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Old 4th Jul 2018, 19:36
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Crazy Voyager
 
Join Date: Sep 2010
Location: Home away from home
Posts: 562
Council van has answered it pretty well.

The exact point where the approach is intercepted mainly depends on traffic, if there is not traffic aircraft are vectored for as short of an approach as is possible while still complying with things like terrain and providing enough track miles for a stable approach. Normally if there is no traffic in the way aircraft tend to intercept the ILS between 7 and 10NM.

If there is traffic ahead final approach often starts to move out, this is simply because it is one of the ways spacing is adjusted. Aircraft are roughly spaced the correct distance on the downwind but the further out the less precise the spacing is. As the pattern then gets closer to final it is adjusted. If there are more aircraft the approach intercept tends to move out to around 10-12NM, if it's really busy or a late increase in spacing is needed it can increase even more, but rarely outside of 15NM unless doing straight in approaches (which can see aircraft join final approach a long way out, on 05 somertimes almost 40NM out).

To throw a spanner in the works some aircraft ask for shorter approaches or opt for visual approaches, on 05 a visual approach can establish at any range (no noise restrictions on 05 ops for visuals). Also sometimes airlines fly non-precision approaches for training, ryanair quite often fly loc/dme approaches for crew training, they then tend to request 12NM finals to allow themselves time to set up before descending on the procedure.



Also to add a bit more, you talk about what sounds like the positioning of the downwind on 05. This is also depending on traffic. At busier times the downwind is kept further out from final to allow more room for final director to adjust the spacing. At quieter times the downwind leg is put tigher to final approach to reduce track miles and provide a more expeditious approach. Also some times traffic from the south routes via the hold fix at DAYNE (over towards Maccelsfield) and sometimes they can join on a heading from further south (at night even going down the "wrong" side of the airway at times and go over Birmingham) which again may make a difference to what passes over your house in what direction.

As Council Van says, have a look at flightradar 24 and look at some of the Manchester inbounds, you will see at busy times (say 8-9 in the morning for example, or around lunch time 1pm) they will route in a more square pattern and often route via the holding fixes. At quieter times the routes become more fluid with aircraft flying much more direct paths. Also compare some of the inbounds that come up over Wales when 05 is in use, some will fly all the way to the hold fix at MIRSI which is north of liverpool, some will join straight to final approach and most will do a bit of a dog leg to the north and then back again, but not go all the way to the hold.
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