JT! We lost something when some airports took away the approach NDB which enabled a 'confidence check' on the correct localiser position. Now we have LNAV and MAP which are fine as long as they mean what they say! Too many people rely on the MAP display for SA.
Perhaps BM could amplify his question a little so we can see what he is getting at? For example, if one were flying a visual approach using ILS as a 'monitor', it would be 'NORMAL' and safe to start using the GP as a further clue to profile before being on the localiser, and indeed to be desending below published GP 'capture altitude', as one would on base for a visual circuit.
As John says, though, IFR - with EXTREME caution (best to let ATC help you!), and with JT's 'lumpy bits' around...........oooohhh! I recall Brussels had a 'false localiser capure' NOTAM for R25 for years - it may still have?
PS Not too many 'lumpy bits' there
