Intercepting GS/ Prior to LOC on ILS Approaches.

Tom Campagnola

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Intercepting GS/ Prior to LOC on ILS Approaches.
« on: November 12, 2018, 10:56:56 am »
Hello All,

Many times we are vectored in close to the Final Approach fix to help traffic flow to an airport, and in doing so, fly above the GS. Last night while vectored to the Final of 24R CYYZ, I was vectored into the ILS LOC and when i realized i was high on the approach, 'i asked if i could descend below the 3000' alt, due to the fact, I was high on the GS and the LOC had not centered". The Controller stated i was cleared for approach, and i could descend. I remarked, i like to be on the LOC prior to descending down the GS, specially if the MSA is just about the same Altitude as the GS intercept Alt.

I wasn't cleared for a Visual Approach and wasnt issued the typical.....maintain 3000' till established on the LOC. I was just issue a turn to 340 deg intercept the LOC, cleared for approach 24R....So, I dont really know the procedure.....

My experience back in the Big BLue Ball days was not to start descent on the GS until established on the LOC. In the B727 Days, the auto pilot would not be able to capture the GS from above, they had the GS MAN, which would dive down, remember, we arent supposed to push the airplane over and have the passengers drinks disturbed.

Anyway, Did I do the right thing? I am not for the deep dive to GS capture guy and would certainly be ok to be vectored outside the marker and told Keep My SPEED up...

I tried looking for FARs on this or AC's but no joy


Evan Reiter

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Re: Intercepting GS/ Prior to LOC on ILS Approaches.
« Reply #1 on: November 12, 2018, 12:01:01 pm »
In Canada, there is no requirement to issue an altitude to maintain the way we do in the United States. Quite frequently, an ILS clearance will be "turn left heading 270, cleared ILS Runway 24R Approach".

In Toronto, there are local noise abatement procedures that are conveniently buried in the CFS (or the Jeppesen Reference pages) that state you must maintain 3,000' ASL until established on the localizer, and fly all approaches, including visual, on the localizer and glideslope.

You're correct in saying that you should not start descending on the glideslope until establishment on the localizer, as the glideslope isn't relevant to you until you're tracking the localizer as well. In your case, the options are either to wait until you join the localizer, then start a rapid descent (say, using VS or Flight Level Change) to re-capture the glideslope, or just ask to be vectored further from the airport, depending on the situation.

Nickolas Christopher

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Re: Intercepting GS/ Prior to LOC on ILS Approaches.
« Reply #2 on: November 12, 2018, 07:13:51 pm »
I wonder if you vectored far enough away from the GS intercept point so that you could descend appropriately. Controllers should not vector you above the glideslope. You should be able to intercept the localizer and be established prior to descent.
ZLA Air Traffic Manager

Raymond Salvagnini

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Re: Intercepting GS/ Prior to LOC on ILS Approaches.
« Reply #3 on: November 15, 2018, 02:30:21 am »
If anyone is interested in the reference it’s AIM 5-4-6

“1. Maintain the last altitude assigned by ATC until the aircraft is established on a published segment of a transition route, or approach procedure segment, or other published route, for which a lower altitude is published on the chart. If already on an established route, or approach or arrival segment, you may descend to whatever minimum altitude is listed for that route or segment.

2. Continue on the vector heading until intercepting the next published ground track applicable to the approach clearance.

3. Once reaching the final approach fix via the published segments, the pilot may continue on approach to a landing.”

In this case established on a published portion of the approach would be on the LOC. However, there is some debate on when you’re established on the LOC, is it when the LOC starts moving or when it’s completely centered? I’ve always been told that when the LOC starts moving you can start descending, but I haven’t found a reference for that.
Raymond Salvagnini
Air Traffic Manager
Virtual Washington ARTCC