A B737 pilot flying a sea runway 16R visual approach in the ILS app mode noted a track deviation and...

Narrative:

On approach to runway 16R in seattle in scattered cloud conditions while visually following preceding traffic to the runway I armed the ILS approach mode as a backup to the briefed visual approach. All ILS approach and arrival briefings were accomplished. ATIS was advertising approaches to 16L and 16R and departing 16L. We were told to maintain 3;200 until bugne then cleared 16R. I noticed the aircraft cross slightly to the left of the 16R centerline so I disconnected the autopilot and corrected back to the 16R centerline. The identifier for the ILS showed 34L so we continued the visual approach to uneventful landing. After blocking in at gate we called ground control to inform them that the 34L localizer was active. I called tower and TRACON on the telephone to inform them of the issue also. The TRACON supervisor told me the localizer was supposed to be down for maintenance and that the 34L localizer should not have been operating.there were two primary issues. First; the localizer was active for the opposite direction runway when it should have been off. Second; I armed the approach as a backup while not visually assuring the identification. The deviation was identified and only a minor deviation occurred.

Original NASA ASRS Text

Title: A B737 pilot flying a SEA Runway 16R visual approach in the ILS APP Mode noted a track deviation and while manually flying back to centerline noticed the Runway 34L ILS identifier was active. ATC reported the 34L ILS was supposed to be off line.

Narrative: On approach to Runway 16R in Seattle in scattered cloud conditions while visually following preceding traffic to the runway I armed the ILS approach mode as a backup to the briefed visual approach. All ILS approach and arrival briefings were accomplished. ATIS was advertising approaches to 16L and 16R and departing 16L. We were told to maintain 3;200 until BUGNE then cleared 16R. I noticed the aircraft cross slightly to the left of the 16R centerline so I disconnected the autopilot and corrected back to the 16R centerline. The identifier for the ILS showed 34L so we continued the visual approach to uneventful landing. After blocking in at gate we called ground control to inform them that the 34L localizer was active. I called Tower and TRACON on the telephone to inform them of the issue also. The TRACON Supervisor told me the localizer was supposed to be down for maintenance and that the 34L localizer should not have been operating.There were two primary issues. First; the localizer was active for the opposite direction runway when it should have been off. Second; I armed the approach as a backup while not visually assuring the identification. The deviation was identified and only a minor deviation occurred.

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	1321125
Time
Date	201512
Local Time Of Day	0001-0600
Place
Locale Reference	SEA.Airport
State Reference	WA
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	B737 Next Generation Undifferentiated
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	Visual Approach
Flight Plan	IFR
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	ATC Issue All Types Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

A B737 pilot flying a sea runway 16R visual approach in the ILS app mode noted a track deviation and while manually flying back to centerline noticed the runway 34L ILS identifier was active. ATC reported the 34L ILS was supposed to be off line.