Cardiff ILS

[wingit 0]

Not sure if this is the right place for this but can someone tell me why when using ILS into Cardiff you end up slightly to the right?

[mutley 4,497]

Hi wingit, I'll move it to Flight Sim General

Cheers

[rob16584 42]

It may be an offset ILS, in which case you will need to hand fly the last few hundred feet.

Which a/c are you using? If you don't have the course bug set correctly the AP will follow the course you set

[allardjd 1,853]

It may be that the localizer is deliberately offset from the extended runway centerline for terrain/obstacle clearance. It's not all that uncommon but is usually only a matter of a few degrees. It still brings you to the threshold, but at an angle, usually just a slight one. There is a special name that applies to the extreme cases as Rob refers to, but it escapes me at the moment.

 

John

 

EDIT:

 

http://www.airliners.net/aviation-forum ... ain/58517/

 

The term I couldn't think of is LDA (Localizer-type Directional Aid). According to this thread there are quite a number of them, but no mention of Cardiff. What's the ICAO code?

 

JDA

 

EDIT EDIT:

 

From Wiki:

 

"Localizer Type Directional Aid is of a comparable accuracy and use to the Localizer, except that LDA is not aligned with the runway. An LDA Approach uses a localizer of normal width, which is 5 degrees wide, that can come into the runway at an angle, or can be offset. It may have marker beacons and a glide slope, just as other precision approaches have, such as ILS Approaches. If the alignment is not greater than 30 degrees, straight-in approach minima may be published. Circling minima only are published when alignment exceeds 30 degrees.

 

JDA

[rob16584 42]

EGFF is the ICAO John.

If you are coming in on rwy12 then it could be to avoid St Athan airfield which is pretty close to EGFF, it wouldn't make sense to offset on rwy30 as that is from over the water.

Do you have any payware scenery installed? It may be a big with that

[allardjd 1,853]

I'm finding no offset in the documented approach. The localizer is 121 degrees magnetic. The runway heading is just a hair shy of 117 true. The magnetic variation is -4. Those are RW values. What I see examing the FS9 airport and navaid properties matches up pretty closely with those values.

 

On final, if in VMC, the eye can really see very slight offsets from the RW centerline. Remember you have a strip of pavement about a mile or more long as a visual reference, so a small offset from that is going to be quite obvious. If I remember right, 1 degree at 1 mile is about 100 feet. If you're 100 feet off the centerline at a mile, it's going to look to you like you're in the next county, even though it's only one degree.

 

If you leave the AP connected in APP mode and just keep hands off, is there a lateral offset from the centerline when you get to the threshold? (I know - you're supposed to disengage the AP long before that, but it's just a test.)

 

I'm guessing this is OK. The published RW docs do indicate St. Athan lies close to the approach path, but there's no apparent offset in the official publications for the approach.

 

John