Air carrier flight crew reported an near midair collision event during final approach due in part to...

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 localizer 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 & left. The encroaching flight was a problem in itself.

Original NASA ASRS Text

Title: 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.

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.

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.

Attributes
ACN	1753352
Time
Date	202007
Place
Locale Reference	DEN.Airport
State Reference	CO
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	Widebody Transport
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Large Transport
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Flight Plan	IFR
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument
Experience	Flight Crew Last 90 Days 28 Flight Crew Total 10073 Flight Crew Type 7289
Person 2
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	ATC Issue All Types Conflict NMAC

Air carrier flight crew reported an near midair collision event during final approach due in part to ATC aircraft traffic sequencing as well as late runway change.