Date: 202012
Location: DEN.Airport, CO
Flight conditions: VMC
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B D01
ATC / advisory: Center ZDV; TRACON D01
Reporter organization: Air Carrier
Reporter function: Captain
Human factors: Confusion; Communication Breakdown; Situational Awareness; Human-Machine Interface; Workload; Time Pressure
Second reporter function: Pilot Not Flying; First Officer
Anomaly: ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Observer; Person Air Traffic Control; Person Flight Crew
Result: Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Chart Or Publication; Human Factors; Procedure; Software and Automation; Airspace Structure
Primary problem: Procedure

Narrative: Arriving DEN on the CLASH2 arrival from the southeast; I planned and briefed an easterly flow arrival to land 17R. ATIS advertised 17R; 16L; 16R ILS; visual and RNAV Z approaches. I briefed for the RNAV RNP Z 17R. The final point for the arrival was QWIKE intersection and I left a discontinuity between that QWIKE and the QWIKE point starting the RNAV RNP Z 17R. Denver Center gave us a clearance to descend via the CLASH2 arrival landing south.The PM (Pilot Monitoring) and I confirmed that that was what we briefed and the FMC was properly programmed. The PM checked on with DEN Approach and we were told to expect RNAV Z to 16R. The PM installed that approach and I briefed the new arrival points and crossing restrictions on the CLASH2 that coincided with that runway; which were now a west downwind; the final fix being CLFFF. I briefed the approach as well. We did the same thing; leaving a discontinuity between CLFFF on the arrival and CLFFF as the IAF on the approach. The PM pulled the landing data for 16R and we briefed the changes on the engine-out missed approach which was slightly different then 17R. Approximately EVRLY intersection as we were descending through FL180; DEN Approach then said runway change; expect visual or ILS (I can't remember) to 16L. I remember it was at FL180 because it coincided with the altimeter change and the need to verify that VNAV is still able to maintain. The PM installed runway 16L and I did a briefing for the ILS 16L. This changed the FMC to an east downwind; the same fixes as for runway 17R but I did not note the changes in arrival fixes. As we were approaching JURKY intersection; I noticed on the FMC that the next waypoint was not what I was expecting. I had in my mind that we would be on a west downwind for the 16 runways. I said to the PM; it's not the correct fix next for runway 16R. The PM then asked DEN Approach to verify the runway assignment.Approach responded with a frequency change but did not respond to the request for runway clarification. This was at the point where we needed to go left or right depending on the runway. I thought it was 16R; so I went to the next fix for that runway; ROOTZ. As soon as the PM checked on with the next frequency; the Controller asked our runway assignment. The PM said we were trying to clarify. Approach then gave us 16R as a runway assignment. In fact; the previous clearance was for runway 16L. And that runway is an east downwind; not a west downwind even though the runway is on the west side of the airfield. This was absolutely my responsibility to ensure the correct runway and corresponding waypoints for the arrival. Going forward my personal correction will be to write down the runway assignment given by ATC each time it changes; whether on the yoke clip notepaper or on the iPad graphic. I also got complacent after doing 2 full briefings into DEN on a clear day. With the 3rd briefing; I did an abbreviated briefing. A full briefing; stepping through every arrival point would have caught it earlier. Additionally; as suggested by the Jump Seater; instead of clarifying the runway and having to verify the points quickly; I will ask ATC for the next waypoint they are expecting in order to give myself some time to figure out any ambiguities between the FMC and the chart. If we are adding to the data for DEN arrival deviations though...I didn't think this could happen to me. We briefed the threat of runway changes going into DEN. But DEN giving runway changes that impact arrival points without sufficient time for us to properly program and confirm was a contributing factor. Its 11.4 miles from EVRLY where we got the change to JURKY where the arrival splits. To reprogram; confirm; brief; get landing data and brief the engine-out profile changes while monitoring the descent is challenging.


Second narrative: CLASH2 RNAV into DEN we initially planned for a Visual Approach to 17R backed up by the ILS. Initial Controller told us to expect 16R so we loaded RNAV/RNP 16R with the CLFFF transition to the approach; per ATIS. Cleared to descend via the CLASH2 arrival so we set 11;000 feet in the MCP (Mode Control Panel). ATC then advised us to expect Visual Approach to 16L. I then loaded the 16L ILS in the box and the Captain continued the descent on the arrival around the JURKEY fix. When the Captain started to brief the new arrival she noticed the arrival fixes did not match up with the new runway.I asked ATC to verify our runway assignment as all 3 of us in the cockpit were unclear at that point. After a pause; ATC gave us a new frequency instead of answering my query regarding which runway. At that point the Captain manually entered the ROOTZ fix. We changed our altitude in the MCP to correspond to the 13;000 feet minimum at ROOTZ while we checked in with the final Controller. Upon checking in the Controller asked us which runway we were planning on. I asked again which runway as we were not certain at that point. He then stated Visual Approach 16R. I updated the box AGAIN to the ILS 16R and; we were then given a heading and new altitude. The rest of the arrival and approach were uneventful.


Synopsis: Air carrier flight crew reported they deviated from the assigned route due to last minute runway changes and incomplete communications from ATC during arrival to DEN airport.