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What Do Localizer Antenas Look Like?  
User currently offlineFP_v2 From , joined Dec 1969, posts, RR:
Posted (15 years 1 month 6 days 2 hours ago) and read 3416 times:

Today while sitting near the threashold of the runway at my local airport I started wondering where the DME/Localizer antenas were. I always thought that the localizer antena is an assembly of wires spanning the width of the runway. All I could see behind me(with a fence around it)was a rather large box with red and white squars painted on it and a pole about 5-8 meters tall right beside it. Was that it?

8 replies: All unread, jump to last
User currently offlineBuff From Australia, joined Mar 2007, 0 posts, RR: 1
Reply 1, posted (15 years 1 month 5 days 16 hours ago) and read 3351 times:

The localizer transmitter is almost always at the departure end of the runway. It provides a much more stable signal to an aircraft all the way to the touchdown zone - theoretically. That's why backcourse approaches have higher minima and are harder to track "close in" because you are nearly overtop of the transmitter on short final.

An exception to this statement is the Track Guidance Localizer (or whatever it's called now!) which is not lined up with the runway centreline. It's purpose is to give precise track information to get the aircraft in close enough to execute a visual manoeuvre to finally land the aircraft, or to get it into the valley where it can intercept an ILS or other approach aid. These devices are usually found in mountainous areas.

Best Regards,


User currently offlinePilot1113 From United States of America, joined Aug 1999, 2333 posts, RR: 11
Reply 2, posted (15 years 1 month 5 days 1 hour ago) and read 3313 times:

That red and white shed you saw is the ILS.

The localizer actually looks like this (colored red):

= = =
| | |

- Neil Harrison

P.S. I tried with just text. I'll scour the 'net for some pics.

User currently offlineNOTAM-J From United States of America, joined Mar 2001, 85 posts, RR: 0
Reply 3, posted (15 years 1 month 4 days 23 hours ago) and read 3308 times:

Great question! I think many people know what an ILS, VOR and DME are but aren't sure what they actually look like.

Most of us know that a VOR station is that round building with the cone on top. The cone part of the VOR is actually the DME equipment.

There are several parts of an ILS, but the two that give you horizontal and vertical guidance are the Localizer and Glideslope antennas respectively. The Localizer looks like an array of antennas opposite the approach end of the runway. They look like this: http://www.airportSystem.com/14el_LocAntenna2.html

Click for large version
Click here for full size photo!

Photo © Michael Glick

As for the Glideslope antenna, it is the tall pole next to the white and red checkered building. It looks like this: http://www.airportSystem.com/BandGSAntenna2.html

Click for large version
Click here for full size photo!

Photo © Chris White

For an ILS there can also be up to three marker beacons along the approach and are further away from the airport. They provide the pilot verification as to how far away from the runway they are. They look like this: http://www.airportSystem.com/MarkerBeacon2.html

There are also several lighting configurations that go along with an ILS.

Click for large version
Click here for full size photo!

Photo © Miguel Snoep

Hope this helps answer your question, and stay curious.  Big grin

If only I had a nickel for every Boeing vs Airbus posting...
User currently offlineFP_v2 From , joined Dec 1969, posts, RR:
Reply 4, posted (15 years 1 month 4 days 7 hours ago) and read 3275 times:

So you guys are saying that the localizer was is at the oppisite side of the runway? Here in town we have a localizer/dme system on runway 26..........does this mean that the antena is acctually at the threashold of runway 08? Why?

User currently offlineJETPILOT From United States of America, joined May 1999, 3130 posts, RR: 27
Reply 5, posted (15 years 1 month 4 days 7 hours ago) and read 3274 times:

If the localizer wasnt on the other end of the runway then you would have a station passage,reverse sensing, and ambuguity when you passed the localizer. The sensitivity would be so high the instrument would be unreliable.


User currently offlineApuneger From Belgium, joined Sep 2000, 3036 posts, RR: 10
Reply 6, posted (15 years 1 month 3 days 21 hours ago) and read 3251 times:

Great topic. So, if I'm right, the localizer antenna and the glideslope antenna are located quite far away from each other?

| |
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| | GS (or on the left side)
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| Direction of ILS approach


PS: Damn, had to edit this post 10 times before it looked allright

Ivan Coninx - Brussels Aviation Photography
User currently offlineFlybulldog From United States of America, joined Aug 2000, 371 posts, RR: 0
Reply 7, posted (15 years 1 month 1 day 10 hours ago) and read 3216 times:

So what is the outer marker?

User currently offlinePilot1113 From United States of America, joined Aug 1999, 2333 posts, RR: 11
Reply 8, posted (15 years 4 weeks 1 day ago) and read 3174 times:

The Outer Marker is usually an NDB.

The OM is, in most cases, the initial approach fix for an instrument approach. This is where you'd start the time for a non precision approach, run down the checklist, and get situated for the approach.

- Neil Harrison

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