Date: 201703
Local time of day: 1201-1800
Location: DEN.Airport, CO
Aircraft: Widebody Transport
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Descent
Airspace: Class B DEN
ATC / advisory: TRACON D01
Second aircraft: A320
Reporter organization: Government
Reporter function: Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Confusion; Situational Awareness; Human-Machine Interface; Distraction
Second reporter function: Approach
Anomaly: Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action
Contributing factors: Human Factors; Procedure; Airport; Equipment / Tooling
Primary problem: Equipment / Tooling

Narrative: I was training on FR2 and we were working runway 16L. There was a separate controller that was working runway 16R and another that was working runway 17R. We were just taking the briefing and the relieved controller told us Aircraft X was on a heading to join the Localizer (LOC) and on a visual clearance but traffic had not been passed for the parallel final on runway 16R. The first transmission my trainee made was to call traffic. When Aircraft X got near the LOC he said he was responding to a TCAS/RA and going around. He started a slow climb and ended up shooting through the 16L LOC and ended up almost directly on top of Aircraft Y who was established on the 16R LOC. They were only a few hundred feet separated vertically. We allowed Aircraft X to recover and then gave him instructions. My assumption is that when Aircraft X received the RA the pilot grabbed the yoke and pulled back which disengaged the autopilot so the aircraft was no longer going to intercept the LOC for 16L. In this case the pilot's response to the RA actually made it less safe because he overshot his LOC and ended up so close to other traffic.Aircraft X was only about 10 miles from touchdown and a little less than 3000 feet AGL when he got the RA. I understand that they are trying to be as safe as possible but when aircraft are that close to the airport the RA response was less safe than if he had joined the LOC. On 16L/R aircraft get consistent RAs from parallel traffic. I think that we either need to land runways that are further apart at DEN when we land south to avoid this constant safety risk. If we do not do that then the airlines need to allow the pilots to go into advisory mode higher and further from the field. If we have an RA 20 miles out and at 10;000 feet then we have options but when they are so close to the field and almost down to our Minimum Vectoring Altitude we are left to do nothing but watch and call traffic.


Second narrative: Final was split between the 251 and 252 positions. I was 251 and working the A320 to RWY 16R. The 252 position was working the 'heavy' to RWY 16L. My A320 was vectored to final to stay above the 'heavy' and cleared for the VA legally. The 'heavy' was also vectored to final and cleared for the VA legally. The 'heavy' joined final on a heading that was converging with my A320 who was already on final. The A320 reported the 'heavy' in-sight and was shipped to the tower. Seconds later the 'heavy' reports responding to an RA and flies through the localizer and over the top of the A320 by an estimated 400-700 feet. All procedures were executed properly and safely in my opinion.This sort of event happens frequently at Denver because the preferred runway configuration when we're landing south are the 16's. These runways are 2800 feet apart and frequently result in RA's and TCAS events; this is especially true with less familiar aircraft. In my opinion the runways are too close to be the preferred runways for VA's and we should be landing aircraft to one of the 16's and both of the 17's when we're using three runways and one of the 16's and one of the 17's when we're only at a two runway rate.


Synopsis: D01 TRACON controllers reported that an aircraft on final that was using visual separation on an adjoining aircraft went around due to a Resolution Alert. This made the scenario worse because the aircraft was heavy and flew over another aircraft.