EMB ERJ 145 ER/LR
Air Traffic Control Fully Certified
Human-Machine Interface
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
ATC Equipment / Nav Facility / Buildings; Human Factors
I was working East Arrival vectoring to Runway 22R ILS. Air Carrier X was established on the 22R ILS; 20 [NM] northeast of ORD at 7;000 FT. Air Carrier Y was on vectors from SBN 20 [NM] ENE at 7;000 FT. Initially [they were] on a 290 heading to go behind Air Carrier X. Both aircraft were operating at 250 KTS. I had to adjust heading to 310 and then 330 to stay behind Air Carrier X. I did get Visual Separation just prior to proximity being less than three miles laterally. Divergence was also in effect as the 310/330 headings were essentially a base leg and Air Carrier Y was on course to pass behind Air Carrier X. No Conflict Alert was activated. I feel the Fusion Radar presentation threw off my estimation of the closure rate and the converging courses; and it ended up being closer than I would have liked. My perception is that the Fusion display appears to jump with regard to the target position; refer to as 'stitching'. I am still getting adjusted to correlating target movement relative to the ground speed read out; especially when vectoring to the final approach course at the speeds we are accustomed to working. I intend to build in a little more 'margin' on headings; spacing and speeds; particularly when vectoring to the final approach course.
C90 Controller described a loss of separation event while working aircraft to the final; the reporter claiming the Fusion Radar contributed to misapplication of separation required.