ILS - incorrect angle?

#1

I’ve done a fair amount of searching here and watched tutorials online. This is the situation which I had today:

  1. Made an ILS approach to LFPG (Paris Charles de Gaulle)
  2. Angle of Approach was ca 260 degrees.
  3. I flew this and matched the glide slope
  4. However, I ended up about 1 mile north of my target runway, absolutely parallel. The localiser line was to the left of the centre line but had I chased it I would have gone far off the ILS angle of approach.

I’m sure I’m making a rookie error here so any advice would be most welcome. Thanks.

PS if a moderator thinks this is a repetitive post please do close once I’m redirected. Thanks!

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#2

Which runway at LFPG were you inbound on?

#3

Not sure I quite understand you on this, but I have not had any problems at LFPG before. Was there a crosswind that you were not compensating for perhaps? If the runway direction is 260 but there’s a crosswind then you may find that you need to be ‘heading’ as much as 5 degrees either side of that in order to actually be flying 260 and lining up for the runway.

#4

I know you mentioned you said you looked through some of the tutorials but this one is extremely helpful for those ILS/GPS approaches. I know that this topic that I have linked below is for the APPR mode, and not all aircraft we have include the APPR mode, but its still helpful to utilize some of these techniques when establishing yourself on the approach.

The key point that you might want to make note of is this bullet:


If the approach is not locked, its possible that you can be flying the approach for a near by airport which may be beyond the intended airport of landing.

By selecting the approach and locking the approach, you are able to guarantee that you are flying the correct approach for the specific runway at your intended airport.


If all else fails and you find that the above steps as outlined in the tutorial is still taking you off course, let me know and I can look further into it. Thanks and let me know how things turn out!

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#5

26R - flew in from the East (having crossed the Channel)

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#6

Thanks a lot will check that out as well

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#7

I’ve just checked out 26R at LFPG, it looks like the runway heading is actually 270 not 260 as there are four parallel runways so they have two different numbers. Try again using a heading of 270 not 260 and you should land perfectly on 26R.

Try that and read and try all Deer has said and between the two you should be able to land perfectly!

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#8

That must explain it! Knew there was a Level 1 Rookie Error going on here somewhere. Thanks a lot to everyone.

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#9

All good. Next time just maually fly it down yourself. 😂

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#10

Check the chart below. Below are where on most standard charts you will find the heading of the runway.

image

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#11

👀 This has happened to me too !!👀

#12

I have never followed a localizer in IF and ended up with horizontal deviation [KSFO 28R even has the wrong heading, but the CDI still work properly]. (You say you followed the glidescope, but this won’t help you with North and south, since the glidescope is vertical, not horizontal.)

If you follow the localizer, and keep the CDI centered, you should be fine. The issue is that not many runways are exactly whole number headings. Very often you will find that 265° is actually 265.4° or something. It seems small, but it will make a difference over the long term if you try to fly the entire final leg with HDG set on AP. And obvoously, wind is a factor most of the time. There will almost always be a point at which you’ll need to make manual adjustments, but that’s not an issue so much as the realities of physics.

#13

Thanks. I guess the noob question I have is whether I should be following the hdg of the ILS approach or the vertical line that sits on the compass. Often, until the last moments, the heading and the vertical localiser line do not line up. Am I missing a trick between when the localiser is flashing and when it becomes solid?

#14

I guess you can kind of look at it on the macro- [big-picture] and micro- [more detailed] level.

Macro, the heading of the ILS will give you a good starting point, for example, the westbound runways at KLAX are 250°, so you know your heading will be around there.

However, if you start 10 miles away and set your heading to 250, the chances of you landing on the centerline without any correction are virtually nil.

So, as you get closer to the threshold, making sure that centerline deviation indicator (CDI) stays directly in the middle, and to do that, you’ll have to make small manual corrections. The closer you get, the more small changes will affect the indicator. Minor adjustments are less important 10 miles out than the last mile, for example.

But you definitely need to keep that CDI in the middle, and AP (without APPR) will very rarely accomplish that. Now, you can still use AP along the way, but you’ll need to make manual adjustments at some point, and it becomes more important the closer you get.

When the CDI is flashing, it just means that you are farther afield of the centerline than the threshold for the indicator. So, if it’s flashing on the far left, you need to make quite a large swing over to your left to catch the localizer. When the CDI stops flashing, you’re getting closer to catching the localizer, so you know that you are getting close® to the centerline. When the CDI is in the exact middle, you’re on the centerline. Anywhere else, and you’re either left or right of the center line. If you’re on final and the CDI goes from solid to flashing, you’re in trouble, as you’ve deviated quite a ways from the center line.

What generally should happen is that, say you’re on approach and given a 30 degree intercept, it will start flashing, then become solid and start moving toward the center, when this happens you’ll want to turn to that heading that you’ve been trying to use, and timing it such that you hit that heading right when the CDI is directly in the middle. That’s intercepting the localizer.

That will get you close, as stated before, but manual adjustments should be made along the way to keep that CDI in the middle the whole way.

10 miles out, if you still want to use AP as much as you can as you learn to control other things, you can make one-degree adjustments to AP heading to get the line back in the middle. But the last few miles, you’ll definitely have to go manual at some point, with maybe some rare exceptions where everything is just right, to make sure that you touch down on the centerline.

It just takes practice like anything else.

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#15

Man this is a guide to memorise. Thanks a lot. A lot to absorb and learn here.

#16

Also keep flashing your eyes to the wind indicator, as things can (and often do) change the lower you get and your required offset from the runway heading may need to be continually adjusted to keep yourself on target.

I just did a particularly problematic approach into YPPH, where a crosswind reversed in the last couple of miles down to the runway. After a poor approach to begin with (seriously need to not get distracted when I’ve started my descent), the final was hard work and I’m fairly sure I landed way off the centreline. I then went for the hat-trick by failing to use proper ground procedures and exited the runway too soon, thus getting in to conflict with aircraft heading from the ramp to the runway hold. All in all, it was not my finest hour on IF.

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closed #17

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