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B767 first officer and relief pilot reported executing a go-around at ewr when the autopilot failed to track the vertical path accurately.
| Attributes | |
| ACN | 1589122 |
| Time | |
| Date | 201810 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | EWR.Airport |
| State Reference | NJ |
| Environment | |
| Flight Conditions | IMC |
| Aircraft 1 | |
| Make Model Name | B767 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Final Approach |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Autoflight System |
| Person 1 | |
| Function | Pilot Not Flying First Officer |
| Qualification | Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Instrument |
| Experience | Flight Crew Last 90 Days 150 Flight Crew Type 1470 |
| Person 2 | |
| Function | Pilot Not Flying First Officer Relief Pilot |
| Qualification | Flight Crew Instrument Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 199 Flight Crew Type 3272 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Inflight Event / Encounter Unstabilized Approach Inflight Event / Encounter Weather / Turbulence |
Narrative:
Ewr had low ceilings and shifting winds. The 4R was out of service; and RNAV approaches were advertised on the ATIS. We prepared and briefed the RNAV (rnp) Z 4R; as the minima were lowest; to better ensure seeing the runway at or before minimums. The autoflight and VNAV functions worked normally until passing the FAF. Upon passing the FAF; and as the winds aloft were shifting towards a headwind; VNAV pth remained displayed; however the aircraft did not descend; despite touchdown zone altitude being set in the altitude window; per procedure. Indeed; all 3 of us noted that the captain pfd showed us as being below the vertical path; whereas mine showed being above. The vertical path deviation indicators rapidly diverged and the aircraft remained at 1700 ft as we progressed toward the runway. This was obviously unacceptable; exceeding tolerances; and as such we elected to conduct a missed approach and informed ATC. We subsequently briefed and flew the ILS 4R GS out of service; using localizer and VNAV. This approach was uneventful.
Original NASA ASRS Text
Title: B767 First Officer and Relief Pilot reported executing a go-around at EWR when the autopilot failed to track the vertical path accurately.
Narrative: EWR had low ceilings and shifting winds. The 4R was out of service; and RNAV approaches were advertised on the ATIS. We prepared and briefed the RNAV (RNP) Z 4R; as the minima were lowest; to better ensure seeing the runway at or before minimums. The autoflight and VNAV functions worked normally until passing the FAF. Upon passing the FAF; and as the winds aloft were shifting towards a headwind; VNAV PTH remained displayed; however the aircraft did not descend; despite touchdown zone altitude being set in the altitude window; per procedure. Indeed; all 3 of us noted that the Captain PFD showed us as being below the vertical path; whereas mine showed being above. The vertical path deviation indicators rapidly diverged and the aircraft remained at 1700 FT as we progressed toward the runway. This was obviously unacceptable; exceeding tolerances; and as such we elected to conduct a missed approach and informed ATC. We subsequently briefed and flew the ILS 4R GS out of service; using LOC and VNAV. This approach was uneventful.
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.