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If you use your two ADF's in the aircraft for the Twin Locator approach (regardless of the Australian AIP which now talks about a NDB rather than Twin Locator approach), then the closer you get to the runway (let us say in the case of Avalon, Victoria), the less accurate will be the bearing of the first locator you pass over, simply because of distance errors. On the other hand as you close in on the second locator, which is situated in the case of Avalon, only 0.57nm from the threshold, logically it is the more accurate.
So what is the point of having one ADF needle on a navaid that is getting progressively less accurate, when in practice it is the tracking on the one closest to the runway which interests you more. The only use of the first locator (8.1 nm from threshold) in the case of Avalon is for top of descent geographical postion. After all - you have to start down somewhere especially where in the case of Avalon the DME is not part of the procedure.
Once you have passed that point and descent is started, it is probably better to bring up both aircraft ADF's to the remaining locator for increasingly accurate track keeping and for redundancy in case one ADF should pack up (very unlikely unless you are having a bad day).
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