Date: 201807
Local time of day: 1201-1800
Location: DEN.Airport, CO
Light: Daylight
Aircraft: B737-700
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B DEN
ATC / advisory: Tower DEN
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Situational Awareness
Anomaly: Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Human Factors; Procedure
Primary problem: Human Factors

Narrative: Our flight to DEN brought us in on the PEEKK 3 RNAV Arrival which usually results in an RNP approach to 16R; which we briefed and planned. When Denver Approach cleared us for the RNAV Z 16R; as the Pilot Monitoring I observed the Captain close the FMS flight plan's discontinuity at CLFFF; resulting in a seamless transition from the arrival to the approach. He selected 7000 ft in the MCP altitude window when cleared for the approach and subsequently selected 0000 ft in the MCP altitude window when we passed CLFFF; all in accordance with Company policy. While still communicating with Approach we were advised of traffic on the parallel runway; 16L. I called the traffic in sight and was given an instruction to contact Tower. At the time of this communication we were around the AAGEE waypoint and on the base leg of the RNP approach; and our nose was pointed at the traffic (a regional aircraft at our 12 o'clock position). While I contacted Tower; the Captain verbalized disconnecting the autopilot/autothrottles and his intention to fly a dogleg to final in order to preempt a conflict with the regional aircraft. He turned away from the traffic and hand-flew an intercept to final. Tower cleared us to land; we continued to configure the aircraft normally and landed on 16R uneventfully. We did not receive any TCAS notifications; nor did Tower or Ground inform us of any possible deviation. The lateral deviation from the RNAV approach course occurred in daytime VMC conditions with the airport and conflicting traffic in sight. We were behind the reported traffic; he remained in front of us on his approach the entire time. The Captain's actions were intended to avoid a conflict; I can assert this as he verbalized as much to me while exercising the VVMI methodology we are taught at Company. As I understand; our actions to cut the corner and attempt to separate ourselves from the reported traffic resulted in a loss of separation event. This occurred while we were in VMC conditions and talking to the Control Tower. I recommend specific scenario-based training to [flight crews] to continue to fly the lateral course of any approach after being cleared (even in VMC); as I thought we were well within our rights to do what we did.




Synopsis: B737-700 First Officer reported a loss of separation occurred on the RNP approach to 16R at DEN when the Captain deviated from the charted course to increases separation from an aircraft on the 16L approach.