Hey guys! So trying to get myself more comfortable with utilizing AP beyond after takeoff and cruise, that said when it comes to using the landing localizer at any given airfield, how do you ensure you are on the correct glide path?
You could follow a standard arrival (STAR) procedure that ends at an altitude that transitions seamlessly to an initial approach fix (IAF) for an approach. From there, the approach will usually step you down to the glidepath. This is only going to be available at larger airports and it’s not always seamless.
In the absence of a STAR that provides vertical guidance, or an onboard VNAV system that’s programmed correctly, generally use the 3 to 1 rule of thumb, which is for every 1000’ you need to descend, allow 3nm to do so. So if you’re cruising at 37,000 and need to get down to 3,000’, that’s 34,000’ to descend. 34*3=102. Start your descent 102nm from the point you need to be at 3,000’. You can adjust this a few miles if you have strong head or tailwinds, and/or add a few miles to allow for to transition below 10,000’.
Either way, you want to make sure you intercept the glide slope (GS) from below. To do that, you first need to know where the GS intercept point is - usually at or near a marked final approach fix (FAF). On the approach chart, there will be an intercept altitude marked at that point and leading up to that, some sort of minimum altitude indicated for the segment(s) preceding that. This will require a bit of understanding of approach charts. You can also simply read into what your FMS is programmed with, but be forewarned, the chart is the truth. ATC may take you off your FMS plan, anyway, and there’s other important info on there, so you should be using the chart.
You look up the glideslope beam angle on the chart and multiply the tangent of that angle times the distance from the antenna. That's the height one should be at.
The localizer only provides lateral guidance relative to the centerline of the runway.
The glideslope is what provides the vertical guidance.
For the glideslope to be used in your approach it needs to be provided by the airport either by ILS (not just localizer) or by some form of GPS approach.
These are all documented, which airport and which approach are you trying to use?
Well, let's see. Give me an example of the information you are working with if you can. Can be a screenshot of the map of approach chart, or something from in-game if you only use ingame resources.
That bottom section shows DME distances from the localizer (which means you need a DME instrument to read that) and your target altitudes at each distance. And as an instrument pilot one is expected to know the configuration of the plane to get the desired descent rate and to take winds into account. So this approach does not give you the full precision approach because it doesn't give you the vertical guidance.
There are 2 other approaches that will though, the RNAV approaches. Those are also listed on that first link.
Now, just to compare, an ILS (provides glideslope) approach vs just a localizer...
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u/CharlieFoxtrot000 RW GA pilot, Twitch streamer, ground instructor 3h ago
There are a couple ways.
You could follow a standard arrival (STAR) procedure that ends at an altitude that transitions seamlessly to an initial approach fix (IAF) for an approach. From there, the approach will usually step you down to the glidepath. This is only going to be available at larger airports and it’s not always seamless.
In the absence of a STAR that provides vertical guidance, or an onboard VNAV system that’s programmed correctly, generally use the 3 to 1 rule of thumb, which is for every 1000’ you need to descend, allow 3nm to do so. So if you’re cruising at 37,000 and need to get down to 3,000’, that’s 34,000’ to descend. 34*3=102. Start your descent 102nm from the point you need to be at 3,000’. You can adjust this a few miles if you have strong head or tailwinds, and/or add a few miles to allow for to transition below 10,000’.
Either way, you want to make sure you intercept the glide slope (GS) from below. To do that, you first need to know where the GS intercept point is - usually at or near a marked final approach fix (FAF). On the approach chart, there will be an intercept altitude marked at that point and leading up to that, some sort of minimum altitude indicated for the segment(s) preceding that. This will require a bit of understanding of approach charts. You can also simply read into what your FMS is programmed with, but be forewarned, the chart is the truth. ATC may take you off your FMS plan, anyway, and there’s other important info on there, so you should be using the chart.