B737 Next Generation Undifferentiated
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Flight Crew Last 90 Days 178; Flight Crew Total 12246; Flight Crew Type 2877
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Procedure
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.
While executing the RNAV RNP Z 35R in DEN our separation with the aircraft ahead decreased to 2.5 nm. Wind was from the north at 30 kts and we were southbound prior to the AR segment and the aircraft ahead was on the AR segment (crosswind). We flew speeds as assigned from ATC starting at 210 kts and decreasing to 170kts. Requested the visual from ATC but was denied. The Captain asked ATC about the 2.5 mile separation and they provided minimal explanation as to why it was less than 3. The Captain was Pilot Flying and completed the approach in visual conditions with the aircraft ahead in sight at all times.
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.