Air carrier flight crew on RNAV approach noticed vertical information was not consistent with the ap...

Attributes
ACN	1318567
Time
Date	201512
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	Marginal
Light	Night
Aircraft 1
Make Model Name	Widebody Low Wing 3 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Route In Use	Other RNAV Approach
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Inflight Event / Encounter CFTT / CFIT

Narrative:

ILS xxl approach unavailable due to notam (inoperative). RNAV xxl approach. Vectored to final approach segment. Marginal weather above minimums. Crew recognized the profile data and the vdi were not consistent inside the final approach fix. Crew initiated go-around and advised tower. Tower advised 'low altitude alert' simultaneously. Crew returned after vectors for the same approach RNAV xxl to an uneventful landing. Crew debriefed the first and second approach. Overall; excellent team effort to identify the situation and go-around.RNAV approaches require 'cleared; established; and protected' guidance to perform properly. All of those criteria were met - however - inside the FAF; the crew recognized the data was improper with reference to the vdi. This discrepancy led to the decision to go-around and reset for another approach. The second approach performed with good data and no discrepancies.more proficiency training in the simulator and during normal operations on the line (choosing to practice these approaches more often). As always; if something isn't right or unstable -- go-around!

Original NASA ASRS Text

Title: Air carrier flight crew on RNAV approach noticed vertical information was not consistent with the approach. They executed a missed approach simultaneously with Tower advising a low altitude alert.

Narrative: ILS XXL approach unavailable due to notam (INOP). RNAV XXL Approach. Vectored to final approach segment. Marginal weather above minimums. Crew recognized the profile data and the VDI were not consistent inside the final approach fix. Crew initiated go-around and advised tower. Tower advised 'low altitude alert' simultaneously. Crew returned after vectors for the same approach RNAV XXL to an uneventful landing. Crew debriefed the first and second approach. Overall; excellent team effort to identify the situation and go-around.RNAV approaches require 'cleared; established; and protected' guidance to perform properly. ALL of those criteria were met - however - inside the FAF; the crew recognized the data was improper with reference to the VDI. This discrepancy led to the decision to go-around and reset for another approach. The second approach performed with good data and no discrepancies.More proficiency training in the simulator and during normal operations on the line (choosing to practice these approaches more often). As always; if something isn't right or unstable -- Go-Around!

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.

Air carrier flight crew on RNAV approach noticed vertical information was not consistent with the approach. They executed a missed approach simultaneously with tower advising a low altitude alert.