Narrative:

I was conducting OJT on the final vector position. My cpc/it was doing a good job separating aircraft and I was standing behind monitoring the position. I was having difficulty seeing the *T function alphanumerics (which give the distance between two targets); and I moved over to the empty radar position to the left to set it up for better viewing. While I was setting this up; I noticed a possible shrinking of the distance between a C402 following a PC12. I could not be sure of the situation because the data tags on the scope I was sitting in front of were obscuring the *T alphanumerics. By the time I made all the entries necessary for me to see the data; the situation had deteriorated and I prompted my developmental to call the tower and initiate a go around; which they did. Recommendation; it would be helpful if the *T function could be made more useful to controllers. It is by far the most used tool at A90 TRACON used for separation insurance. It is far superior to J rings and/or the cones that have been designed for this purpose because it gives you actual distance and trend information if you are paying attention. However; it has some serious limitations. Right now; a controller can only assign three *T functions at any one time. This should be increased so that any and all aircraft on a final approach course can be connected by *T lines. At boston; that would mean that we would need up to 7 or 8 *T functions available. Also; if the *T data would somehow automatically offset from the data tags (as a default and unless deselected by the controller) this would also be helpful - especially in the situation that prompted this report. When we are on runway 27 at boston; the *T alphanumerics are difficult to read because of their fixed relation to the target (the line goes through the data and the target trails also obscure the numbers). If they had the ability to offset; both of these problems would be eliminated and the data would be much more useful.

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Original NASA ASRS Text

Title: A90 Controller; conducting OJT; described a go-around event when an over take scenario developed on final; the reporter alleging additional 'T' functionalities would help prevent separation losses.

Narrative: I was conducting OJT on the Final Vector position. My CPC/IT was doing a good job separating aircraft and I was standing behind monitoring the position. I was having difficulty seeing the *T function alphanumerics (which give the distance between two targets); and I moved over to the empty radar position to the left to set it up for better viewing. While I was setting this up; I noticed a possible shrinking of the distance between a C402 following a PC12. I could not be sure of the situation because the data tags on the scope I was sitting in front of were obscuring the *T alphanumerics. By the time I made all the entries necessary for me to see the data; the situation had deteriorated and I prompted my developmental to call the tower and initiate a go around; which they did. Recommendation; it would be helpful if the *T function could be made more useful to controllers. It is by far the most used tool at A90 TRACON used for separation insurance. It is far superior to J Rings and/or the cones that have been designed for this purpose because it gives you actual distance and trend information if you are paying attention. However; it has some serious limitations. Right now; a controller can only assign three *T functions at any one time. This should be increased so that any and all aircraft on a final approach course can be connected by *T lines. At Boston; that would mean that we would need up to 7 or 8 *T functions available. Also; if the *T data would somehow automatically offset from the data tags (as a default and unless deselected by the controller) this would also be helpful - especially in the situation that prompted this report. When we are on Runway 27 at Boston; the *T alphanumerics are difficult to read because of their fixed relation to the target (the line goes through the data and the target trails also obscure the numbers). If they had the ability to offset; both of these problems would be eliminated and the data would be much more useful.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.