Date: 201605
Local time of day: 1801-2400
Location: U90.TRACON, AZ
Light: Night
Aircraft: Military Transport
Operator: Military
Operating under: Part 91
Flight plan: IFR
Flight phase: Initial Approach
Airspace: Class E U90
ATC / advisory: TRACON U90
Second aircraft: Military Transport
Reporter organization: Government
Reporter function: Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness; Communication Breakdown; Confusion; Distraction; Troubleshooting; Workload
Anomaly: ATC Issue All Types; Conflict NMAC; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Flight Crew Took Evasive Action
Contributing factors: Human Factors; Procedure
Primary problem: Procedure

Narrative: I was working all sectors combined; traffic volume and complexity was low. Aircraft Y conducting PARA jumps over MZJ at 10;000 ft. Aircraft X inbound from the NW of MZJ level at 11;000 ft to pass safely above the jump zone. Jumps commenced SW of MZJ without incident and Aircraft Y descended; when leaving approximately 4;300 ft radar service was terminated and the data tag was put in track suspend because they were making multiple jumps. The data tag dropped off the scope around 3;300 ft and I assumed Aircraft Y landed at MZJ until the suspended target acquired approximately 10 miles SE of MZJ near AVQ airport. The suspended target dropped off and acquired a few times near AVQ and since it was a suspended data tag there was no altitude readout displayed. Aircraft X was on a 100 degree heading to intercept the TACAN final RY12 DMA level at 5;000 ft when the collision alert sounded. I immediately issued a traffic alert to Aircraft X on the VFR target (who was Aircraft Y; the aircraft terminated 10-15 miles west near MZJ). At the time of the traffic alert; I was unable to immediately assess whether the VFR target was climbing; level; descending; etc. so initially I did not recommend an alternate course of action for Aircraft X. After watching the replay the VFR target; (Aircraft Y) had conducted a high speed low passes over AVQ and was in a hard left turn and climbing rapidly directly at Aircraft X. Aircraft X responded to the TCAS RA; he had to descend rapidly and turn to avoid collision. After Aircraft X returned to his previously issued heading and altitude; I called out in the blind to see if Aircraft Y was monitoring my frequency; which he was and I questioned why he was so far from MZJ and conducting abrupt maneuvers in that area. The pilot said he was setting up for an approach at MZJ. Aircraft X completed the approach and I was relieved from position. On climb-out after the TACAN approach Aircraft X requested a full stop and advised the controller they would be filing a NMAC report. The only thing that would have helped me assess the situation earlier and issue the traffic earlier; which may or may not have prevented this situation because of the abrupt maneuvers conducted by Aircraft Y; would be an altitude readout on the suspended data tag. Once the data tag is suspended; there is no information displayed. I feel it could have possibly helped me to make a decision sooner.




Synopsis: Tucson TRACON (U90) Controller reported of a near-mid-air-collision due to an aircraft making abrupt maneuvers. The aircraft in question had a suspended transponder and did not show an altitude. Pilot of normal aircraft reported of NMAC to another Controller.