower issued a climbing left turn to 4;000 FT; heading 270 degrees. My concern during the latter portion of the approach was that a go-around initiated on our part would create a conflict with the aircraft on takeoff roll; (overtaking) and/or a possible conflict with a go-around or takeoff on the parallel runways. In my opinion it was safer to continue the approach than to initiate a go-around on our own. As a result; the go-around was initiated after Tower issued the go-around instructions. As our aircraft passed over the numbers on the go-around; the aircraft on the runway rotated. Inexperienced Tower Controller who attempted to 'keep the operation moving' complicated by slower than normal taxi speed of aircraft crossing the runway.
A321 Captain reports being issued a go around on very short final due to the departing aircraft not being airborne. The reporter had determined that a go around would be necessary but elected to wait for the ATC instructions due to possible conflict with the departing traffic ahead and off parallel runways.