Ground Controller described a developing conflict involving a Flight Check operation and another inbound air carrier aircraft.

Narrative

A King Air 200 was performing a Flight Check of the Runway 28 ILS. An Embraer E-145 was on the visual approach for Runway 24R; the arrival runway. The Local Controller (LC) advised the Flight Check of the traffic and they reported the traffic in sight. Local Control advised the Flight Check to maintain visual separation with the E-145. Local Control advised the Embraer of the traffic and that the Flight Check was maintaining visual separation. On about a 4 to 5 mile final; both aircraft were in a tie situation; where the Embraer would have not crossed the projected flight path of the Flight Check before they crossed the landing threshold of Runway 28 to complete a low approach. I was working Ground Control (GC) during the event and advised the Local Controller verbally that the aircraft were tied. The Tower Supervisor then suggested to the Local Controller to give the Embraer an S-turn and to advise the aircraft to reduce to final approach speed; the Local Controller complied. He also called the traffic to Embraer an additional time. As the S-turn and speed reduction did not result in any change; the Tower Supervisor then suggested to side step the Embraer to Runway 24L. The Local Controller complied as the Embraer was about 2/3rds of the way through the S-turn; now headed right at the Flight Check aircraft. Within one mile of the Runway 24L threshold; both aircraft were on a path that prompted the STARS to display a collision alert. The AMASS also alerted that Runway 28 was closed as Flight Check approached the Runway 28 threshold. Realizing that the situation was not going to work; the Local Controller instructed the Embraer to 'go-around.' When both aircraft were at the 5 mile range ring on the Tower TDW display; I realized that even though the Embraer was faster than the Flight Check; by time the Embraer slowed for a landing; both aircraft would be a tie over Runway 28 near the Runway 24R approach end. These runways do not intersect; but flight paths do cross as runways are in close proximity. Seeing this; I advised the Local Controller that the situation was not going to work. However; the Tower Supervisor also realized the situation required additional attention and began assisting the Local Controller. Coordination between the Tower and Arrival RADAR was conducted. However; I do not know what the coordination entailed outside of the Tower. It would have been more beneficial and more efficient to have the Flight Check talking to the Arrival Controller as there were several arrivals inbound just after the event. Arrival RADAR controllers should be talking with the aircraft conducting any sort of converging runway operation. Better; more effective and complete; coordination should be accomplished prior to conducting this operation so that all personnel involved are aware. Since there was time to avoid the situation; better judgment should have been applied and additional training should be conducted on converging runway operations as it is an uncommon operation here. Current converging runway operations should be reviewed to completeness and accuracy and reviewed with controllers on a regular basis. Training for converging runway operations should also be reviewed for completeness and accuracy.