ILS mis-alignment

[nrcapes 0]

No matter which airport or which ILS approach, or which aircraft, with autopilot and approach hold on, the localizer is mis-aligned with the runway, so I have to do a slight left bank right before landing. I have not added any scenery or changed any airport files. I have the latest Navigraph loaded into FS Commander and Radar Contact.

 

Any clue?

[pegger74 18]

Change of magnetic variation over time? That would be my guess. FSX is several years old now, so if you are running the course illustrated on the latest charts, you could be a degree or two off from the 6 year old FSX alignments. Try flying the approach using the default runway data in FSX. and see if it makes a difference.

[N60JBravo 27]

so I have to do a slight left bank right before landing.

Congratulations, you're now a pilot.

 

Change of magnetic variation over time?

How can that cause this issue?

 

Runways, and their ILS localizers, are set to a true heading and that does not change.

 

regards,

Joe

[mosteen 111]

The very useful MagVar corrections are here to be found

 

http://www.aero.sors.fr/navaids.html

[mgh 89]

 

 

Runways, and their ILS localizers, are set to a true heading and that does not change.

 

But they are designated by their magnetic heading. That is why runways are renumbered from time to time as the magnetic declination changes. Also, bearings shown on approach charts are magnetic not true.

 

FSX runways and ILS are  based on the magnetic declination when it was developed several years ago. Using up-to-date information will result in discrepancies.

[scott967 63]

But they are designated by their magnetic heading. That is why runways are renumbered from time to time as the magnetic declination changes. Also, bearings shown on approach charts are magnetic not true.

 

FSX runways and ILS are  based on the magnetic declination when it was developed several years ago. Using up-to-date information will result in discrepancies.

 

OK but if you are centered on the localizer you are centered on the localizer.  Assuming the localizer is aligned to runway centerline (true in most instances) then if you keep the localizer centered you are flying the along the runway centerline ground track.  Of course, your actual heading will vary based on winds and the like.

 

scott s.

.

[OmniAtlas 93]

Look at the flaps2approach web site. This issue was covered thoroughly.

[pegger74 18]

Runways, and their ILS localizers, are set to a true heading and that does not change.

Well thanks for your help on this one... :unsure: . You might want to look that up for future reference.

OK but if you are centered on the localizer you are centered on the localizer

Yep. and a localizer is just like a VOR..you are flying a radial into the localizer. And VOR radials are magnetic. so are the localizer courses as published.

[nrcapes 0]

Congratulations, you're now a pilot.

 

How can that cause this issue?

 

Runways, and their ILS localizers, are set to a true heading and that does not change.

 

regards,

Joe

 

Actually I am a real-world instrument pilot, but FSX is not real-world!

[N60JBravo 27]

nrcapes, on 15 May 2013 - 4:56 PM, said:

Actually I am a real-world instrument pilot, but FSX is not real-world!

As a real-world instrument pilot I would think you would know that many ILS localizers are not aligned with the runway.

 

And thanks for telling me that FSX is not RW. I never knew that.[/sarcasm]

 

regards,

Joe

[nrcapes 0]

Look at the flaps2approach web site. This issue was covered thoroughly.

Where on the site?

[N60JBravo 27]

Well thanks for your help on this one... :unsure: . You might want to look that up for future reference.

Are you saying that I am wrong?

 

Are you saying that runways and localizers move with changes in magnetic declination? 

 

 

Yep. and a localizer is just like a VOR..you are flying a radial into the localizer. And VOR radials are magnetic. so are the localizer courses as published.

Actually VORs and localizers are nothing alike, other than they are both navaids.

 

Localizers don't have radials.

 

VOR radials are aligned magnetically, from time to time. They do not automatically adjust to changes in magnetic declination. As time goes by they wander away from being in alignment with the compass and have to be tuned.

 

None of this really matters because we don't fly instrument procedures with the compass.

 

regards,

Joe

[JRBarrett 3,273]

Yep. and a localizer is just like a VOR..you are flying a radial into the localizer. And VOR radials are magnetic. so are the localizer courses as published.

Actually, localizers are NOT like VORs. They operate in the same frequency band (108 to 117.9 MHz), and use the same radio receiver and display instrument in the cockpit, but their operating principles are quite different.

 

A localizer "knows" nothing about magnetic or true headings, and the transmitted signal is not a "radial" The course deviation indicator (CDI) needle position is solely dependent on the aircraft's physical position in relation to the center of the transmitted beam from the localizer antenna array on the ground. Most localizers are physically aligned with the centerline of the runway, but in some cases, the beam centerline may be offset (for a variety of reasons).

 

Unlike the case when navigating to or from a VOR, it does not matter what the course selector on the nav instrument is set to... The CDI needle will center when the aircraft is physically positioned in the center of the transmitted localizer beam, no matter what the selected course. Not setting the proper course would be poor practice though, especially when using an HSI, as the instrument would give the pilot an inaccurate representation of the aircraft's relative position in relation to the runway - but even so, the needle would still center when the aircraft flew through the centerline of the localizer.

[OmniAtlas 93]

Where on the site?

A simple google search yielded these results.

 

http://www.flaps2approach.com/journal/2013/1/16/magnetic-declination-fs9-fsx-navigation-datebase-update.html

[nrcapes 0]

As a real-world instrument pilot I would think you would know that many ILS localizers are not aligned with the runway.

 

And thanks for telling me that FSX is not RW. I never knew that.[/sarcasm]

 

regards,

Joe

I'm not going to get into a flame on this, but you are incorrect about an ILS not being aligned with a runway. See the AIM. You may be thinking of an LDA. In any case, obviously FSX does not have a localizer receiver, so I assume it relies on the position of the aircraft in relation to the simulated ILS.

 

1−1−9. Instrument Landing System (ILS)

 

a. General

 

1. The ILS is designed to provide an approach path for exact alignment and descent of an aircraft on final approach to a runway.

 

Localizer Type Directional Aid (LDA)

 

1. The LDA is of comparable use and accuracy to a localizer but is not part of a complete ILS. The LDA course usually provides a more precise approach course than the similar Simplified Directional Facility (SDF) installation, which may have a course width of 6 or 12 degrees.

 

2. The LDA is not aligned with the runway.