B737-700 flight crew reported a track deviation occurred on the RNAV rnp Z approach to 16R in den wh...

Narrative:

We were cleared the RNAV rnp Z 16R approach into den. Upon crossing clfff; and still maintaining LNAV/ VNAV path; I set '0's' in the altitude window. We were instructed to maintain 170 knots until the FAF. As the aircraft turned final (still maintaining LNAV/VNAV path and on autopilot) I noticed the aircraft drifting left of course. Prior to turning final; there was a crosswind from the right. As we turned final; the crosswind switched to the left. I assumed the aircraft automation was trying to correct for this sudden change in wind direction; so I let the aircraft continue to fly the approach. It was about then that tower queried if 'we still had runway 16R in sight?' and that he showed us left of course. The captain told the tower that we did have runway 16R in sight; and were on course. As pilot flying (PF); I ended up clicking the autopilot off to hand fly the approach. I have flown RNAV rnps; as well as this particular RNAV rnp Z 16R; countless times; and have never seen a course/lateral deviation like what occurred in this instance. Although there was a shift in crosswinds as the aircraft turned final; it was on speed; correctly configured; and displaying LNAV/VNAV path. As this is an RNAV rnp approach; I was hesitant to correct the course deviation by clicking off the autopilot and hand flying; as I am under the impression that the lateral and vertical guidance of the approach are to be strictly adhered to (thus; following the flight director). I can only conclude that there is a navigational; or operational; issue with this particular approach; as it was obvious that it was not maintaining correct lateral guidance.

Original NASA ASRS Text

Title: B737-700 flight crew reported a track deviation occurred on the RNAV RNP Z Approach to 16R in DEN when the autopilot appeared to have difficulty dealing with a wind shift.

Narrative: We were cleared the RNAV RNP Z 16R Approach into DEN. Upon crossing CLFFF; and still maintaining LNAV/ VNAV PATH; I set '0's' in the altitude window. We were instructed to maintain 170 knots until the FAF. As the aircraft turned final (still maintaining LNAV/VNAV PATH and on autopilot) I noticed the aircraft drifting left of course. Prior to turning final; there was a crosswind from the right. As we turned final; the crosswind switched to the left. I assumed the aircraft automation was trying to correct for this sudden change in wind direction; so I let the aircraft continue to fly the approach. It was about then that Tower queried if 'we still had Runway 16R in sight?' and that he showed us left of course. The Captain told the Tower that we did have Runway 16R in sight; and were on course. As Pilot Flying (PF); I ended up clicking the autopilot off to hand fly the approach. I have flown RNAV RNPs; as well as this particular RNAV RNP Z 16R; countless times; and have never seen a course/lateral deviation like what occurred in this instance. Although there was a shift in crosswinds as the aircraft turned final; it was on speed; correctly configured; and displaying LNAV/VNAV PATH. As this is an RNAV RNP Approach; I was hesitant to correct the course deviation by clicking off the autopilot and hand flying; as I am under the impression that the lateral and vertical guidance of the approach are to be strictly adhered to (thus; following the flight director). I can only conclude that there is a navigational; or operational; issue with this particular approach; as it was obvious that it was not maintaining correct lateral guidance.

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	1580582
Time
Date	201809
Local Time Of Day	1801-2400
Place
Locale Reference	DEN.Airport
State Reference	CO
Environment
Light	Night
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	STAR PEEKK 3
Flight Plan	IFR
Person 1
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 323
Person 2
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 357
Events
Anomaly	Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types Inflight Event / Encounter Weather / Turbulence

B737-700 flight crew reported a track deviation occurred on the RNAV rnp Z approach to 16R in den when the autopilot appeared to have difficulty dealing with a wind shift.