B737NG flight crew reported that while flying the RNAV rnp Z approach to 35R at den the separation t...

Attributes
ACN	1606621
Time
Date	201812
Place
Locale Reference	DEN.Airport
State Reference	CO
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	B737 Next Generation Undifferentiated
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Flight Plan	IFR
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument
Experience	Flight Crew Last 90 Days 178 Flight Crew Total 12246 Flight Crew Type 2877
Person 2
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Instrument Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 152 Flight Crew Type 540
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Published Material / Policy

Narrative:

On arrival into den; we were given a STAR to the RNAV 35R approach with the radius turn. Our speed was controlled by ATC even after approach clearance. It was apparent the aircraft in front of us slowed early and ignored ATC speeds; as we had a closure on the aircraft in front. Our VNAV system and the 'required' autopilot on caused our speed changes to be much slower than if they were hand flown and this made the situation worse. The weather conditions were VMC; and we didn't have 3nm separation between the aircraft in front of us. We queried ATC and asked for a visual approach so we could adequately separate and comply with the approach procedures. They simply re-cleared us for the approach with no explanation. Tower was queried on the separation also and could not answer us. The landing was uneventful; but the limitations provided to us on the approach by both FM procedure and ATC; which were unnecessary in the conditions; combined to put us in a worse situation than if we had been given the freedom to maneuver. ATC training and execution at den is still inadequate to conduct these procedures; even in VMC conditions.

Original NASA ASRS Text

Title: B737NG flight crew reported that while flying the RNAV RNP Z approach to 35R at DEN the separation to the traffic ahead decreased to 2.5 miles; but ATC seemed unconcerned when advised.

Narrative: On arrival into DEN; we were given a STAR to the RNAV 35R Approach with the radius turn. Our speed was controlled by ATC even after approach clearance. It was apparent the aircraft in front of us slowed early and ignored ATC speeds; as we had a closure on the aircraft in front. Our VNAV system and the 'required' autopilot on caused our speed changes to be much slower than if they were hand flown and this made the situation worse. The weather conditions were VMC; and we didn't have 3nm separation between the aircraft in front of us. We queried ATC and asked for a visual approach so we could adequately separate and comply with the approach procedures. They simply re-cleared us for the approach with no explanation. Tower was queried on the separation also and could not answer us. The landing was uneventful; but the limitations provided to us on the approach by both FM procedure and ATC; which were unnecessary in the conditions; combined to put us in a worse situation than if we had been given the freedom to maneuver. ATC training and execution at DEN is still inadequate to conduct these procedures; even in VMC conditions.

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.

B737NG flight crew reported that while flying the RNAV rnp Z approach to 35R at den the separation to the traffic ahead decreased to 2.5 miles; but ATC seemed unconcerned when advised.