The localizer demarcates the center line of the runway, and is used to indicate horizontal deviation on the CDI at the bottom-middle of the HUD.
It is not the red cone. The red cone is a visual aid put on the map and mini-map in IF. Nothing more.
When told to maintain 180 until established on the localizer, say, for runway 15, this means that as the CDI nears the middle line [slight clarification: in my mind I was thinking “when the line stops blinking and begins moving toward the center”, not as @MJames pointed out, just before it hits the center, that would be too late], you should turn to runway heading so that you are aligned with the center line.
It does not mean you continue to fly 180 until you hit the cone. The cone, again, is a visual aid, not part of the Instrument Approach.
'Til established on the localizerrr, yeah, yeah, yeahhhh
You gotta fly, you gotta turn, you gotta line 'er up
Ain’t no pilot got time for a rest
Run, run, run for the slammer
'Cause the controller will hit ya with a hammer
Mic drop.
I thought this would be a useful rhyme for those who are musically inclined. Excellent reminder as usual, Tim. This is why you’re my spirit guide.
CDI is Course Deviation Indicator. For the localizer, are you to the left of the center line, to the right, or on it. Found in the center of the bottom part of the HUD. For vertical deviation from the glidescope, use the arrow on the right.
The red ILS cone being the visual aid placed on the map. It doesn’t actually exist. It’s just there for assistance.
What happens, is in IF, pilots think that the cone is the same as the localizer, so if you put them on an intercept course where they will intercept the localizer further out than the cone (pretty much necessary at KASE, they will fly that intercept heading until they hit the cone on the map…except they never will, because that wasn’t the point. They just keep going and going past the center line.
Also to clarify, you are ‘established’ once the lateral needle starts to move. You don’t need to wait until it’s ‘near’ the center or on the center (or in the red cone as this post correctly stated). Once the needle is moving, you ARE established and can now descend past the altitude given to maintain by ATC, or turn etc as needed.