Narrative:

We were on the anchr 4 arrival into denver. We originally briefed and set up for the ILS 35R approach. As we were descending through FL180 ATC informed us to expect the RNAV approach to runway 35R. I was the monitoring pilot and I loaded the approach into the FMC. I noticed that there were two possible transitions for the approach but did not load one at that time. My thought process was that we would get cleared the approach via fix and altitude and we would have plenty of time to load the proper transition into the FMC for the approach. The first officer briefed the RNAV 35R approach and referenced the approach briefing guide for RNAV approaches. We were flying the arrival and we were at 11000 ft. We passed the initial fix doggg which is on the arrival but also one of the initial fixes for the approach without an approach clearance. Since there was not a transition selected in the FMC the active waypoint in the FMC was dontt on the anchr 4 arrival. Just prior msims we were cleared for the approach. Right after ATC cleared us for the approach; he informed me that there is a lot of background noise when I key the mic to respond to clearance. I selected the approach and transition to proceed on the approach. I was not able to get the legs page sequenced before passing msims. Right after passing msims we noticed the aircraft was not descending on the VNAV path and it was not turning. I tried to sequence the legs page to keep us on the approach while the first officer tried to keep us on the VNAV path for the approach. ATC then said that we missed the turn and asked if our FMC is engaged. I responded that yes it is engaged and we have fixed the issue and we are in the turn. He then gave us a heading and cleared us for the ILS runway 35R. I loaded the ILS 35R into the FMC and we flew that approach. We taxied to the gate and debriefed.

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Original NASA ASRS Text

Title: B757 Captain reported a track deviation occurred following a late clearance to fly the RNAV approach to DEN RWY 35R.

Narrative: We were on the ANCHR 4 Arrival into Denver. We originally briefed and set up for the ILS 35R Approach. As we were descending through FL180 ATC informed us to expect the RNAV approach to Runway 35R. I was the monitoring pilot and I loaded the approach into the FMC. I noticed that there were two possible transitions for the approach but did not load one at that time. My thought process was that we would get cleared the approach via fix and altitude and we would have plenty of time to load the proper transition into the FMC for the approach. The First Officer briefed the RNAV 35R Approach and referenced the approach briefing guide for RNAV approaches. We were flying the arrival and we were at 11000 ft. We passed the initial fix DOGGG which is on the arrival but also one of the initial fixes for the approach without an approach clearance. Since there was not a transition selected in the FMC the active waypoint in the FMC was DONTT on the ANCHR 4 Arrival. Just prior MSIMS we were cleared for the approach. Right after ATC cleared us for the approach; he informed me that there is a lot of background noise when I key the mic to respond to clearance. I selected the approach and transition to proceed on the approach. I was not able to get the legs page sequenced before passing MSIMS. Right after passing MSIMS we noticed the aircraft was not descending on the VNAV path and it was not turning. I tried to sequence the legs page to keep us on the approach while the First Officer tried to keep us on the VNAV path for the approach. ATC then said that we missed the turn and asked if our FMC is engaged. I responded that yes it is engaged and we have fixed the issue and we are in the turn. He then gave us a heading and cleared us for the ILS Runway 35R. I loaded the ILS 35R into the FMC and we flew that approach. We taxied to the gate and debriefed.

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.