A few years ago, Airbus A300-B4 0400 ish. arrival at Dublin Rwy 28 Cat III, we intercepted the LOC at about 40 miles. Everything looked good until G/S capture about 9 miles.
V/L, G/S green, Land 3, etc. Aircraft then seemed to wander off the LOC by about 1 dot and did not correct itself. We left it to about 1500ft to see what happened and then decided to go around and have another go.
2nd approach from 9 miles was perfect.
So did the black boxes forget what they were doing having been on the LOC for so long? Maintenance said there were no faults.
Is this a problem with capturing the LOC from so far out?