Date: 202007
Location: DEN.Airport, CO
Flight conditions: VMC
Aircraft: Widebody Transport
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B DEN
ATC / advisory: Center ZDV
Second aircraft: Large Transport
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Distraction
Second reporter function: Pilot Not Flying; First Officer
Anomaly: ATC Issue All Types; Conflict NMAC
Detector: Automation Aircraft RA; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Inbound to Denver on the LAWGR1 arrival; Denver center switched us to the AALLE1 arrival due to congestion. Descend via the arrival; runway 17R. Fine. We're already in the descent; we got this. Told to proceed to HEDDD but slow NOW to 250kts (early). He stuck [another] flight [Aircraft Y] past us and in front of us. Welcome to Denver. Then further slowed to 210 and call arrival. Okay. We made all the restrictions.Approach assigns us 16L. Okay. No heavies on 17R. Okay. Why didn't center know that? That's a lot of programming and briefing so close in. We managed. The controlled vectored the previous [flight] in front of us and pressed him to take a visual and keep his speed up. We were cleared to intercept the LOC but maintain 10000'. Slightly high but okay. Then a step down to 9000 right at KUURT; etc.... Pressed him for lower as we already were a dot high. 'Traffic converging on the right below you for 16R. Okay; could not see him. He FINALLY cleared us for the ILS; thankfully we were slow so making up for being high was not going to take us out of stable approach criteria. Switched us to tower.The second I got the clearance for the ILS I disconnected the AP & AT and started down to catch the glide before the 1000' point. AT the same time we received an RA to 'level off'. I complied with the visual guidance on the ADI while the PM (Pilot Monitoring) was looking for the traffic on our right. They were [Aircraft Z].He had overshot the final for 16R and encroached on our final somewhere below us. Reported the RA to the tower. They replied 'what do you want to do'. The RA ceased and we agreed it was safe enough to continue a visual approach which we requested and received clearance for. We safely met all of the stable approach criteria and landed without further incident. We were never told by tower or approach that the parallel traffic has encroached our safety zone.Contributing factors were jammed spacing on final by putting [Aircraft Y] (who was behind us) ahead of us and keeping us high because we got too close to him on final as well as having two separate final frequencies for approach for 16R & L. The encroaching flight was a problem in itself.


Second narrative: DEN approach cleared us for AALL1 RWY 17R transition. We had planned the 16L approach. Prior to the approach transition on the arrival they re-cleared us for the 16L transition because they said 17R can't land Heavy Jets. Reset up for 16L with plenty of time and re-breifed the approach which we had originally planned. We were kept high and slowed to accommodate traffic they put in front of us; [Aircraft Y]. We were given several turns and told to intercept LOC 16L. I had to ask for lower 2 times while on the localizer because we were about to fly through the glide slop. On the 2nd query I also reported airport in site. We were at 8000 just prior to KIKME when DEN approach cleared us for the visual and switched us to tower. The Captain engaged the approach mode and we did the rest of our SOPs. After switching tower told us about [Aircraft Z] low and to our right landing RWY 16R. I reported the traffic in site. At the same time I told the Captain he was not a factor. But as we came down the glide slope and tracking 16L LOC [Aircraft Z] seemed to be getting closer than I thought it should be. About the time I was going to say something to the Captain and ATC tower; we go the RA and was told to level off. This happened about 1500 AGL. The Captain leveled the AC and I reported to tower we were responding to an RA. The RA lasted less the 10 seconds. I could see [Aircraft Z] correcting back to the right and said we were clear to the Captain. The RA stopped; tower asked our intentions. The Captain said to continue. I told tower we would continue the approach. We were stable and on speed by 1000 AGL.


Synopsis: Air Carrier flight crew reported an NMAC event during final approach due in part to ATC aircraft traffic sequencing as well as late runway change.