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Outer markers, MM, and IMs.. do they exist?
Hi Everyone,
Currently working on my IPC and studying the good ol theory and came across theory on outer, middle and inner markers. I first learned of this around 14 years ago and it's cropped up again in my OLD theory notes. Does anyone know of an ILS in Aus that still uses them? The ILSs I'm familiar with don't use them. Thanks everyone! *sorry if this is posted in the wrong section All the best. |
Cairns 15 has a MM
Not sure if there were ever IM in Australia |
If my decaying brain is correct, the outer marker beeped "N" in Morse and the middle beeped "A". Never heard an inner marker except in a sim.
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Originally Posted by belongamick
(Post 11363029)
Cairns 15 has a MM
Not sure if there were ever IM in Australia ... Some overseas installations utilise a third marker beacon (inner marker) which is modulated at 3000-hertz, identified by a keyed continuous signal of six dots per second and is located 75–450 metres from the runway threshold. There are no inner markers associated with ILS installations in Australia. |
Yeah I thought so. They were usually associated with CAT II and CAT III ops of which we basically didn't have any at the time.
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Originally Posted by JamieMaree
(Post 11363123)
That is rubbish. There were OM and MM associated with good old 300’ minima ILSs. They were there to check that you were on the correct lobe of the glide slope. ( that is confirmed by the text in the old DCA document)
I can still remember that the OM height for the SY 16 ILS was 1310’. A standard call was : “ Outer Marker, height checked” IIRC the outer locator was WPB, the inner locator was SDM, the OM was around the Gladesville bridge and the MM was around SDM. |
Amberley still has them, one other joint that I know of has them, can't recall at the mo.
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The original question by the OP was.... Outer markers, MM, and IMs.. do they exist?
The majority of ILS installations now come with a co-located DME, so the need for markers has diminished. |
Oakey has a MM parked in the paddock next door. Lobes corrected for passing sheep.
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Lobes corrected for passing sheep |
With ILS DME and GPS the markers are pretty much redundant. But as some have alluded to there are a couple still around. Inner markers (white) were associated with low viz CAT2 and 3 and Australia never had any at the time.
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