B737-800
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Flight Crew Last 90 Days 501; Flight Crew Type 11195
Human-Machine Interface; Situational Awareness
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Altitude Undershoot; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Human Factors
We planned for the Visual to Runway 16L and talked about the possible assignment to 17R. When checking in with Approach we were advised to expect 17R. We briefed and programmed the RNP Z 17R. AS we approached the IAF I was preparing for what to do (i.e. what fix to use based on location of active waypoint) and/or the state of the IAF (i.e. active waypoint or not). To the best of my recollection; the IAF was on LSK L2; then I placed it IAF under IAF; although a review after the fact stated we 'could' place in on top of it. We both complied with VVMI prior to execution. The aircraft continued on downwind with no descent. Almost simultaneously; as we noticed the wrong picture on the MAP display; the Controller asked us if we were descending. By this time I had disconnected automation and was following the purple line while both of us were monitoring altitude restrictions based on our clearance. The Pilot Monitoring reprogrammed the approach and the rest of the flight was uneventful. No further calls from ATC; altitude; or course deviations occurred. Consider calling the field in sight and requesting visual approach. We do believe that the IAF (since we were close to it) might have auto-sequenced from L2 to L1 (active); and as we know the programming in this case would have been different. Therefore; maybe a closer look at the distance remaining to the active waypoint might have helped prevent this situation.
B737 MAX8 Captain reported failure to descend as charted while flying the RNAV (RNP) Z approach to Runway 17R at DEN due to an FMC programming error.