Narrative:

[We were] being vectored for the ILS runway 07R approach at anchorage; ak. Visual meteorological conditions were present at the time.flight was controlled using the center autopilot. Airplane mechanical deferred items included the left autopilot as inoperative.at about ten (10) miles west of the airport and intercepting the localizer to runway 07R; the plane captured the course and continued. However; the localizer course failed to lock. The plane drifted off course and required correcting using the heading select commands. Small corrections were made and the localizer approach was re-armed. A few moments later the localizer was captured. The flight management annunciators displayed localizer; thus affirming course capture.the approach continued to the final segment; located about five miles from the runway. However; there was a second correction that was required. The autopilot was disconnected at about 1.6 miles and 500 feet AGL; the approach continued to an uneventful landing.this is the second occurrence in the past month of an irregularity with the ILS localizer runway 07R at anchorage. The localizer fails to lock after course capture.an aside; a conversation was made with another air carrier operator. They affirmed a question about the localizer locking course during approach to runway 07R.[suggest] careful monitoring of flight management annunciators during an ILS runway 07R approach at anchorage is standard operating procedure. An approach into instrument meteorological conditions and localizer lock failure would require prompt intervention; including considering a manually flown approach.

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Original NASA ASRS Text

Title: B747 First Officer reported a course deviation resulted when the ANC 07R localizer signal displayed anomalies. Reporter stated he has seen this issue in the past.

Narrative: [We were] being vectored for the ILS runway 07R approach at Anchorage; AK. Visual Meteorological Conditions were present at the time.Flight was controlled using the Center Autopilot. Airplane mechanical deferred items included the Left Autopilot as inoperative.At about ten (10) miles west of the airport and intercepting the localizer to runway 07R; the plane captured the course and continued. However; the localizer course failed to lock. The plane drifted off course and required correcting using the Heading Select commands. Small corrections were made and the localizer approach was re-armed. A few moments later the localizer was captured. The Flight Management Annunciators displayed LOC; thus affirming course capture.The approach continued to the final segment; located about five miles from the runway. However; there was a second correction that was required. The autopilot was disconnected at about 1.6 miles and 500 feet AGL; the approach continued to an uneventful landing.This is the second occurrence in the past month of an irregularity with the ILS localizer runway 07R at Anchorage. The localizer fails to lock after course capture.An aside; a conversation was made with another air carrier operator. They affirmed a question about the localizer locking course during approach to runway 07R.[Suggest] careful monitoring of Flight Management Annunciators during an ILS runway 07R approach at Anchorage is standard operating procedure. An approach into instrument meteorological conditions and localizer lock failure would require prompt intervention; including considering a manually flown 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.