Narrative:

I was working flight data during a busy and complex session where we were using 'multimode' radar rather than our usual fusion mode. I heard a pilot on frequency that he was maneuvering to avoid a VFR aircraft. He then asked the radar controller if a VFR target had been seen. The answer was no. I feel that due to the complexity and workload at the time it would have been difficult to see the traffic. After the incident happened I observed the VFR tag behind the regional jet. While observing over the next few minutes I saw an intermittent altitude readout of 8500 feet. I tagged up the target manually and asked if the adjacent approach control would continue to track the aircraft to see if we could get their perspective on the event.I think the complexity and added workload contributed to the controllers failure to give a traffic advisory. When the main radar site is out of service we go into multimode which requires us to coordinate departures and arrivals into and slows our automation as well as changes our radar quality and video display. We also had outages that involved frequently used radio frequencies creating a situation that required telephone calls to center for coordination. All of this more labor intensive work takes away from our ability to watch the traffic on the screen and provide as good a service.several hours later I was informed by our supervisor that the problem with the radar was not serious enough for our tech ops to work on it and that we should not have been in multimode for most of the day. I think there is a problem here because no one informed us about what the malfunction was; nor when it was fixed/determined to be not worthy of fixing. The status of the equipment was definitely not relayed as it should have been; causing higher workload and a higher potential for reduced attention and service; possibly reduced safety overall.I would recommend a review of the communication lines from the TRACON and tech ops and how information is relayed about equipment outages; especially when no one from tech ops is actually working. I wonder if sometimes TRACON calls techops; leave a message; and never follow up so nothing gets taken care of. I don't think the radar outage caused the near midair collision; but it may have contributed to the ability of the controller to give traffic advisories.

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Original NASA ASRS Text

Title: PWM TRACON Controller reported he observed a NMAC reported by an aircraft with an unidentified VFR target during a partial radar outage.

Narrative: I was working flight data during a busy and complex session where we were using 'multimode' radar rather than our usual Fusion mode. I heard a pilot on frequency that he was maneuvering to avoid a VFR aircraft. He then asked the Radar controller if a VFR target had been seen. The answer was no. I feel that due to the complexity and workload at the time it would have been difficult to see the traffic. After the incident happened I observed the VFR tag behind the regional jet. While observing over the next few minutes I saw an intermittent altitude readout of 8500 feet. I tagged up the target manually and asked if the adjacent Approach Control would continue to track the aircraft to see if we could get their perspective on the event.I think the complexity and added workload contributed to the controllers failure to give a traffic advisory. When the main radar site is out of service we go into multimode which requires us to coordinate departures and arrivals into and slows our automation as well as changes our radar quality and video display. We also had outages that involved frequently used radio frequencies creating a situation that required telephone calls to Center for coordination. All of this more labor intensive work takes away from our ability to watch the traffic on the screen and provide as good a service.Several hours later I was informed by our supervisor that the problem with the radar was not serious enough for our tech ops to work on it and that we should not have been in multimode for most of the day. I think there is a problem here because no one informed us about what the malfunction was; nor when it was fixed/determined to be not worthy of fixing. The status of the equipment was definitely not relayed as it should have been; causing higher workload and a higher potential for reduced attention and service; possibly reduced safety overall.I would recommend a review of the communication lines from the TRACON and tech ops and how information is relayed about equipment outages; especially when no one from tech ops is actually working. I wonder if sometimes TRACON calls TechOps; leave a message; and never follow up so nothing gets taken care of. I don't think the radar outage caused the NMAC; but it may have contributed to the ability of the controller to give traffic advisories.

Data retrieved from NASA's ASRS site 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.