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Boeing 737 captain reported erratic ILS course and glideslope indications while proceeding inbound in visual conditions.
| Attributes | |
| ACN | 1534849 |
| Time | |
| Date | 201804 |
| Local Time Of Day | 0001-0600 |
| Place | |
| Locale Reference | UAM.Airport |
| State Reference | GU |
| Environment | |
| Flight Conditions | VMC |
| Aircraft 1 | |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 91 |
| Flight Phase | Initial Approach |
| Route In Use | Direct |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | ILS/VOR |
| Person 1 | |
| Function | Pilot Flying Captain |
| Qualification | Flight Crew Instrument Flight Crew Flight Instructor Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine |
| Experience | Flight Crew Last 90 Days 100 Flight Crew Total 2500 Flight Crew Type 800 |
| Events | |
| Anomaly | ATC Issue All Types Deviation - Procedural Clearance Deviation - Track / Heading All Types |
Narrative:
When cleared for the ILS-6R into uam; the autopilot was used to intercept the final approach course while descending to our assigned altitude of 2700 feet MSL to intercept the glideslope. Shortly after localizer capture; the autopilot turned itself off and we noted some erratic ILS course and glideslope indications while proceeding inbound in visual conditions. While we were in the process of recognizing these incorrect ILS indications; the aircraft deviated slightly from the final approach course somewhere in the vicinity of the final approach fix. We corrected this deviation once we noticed it; but did [not] receive any glideslope indications until 600 feet AGL. We continued to receive localizer fluctuations and indications that were clearly incorrect compared to our visual descent profile while on runway centerline; and this continued up to threshold crossing. We brought this to the attention of andersen tower after landing and they stated that they sometimes receive reports that the ILS is unreliable due to weather conditions.
Original NASA ASRS Text
Title: Boeing 737 Captain reported erratic ILS course and glideslope indications while proceeding inbound in visual conditions.
Narrative: When cleared for the ILS-6R into UAM; the autopilot was used to intercept the final approach course while descending to our assigned altitude of 2700 feet MSL to intercept the glideslope. Shortly after localizer capture; the autopilot turned itself off and we noted some erratic ILS course and glideslope indications while proceeding inbound in visual conditions. While we were in the process of recognizing these incorrect ILS indications; the aircraft deviated slightly from the final approach course somewhere in the vicinity of the final approach fix. We corrected this deviation once we noticed it; but did [not] receive any glideslope indications until 600 feet AGL. We continued to receive localizer fluctuations and indications that were clearly incorrect compared to our visual descent profile while on runway centerline; and this continued up to threshold crossing. We brought this to the attention of Andersen Tower after landing and they stated that they sometimes receive reports that the ILS is unreliable due to weather conditions.
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.