Date: 201906
Local time of day: 1201-1800
Location: D01.TRACON, CO
Light: Daylight
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B DEN
ATC / advisory: TRACON D01
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Time Pressure; Communication Breakdown; Situational Awareness
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Detector: Automation Aircraft RA
When detected: In-flight
Result: Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Contributing factors: Human Factors; Procedure
Primary problem: Human Factors

Narrative: We were initially arriving on PEEKK 3 into DEN; expecting RNAV Z 16R. STAR changed to CREDE 3 with descend via. We descended via to 11;000 ft. at CLFFF with points GREYS then HIMAY. There was a discontinuity then CLFFF and the approach points for RNAV Z 16R. Initial DEN Approach was busy; seemed rushed and behind with other inbound aircraft prompting for clearance info for their approaches. Once I thought I heard two different voices and we discussed possible training or evaluation. We were switched to a second DEN Approach [frequency] just outside of CLFFF without clearance for approach. We were immediately given clearance for RNAV Z Runway 16R when we checked on. I; PF; thought I put CLFFF from the approach at top of page on top of arrival CLFFF to close discontinuity and activate the RNAV approach. I verbalized and verified prior to execution. As we approached CEPEE; I noticed and verbalized my concern that we weren't starting to descend. My PM noticed the magenta line was still drawn from CLFFF to GREYS and HIMAY. I immediately went to heading mode to initiate right turn to arc towards AAGEE and the PM input the correction into the FMS for the approach. We appeared to be right on top of CEPEE and just initiated a turn and thought we had it corrected in time when Approach Control questioned us. He broke us off the RNAV for radar vectors and gave us phone number for possible pilot deviation. He vectored us out with a couple of turns; speed restrictions and descents. On the final vector past NEWLN he cleared us to intercept ILS 16R with an altitude restriction for NEWLN. We didn't have this approach set up and were not given what to expect by Approach; while being vectored. We had the ILS set as a backup but still had to enter approach in the FMS and manually enter NEWLN; under a rushed situation. We were cleared the approach and speed 170 until JETSN. Inside NEWLN we got a TA and the PM saw (other carrier) aircraft to our left on a parallel approach to 16L. We continued; and then got an RA. I disconnected the A/P and leveled off as the RA advised. Then we got a climb RA and I climbed in accordance to the RA. The PM was able to keep the traffic in sight and determined we could continue as we continued to configure for landing. I was able to descend and continue to a stabilized approach and landing for 16R. The PM advised either Approach or Tower of the TA/RA.




Synopsis: B737-800 First Officer reported a track deviation occurred on an RNAV arrival into DEN following multiple clearance changes from ATC.