Date: 201704
Local time of day: 1201-1800
Location: GRR.TRACON, MI
Flight conditions: VMC
Light: Daylight
Aircraft: Medium Large Transport
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class C GRR
ATC / advisory: TRACON GRR
Second aircraft: Large Transport
Reporter organization: Government
Reporter function: Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Distraction; Human-Machine Interface; Situational Awareness; Workload
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Executed Go Around / Missed Approach; General Flight Cancelled / Delayed
Contributing factors: Human Factors; Staffing; Aircraft
Primary problem: Human Factors

Narrative: I was working Arrival radar during our extended radar outage. I had a sequence of 4 aircraft and a VFR practice approach on final. Two aircraft were joining the downwind for Runway 26L. Aircraft X was from the south; and I was attempting to 'chase' Aircraft Y to follow him to the airport. I had originally descended Aircraft X to 3000 feet and Aircraft Y to 5000 feet. I changed the altitudes and descended Aircraft X to 4000 feet and Aircraft Y to 3000 feet. Because of this Aircraft Y ended up at the same altitude as Aircraft X. I was late to notice this because there was no Conflict Alert and no RA from the pilots. I called the traffic to both pilots but was delayed doing so as the radar was updating so slow; and the data tags became overlapped. Both aircraft had the other in sight; however; I had already lost separation between the two. I cleared Aircraft Y for the Visual Approach rather than bring him through the localizer like I should have done. A VFR Aircraft Z was on a 2 mile final. I called upstairs to ask Tower to break out the Aircraft Z. I should have asked them to turn the aircraft southbound; but I was desperate to just have the aircraft out of the way. Once I cleared Aircraft Y I turned Aircraft X to a 090 heading and eventually brought them in once everything was resolved. GRR is on a long term radar outage; and plans to be on CENRAP (TRACON using long range Center radar feed) for an extended period of time. We are fighting staffing issues and trying to train new controllers. Today we were below our staffing numbers for the day but a Supervisor was filling in for a controller that was on sick leave. The Supervisor was busy doing other tasks and the TRACON was being run on a single person rotation. This should not happen when we have the added complexity of CENRAP added to our workload. I am a trainer for a Tower trainee; and the other member of the team is a trainer for someone in the TRACON. Because of this; we both only get minimal time on the position we aren't training on. I felt very rusty in the radar room; and it showed when a complex problem developed. Due to being on CENRAP there was no Conflict Advisory warning. This is something I completely forgot about. Especially since the Supervisor came into the TRACON earlier in the day and tested the alarms to make sure they worked. We are regularly without a Supervisor monitoring the operation. Lately they have been on leave; or attending training elsewhere; leaving us short on supervision. This increases the workload on the Controllers who are already busy working traffic; and training.


Second narrative: [Report narrative contains no additional information.]


Synopsis: A TRACON Controller utilizing Center Radar procedures reported vectoring two aircraft heading to the final approach course onto conflicting courses.