Skylane 182/RG Turbo Skylane/RG
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (mon) 6; Air Traffic Control Time Certified In Pos 1 (yrs) 17
Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic
Procedure; Airport; Human Factors
Sporting event arrival procedures [in effect] (2.5 hours before kickoff; very busy). We had an unusual split of airspace; one Controller working final; and me working satellite airports; feeding the Final Controller; and departures. The C182 was northeast and inbound to GRB at 50. The Cirrus was southeast and heading to SBM (LOA with MKE says we'll give him to them at 50 - which was coincidentally the altitude he came over at from ZMP). I noted a potential conflict when the two aircraft were about 30 miles apart; but wanted to see the situation develop with plenty of time to take steps - unsure if there would be a conflict at that time. Then I went on to other traffic/situations and failed to return to the conflict until it was too late. At that point I put both aircraft on 90 degree headings and descended the Skylane. Too little too late; ZMP - Minneapolis Center; SBM - Sheboygan; WI;= Airport; MKE - Milwaukee Tower/TRACON; GRB Tower/TRACON.I discussed this with my ATM. GRB is unusual in that we are effectively an ATC5 for 350 days of the year; and an ATC10 the other 15. Eight football home games (not counting playoffs) and aviation events are incredibly busy. A three-way split would have alleviated the workload and I believe I would have prevented the incident. We had an agreement (between feeder and final) to set everyone up for a downwind entry for the Back Course 24 approach at 60. But visuals started working and many pilots were requesting the GPS 24 arrival and coordination between the two positions was pretty heavy. I think a stronger controller would have had this ironed out earlier on. I should have descended the Skylane as soon as I could have - rather than putting off the potential situation. I got wrapped up doing other things and didn't get back to it like I should have. The next time I see a potential situation like this; I hope to deal with it at the onset rather than waiting to see if anything comes of it.
GRB TRACON Controller describes a loss of seperation event that occurs during a time of high inbound traffic.