Narrative:

Descending through 10;000 ft; I pulled up the rad navigation page and discovered that all the data normally there was missing. About the same time ATC issued a turn and instructed us to intercept the localizer. I turned to the assigned heading and selected the localizer pb; and confirmed localizer on the FMA. I also noticed that the lateral displacement from the localizer course was approximately 6 miles. Just about the time I realized that the aircraft had not intercepted the localizer course; ATC indicated we had gone through the localizer and he issued a turn to re-intercept the localizer. We indicated we had the airport in sight and were subsequently cleared for the visual approach. As far as we could tell; there was no conflict with any other traffic and ATC made no indication that there was any problems associated with this incident. Indications were that all systems were normal with the navigation system on the aircraft except for the lack of data on the rad navigation page. I discovered this fact when I selected rad navigation to hard tune the VOR. I was 'scratching my head' trying to figure out what was going on when I discovered that we had flown through the localizer course. This was an inadvertent error on my part and it illustrates how a simple problem can distract the crew from the task at hand. Having had this happen to me I would be aware of the situation if it were to occur again; but given the circumstances and the chain of events that occurred; I could envision other crews making the same inadvertent error as we did.

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Original NASA ASRS Text

Title: An A320 Captain reported flying through the localizer on the approach when he was momentarily distracted with an FMC problem.

Narrative: Descending through 10;000 ft; I pulled up the RAD NAV page and discovered that ALL the data normally there was missing. About the same time ATC issued a turn and instructed us to intercept the localizer. I turned to the assigned heading and selected the LOC PB; and confirmed LOC on the FMA. I also noticed that the lateral displacement from the localizer course was approximately 6 miles. Just about the time I realized that the aircraft had not intercepted the LOC course; ATC indicated we had gone through the localizer and he issued a turn to re-intercept the localizer. We indicated we had the airport in sight and were subsequently cleared for the visual approach. As far as we could tell; there was no conflict with any other traffic and ATC made no indication that there was any problems associated with this incident. Indications were that all systems were normal with the NAV system on the aircraft except for the lack of data on the RAD NAV page. I discovered this fact when I selected RAD NAV to hard tune the VOR. I was 'scratching my head' trying to figure out what was going on when I discovered that we had flown through the LOC course. This was an inadvertent error on my part and it illustrates how a simple problem can distract the crew from the task at hand. Having had this happen to me I would be aware of the situation if it were to occur again; but given the circumstances and the chain of events that occurred; I could envision other crews making the same inadvertent error as we did.

Data retrieved from NASA's ASRS site as of April 2012 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.