BrodieBrazil From Canada, joined Nov 2003, 88 posts, RR: 0 Posted (9 years 4 months 1 week 1 day 15 hours ago) and read 2746 times:
Can somebody explain to me what the Localizer is all about. I hear a lot about intercepting it, but am not quite certain what how it helps on the approach.
I apologize in advance for such a basic question.
I say thanks in advance to anyone for helping me!
Saintsman From United Kingdom, joined Mar 2002, 2065 posts, RR: 2 Reply 1, posted (9 years 4 months 1 week 1 day 15 hours ago) and read 2740 times:
Very simply, its a system used for lining an aircraft up onto the runway heading (particularly useful if you can't see the runway. It uses a radio signal which when interprated by the aircraft, tells it to fly either left or right. This can be a visual indication or coupled to the autoplilot and flown automatically. Once the aircraft is established on the runway heading (no fly left or fly right signal) the aircraft flys towards the runway until it meets the glideslope, which gives the aircraft fly up or down signals, so that it can then come into land.
Jhooper From United States of America, joined Dec 2001, 6195 posts, RR: 13 Reply 2, posted (9 years 4 months 1 week 1 day 15 hours ago) and read 2729 times:
No problem; that's how we all learn, isn't it. Anyway, if you have a AIM handy, you can read about it. Also the FAA's "Instrument Flying Handbook" goes into detail on the subject.
Just a couple of points to add to the above, if you have a glideslope associated with the localizer, you have what's called an Instrument Landing System (ILS) approach, which is also a "precision" approach. A localizer only approach (non-precision approach) does not have glideslope guidance. Only certain runways at certain airports have localizer approaches. If you go to a local FBO and purchase the "U.S. Terminal Procedures" for your area, you can see what instrument approaches are available near you.
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BrodieBrazil From Canada, joined Nov 2003, 88 posts, RR: 0 Reply 3, posted (9 years 4 months 1 week 1 day 14 hours ago) and read 2720 times:
Thanks J...
One more question...
at what distance can the plane lock onto the localizer? then is it up to the pilot to intercept the glideslope, and when does that switch from heading to glideslope take place?
FredT From United Kingdom, joined Feb 2002, 2184 posts, RR: 26 Reply 4, posted (9 years 4 months 1 week 1 day 13 hours ago) and read 2716 times:
BB,
you intercept the localizer at a given altitude, the maintain that altitude until the glideslope "comes alive". Then, you remain on the localizer for left and right guidance while the glideslope tells you if you are high or low.
Both are essentially the same thing, just aligned at 90 degrees to each other. The localizer (LLZ) will tell you if you are left or right of the extended runway centreline* while the glideslope (GS) will tell you if you are above or below a nominal glideslope.
Cheers,
Fred
*There are localizers which are not aligned with the runway, offset localizers. There are even complete LLZ/GS combinations which lead you to an off-airport spot, intended to get you safely to a point where you can continue the approach using other means. In those cases, they are not considered ILS systems though.
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Jhooper From United States of America, joined Dec 2001, 6195 posts, RR: 13 Reply 5, posted (9 years 4 months 1 week 1 day 7 hours ago) and read 2701 times:
Also, the glideslope is much more sensitive than a localizer. If I remember correctly, the localizer is 4X more sensitive than a VOR (enroute navigation facility), and the glideslope is 14X more sensitive than a VOR.
Also, I think the localizer is reliable up to a distance of 18 miles and 30 degrees of centerline.
These facts are from memory. It's been 6 years since I got my instrument rating so somebody please correct me if this is incorrect.
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