Narrative:

We were on descent into den and had been cleared while still on the arrival for the RNAV Z 16R starting at clfff. As we made the arcing turn after jabro we were advised by ATC of traffic to the parallel 16L and quickly spotted the traffic visually as well as on TCAS. The weather was VMC and the traffic and field were in sight. Per procedure we changed the TCAS to TA only. As we got a little closer it was apparent that we were going to join over jetsn and be right next to the traffic. I turned the autopilot off and told the captain that I would like to start a slightly early turn to make sure we didn't overshoot the final at all. I realize the rnp approaches are very; very good and that the aircraft flies the course extremely well; but I have seen small deviations that are still inside required anp and I just thought it would be wise to very much make sure we didn't overshoot. My intent was to stay just a little right but still inside the course corridor; but with looking at the traffic and at the runway I must have ended up just a little farther right than planned at jetsn. The captain and I briefly discussed the approach afterward and decided that given the traffic it was the safest course of action. I know now that it would have been better to not have made a course deviation; or requested a visual approach once we perceived the situation. This was a good learning experience for me; and I'm grateful that the ATC team reached out to help me understand the situation better. I really value our rnp approach abilities and think the program is a huge safety asset and do not want to see it hindered in any way by my accidental non-compliance. I think given the same situation in the future; I would communicate my concern to ATC early and possibly ask for a visual approach clearance; or keep the automation all engaged and just monitor very closely for any signs of conflicts with the traffic. I also feel that we were a little set up for it by the almost exact lining up of the parallel traffic and our speed and spacing. I realize that it is completely fine and legal to space that way; but at night traffic distance can be hard to judge and it's difficult to spot if they have any course deviations. Again this was a good learning experience for me and has given me a lot of good information.

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Original NASA ASRS Text

Title: B737-700 flight crew reported deviating from the RNAV Z 16R charted track on arrival into DEN to avoid traffic lining up for the parallel Runway 16L.

Narrative: We were on descent into DEN and had been cleared while still on the arrival for the RNAV Z 16R starting at CLFFF. As we made the arcing turn after JABRO we were advised by ATC of traffic to the parallel 16L and quickly spotted the traffic visually as well as on TCAS. The weather was VMC and the traffic and field were in sight. Per procedure we changed the TCAS to TA only. As we got a little closer it was apparent that we were going to join over JETSN and be right next to the traffic. I turned the autopilot off and told the Captain that I would like to start a slightly early turn to make sure we didn't overshoot the final at all. I realize the RNP approaches are very; very good and that the aircraft flies the course extremely well; but I have seen small deviations that are still inside required ANP and I just thought it would be wise to very much make sure we didn't overshoot. My intent was to stay just a little right but still inside the course corridor; but with looking at the traffic and at the runway I must have ended up just a little farther right than planned at JETSN. The Captain and I briefly discussed the approach afterward and decided that given the traffic it was the safest course of action. I know now that it would have been better to not have made a course deviation; or requested a visual approach once we perceived the situation. This was a good learning experience for me; and I'm grateful that the ATC team reached out to help me understand the situation better. I really value our RNP approach abilities and think the program is a huge safety asset and do not want to see it hindered in any way by my accidental non-compliance. I think given the same situation in the future; I would communicate my concern to ATC early and possibly ask for a visual approach clearance; or keep the automation all engaged and just monitor very closely for any signs of conflicts with the traffic. I also feel that we were a little set up for it by the almost exact lining up of the parallel traffic and our speed and spacing. I realize that it is completely fine and legal to space that way; but at night traffic distance can be hard to judge and it's difficult to spot if they have any course deviations. Again this was a good learning experience for me and has given me a lot of good information.

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.