Narrative:

Contacted by company flight operations regarding issues with an rnp Z 16R approach. Due to ATC congestion; we received our requested rnp clearance close to and/or at if point clfff. Although loaded in the CDU; our proximity to the if caused an error in the computer execution of the approach. Recognizing the error and having my first officer try to reload the approach; I attempted to fly the approach; in VFR conditions; using the magenta line and step down altitudes. Having all traffic in sight; I continued on the arc. Not wanting to put the aircraft in a position too close to an aircraft on runway 16L; I began to tighten the arc; thus going inside the parameters between points jarbo and jetsn. With the runway in sight and cleared to land I intercepted final approach path and landed on runway 16R while flying VFR. First of all; I should have recognized that when the approach parameters were not properly loaded in the computer at the time of if (initial approach fix) I should have notified ATC; requested vectors and shot a VFR approach. Secondly; we should have anticipated that the lack of approach clearance so close to the clfff would create compounding issues. Although ATC communications were congested; we should have notified ATC at the first indication of a problem instead of trying to fly the approach in a VFR manner. Lastly; and most importantly; I recognize that when cleared for an instrument approach; no matter if all conditions are VFR; I must comply with all instrument procedures to include altitude/airspeed and course parameters. Future flights will have those requirements at the top of my list.

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Original NASA ASRS Text

Title: B737-700 Captain reported a track deviation occurred on the RNP Z 16R Approach in DEN following an FMC error.

Narrative: Contacted by Company Flight Operations regarding issues with an RNP Z 16R Approach. Due to ATC congestion; we received our requested RNP clearance close to and/or at IF point CLFFF. Although loaded in the CDU; our proximity to the IF caused an error in the computer execution of the approach. Recognizing the error and having my First Officer try to reload the approach; I attempted to fly the approach; in VFR conditions; using the magenta line and step down altitudes. Having all traffic in sight; I continued on the arc. Not wanting to put the aircraft in a position too close to an aircraft on Runway 16L; I began to tighten the arc; thus going inside the parameters between points JARBO and JETSN. With the runway in sight and cleared to land I intercepted final approach path and landed on Runway 16R while flying VFR. First of all; I should have recognized that when the approach parameters were not properly loaded in the computer at the time of IF (Initial Approach Fix) I should have notified ATC; requested vectors and shot a VFR approach. Secondly; we should have anticipated that the lack of approach clearance so close to the CLFFF would create compounding issues. Although ATC communications were congested; we should have notified ATC at the first indication of a problem instead of trying to fly the approach in a VFR manner. Lastly; and most importantly; I recognize that when cleared for an instrument approach; no matter if all conditions are VFR; I must comply with ALL instrument procedures to include altitude/airspeed and course parameters. Future flights will have those requirements at the top of my list.

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.