Date: 201311
Local time of day: 1801-2400
Location: ZZZ.TRACON, US
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
ATC / advisory: TRACON ZZZ
Second aircraft: Super King Air 200
Reporter organization: Government
Reporter function: Approach; Departure
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness
Second reporter function: Departure; Approach
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
Result: General None Reported / Taken
Contributing factors: ATC Equipment / Nav Facility / Buildings; Human Factors
Primary problem: ATC Equipment / Nav Facility / Buildings

Narrative: As I took the position; I observed numerous arrivals inbound on the TSD plus strips and tab showing several departures divided between ZZZ; ZZZ1 and ZZZ2. Additionally; there were icing conditions in the immediate area requiring added transmissions to pass along and take pilot reports. I advised the Supervisor and said we should have another RADAR position opened. We changed over to the new Fusion RADAR within the last couple of weeks and it is much more difficult RADAR to work with. With FSL single sensor STARS you have an obvious perception of how fast targets are moving across the screen and with a quick scan of the RADAR can easily assess where to sequence aircraft and when to apply speed control. With Fusion RADAR you lose this capability. All targets update every second and it gives the appearance to the eye that jets are moving slower and the eye doesn't easily discern between their movement and that of a slower aircraft like a Cessna. This forces you to have to pay more attention to reading the tag to ascertain their speeds rather than the quicker method of an overview of the tag moving across the screen. It is especially time consuming when working higher volumes of traffic; so I felt a second scope would be a good idea. I ended up working the busy half hour session by myself. Leading the rush was a King Air 200 from the South. I asked him to keep his speed maximized as there were numerous jets coming in and there was a commercial jet behind him and a 737-800 from east that was much faster. As King Air 200 was getting within 20 NM he started slowing and said he'd be around 180 KTS. The 737-800 was faster and I had started to widen him out and reduced him to 210; but with Fusion RADAR the King Air 200 was really looking slow and it looked like the 737-800 could make the slot ahead of the King Air; so turned him back toward the slot and let him keep the 210 speed. Unfortunately the way fusion depicts the RADAR it was hard to tell how fast he was turning and at the very end the two aircraft were coming together faster than initially appeared. So I turned the King Air out to west; but ended up with 2.08 NM between them. Controllers from another facility were visiting and were complaining of the same problems with Fusion and that they didn't like it either. While Fusion does have the advantage of being able to work larger areas of airspace that cover 2 ASR sites; it's method of updating targets is not beneficial in busier traffic for working aircraft using the part of the brain that quickly correlates visual movement of the targets. When using Fusion if you put the 'headlight' (multifunction R) on an aircraft and give it a turn the headlight stays stationary for most of the turn then leaps at the end to the aircraft a new heading as opposed to a more fluid motion in single sensor. Recommendation; it is my opinion that Fusion is an inferior RADAR to single sensor FSL on the ASR-9 for working final approach. While Fusion may be fine for working larger areas of space; like combining west sector with [another] sector; it is not optimal for running a busy final. I recommend that single site ASR-9 FSL RADAR be used as the primary RADAR choice whenever the RADAR site is available and Fusion used as a backup and for working with combined sectors of [one TRACON] and RADAR West where coverage is required from two separate RADAR sites to span the airspace


Second narrative: I was instructed to open another sector to alleviate the RW Controller of a possible impending surge of traffic. I was in the process of opening and configuring my sector and then doing my two minute pre-monitoring of the position. When I observed the current traffic situation; I did notice that one of the aircraft was a King Air 200 straight in from the south which would warrant priority handling. The other aircraft I observed were a 737-800 airliner on the northeast arrival; a CRJ-900 on the southeast arrival and another airliner that was clearly number 4 on the west STARS arrival. From what I observed before I was about to initiate a position briefing; the RW Controller did not appear to have the aircraft in a position to allow the Medevac King Air 200 any undue delay to the airport. The King Air 200 was indicating around 220-230 KTS and all of the other aircraft were doing 300+ KTS. Making the situation worse was the southeast arrival was still straight in from the southeast with no vector or use of speed control less than 10 miles behind the Medevac aircraft. I wasn't comfortable taking the position yet; so I came off the relief briefing line and also because other aircraft started to check on at the northeast arrival. The RW Controller now was scrambling to fix the sequence and thought he/she could make the 737-800 number 1 (who was already on a natural downwind but should have been slowed) and turned the aircraft to a base inside the Medevac King Air 200 and descended to 30 which was also the altitude he/she had the Medevac aircraft descending to but didn't adjust the King Air 200's vector for spacing; also the SE arrival aircraft had to be turned to the west to now be properly sequenced to be number 3. The 737-800 did not turn as sharply as the RW Controller had expected and the separation was starting to decrease between him and the Medevac and so the CIC told the RW controller to turn the 737-800 more and the Controller complied and then also turned the Medevac aircraft to the left but the separation had now already decreased to the required 3 miles.


Synopsis: TRACON Controllers described a loss of separation event claiming the Fusion RADAR equipment was one causal factor.