B737 first officer reported a track deviation occurred on the RNAV (rnp) Z approach to den after a l...

Narrative:

Prior to descent the RNAV (rnpz) for runway 35R was briefed and programmed into the FMC as the expected clearance. We discussed as a crew both options of 1) connecting the arrival and approach prior to actual clearance; creating the threat of a turn without clearance; or 2) leaving a discontinuity in the FMC which would be closed once clearance was received. During the arrival we received numerous speed changes and a relatively late clearance for the approach. As pilot flying (PF) I asked the pilot monitoring (pm) to close the discontinuity. I observed him working in the box and verified the change. Though I verified the change I was distracted with managing an assigned speed change and aircraft configuration and did not recognize that the FMC was not correctly sequenced. [A crosscheck] was performed and all appeared correct as the fmas for the arrival presented the same as they would for the approach (LNAV/VNAV path and a centered path indication on the nd). Upon arriving at the point beginning the RF leg the aircraft did not begin its turn and the FMC error became apparent. ATC queried us regarding our course and subsequently vectored us off the approach.

Original NASA ASRS Text

Title: B737 First Officer reported a track deviation occurred on the RNAV (RNP) Z Approach to DEN after a late clearance and failing to catch a discontinuity in the briefing.

Narrative: Prior to descent the RNAV (RNPZ) for Runway 35R was briefed and programmed into the FMC as the expected clearance. We discussed as a crew both options of 1) connecting the arrival and approach prior to actual clearance; creating the threat of a turn without clearance; or 2) leaving a discontinuity in the FMC which would be closed once clearance was received. During the arrival we received numerous speed changes and a relatively late clearance for the approach. As Pilot Flying (PF) I asked the Pilot Monitoring (PM) to close the discontinuity. I observed him working in the box and verified the change. Though I verified the change I was distracted with managing an assigned speed change and aircraft configuration and did not recognize that the FMC was not correctly sequenced. [A crosscheck] was performed and all appeared correct as the FMAs for the arrival presented the same as they would for the approach (LNAV/VNAV PATH and a centered path indication on the ND). Upon arriving at the point beginning the RF leg the aircraft did not begin its turn and the FMC error became apparent. ATC queried us regarding our course and subsequently vectored us off the approach.

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.

Attributes
ACN	1590594
Time
Date	201811
Local Time Of Day	1201-1800
Place
Locale Reference	DEN.Airport
State Reference	CO
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Flight Plan	IFR
Person 1
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Type 285
Events
Anomaly	ATC Issue All Types Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

B737 first officer reported a track deviation occurred on the RNAV (rnp) Z approach to den after a late clearance and failing to catch a discontinuity in the briefing.