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ILS capture query


tgon

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I don't quite understand the ILS capture point, that is, the distance the ILS beams extend to enable my aircraft to capture it. I use LittleNavmap for flight planning and airport data. For example, LittleNavmap reports PANC Runway 14R as Cat III, ILS & GS with a range of 27nm but I didn't capture the ILS until about 12nm. This happens at a lot of ILS airports with I fly into. For completeness, I also use RC4 for ATC and copilot but unsure if this has a bearing (sic).

 

So, how is FSX calculating the range when engaging APP will actually register an ILS intercept?

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I think it's all done by magic, personally;) I interpret the range of about 27 miles to mean that is when you start to hear the Morse code and the DME info shows up on the display. The ILS capture is usually between 12-16 miles out and the Glideslope is captured around 8-9 miles out.

Still thinking about a new flightsim only computer!  ✈️

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General explanation about default aircraft,of the glideslope and how to catch it.

This text just explains how to catch the glideslope in a default aircraft (like the b747_400 or 737_800 for example).

 

The glide slope has an angle of 3.3 degrees. This is also called 5% slope.

This is the relation between distance travelled vertically, and distance traveled horizintally. ( across a sloping track.

Explaining more would take too far.

 

However, there is a simple relationship between distanc vertical and distance horizontal on the glide slope.

"300ft down for every NM forward"

 

So, 10 NM from the touchdown zone, the glide slope is at 3000ft.

20 NM from the touchdown zone the glideslope is at 6000 feet.

 

I imagine a point 10NM from TDZ, at 3000ft where I want to end up. There I want to have the plane follow the glideslope down.

 

I usually come flying in at 3000ft above the ground.

20 NM from the RW I recieve the glideslope, at that distance the glideslope is above me.

getting closer I start to see the glideslope indicator moving down when I'm 14-13 NM from the TDZ.

That is the point I engage approach mode.

For a few seconds the plane keeps flying straight on.

Then, at exactly 10NM it intercepts the glideslope and starts to follow the signal down. Towards the TDZ.

 

I keep a close eye on alt vs distance. Expecting:

9NM -- 2700ft

8NM -- 2400ft

7NM -- 2100ft

So, 300 ft descent per NM

 

This is not only so in FS(X), it is how a glideslope works in real life too.

 

Note(1): Not every glideslope is 3.3 degrees in real life, but I think in fsx most are that angle.

Note(2): A glideslope is a signal that is sent up into the air from a transmitter that is located at the runway. The signal is recieved by the aircraft and the autopilot the follows that signal.

 

hope that helps.

[sIGPIC][/sIGPIC]
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Using the APP button is too easy and cheating if you ask me. If you have very low visibility then the APP button should be used. But for the most part you should be able to bank left and right by 5 degree intervals and pitch up and down slightly to adjust your flight path on the glideslope manually. Keep an eye on the VS to ride the glideslope down. Should be between 600/800.

 

It's good practice so when the APP button cops out you can fly the ILS manually. In my case with the F-22 Raptor, I have a backup WASS that gives me a fictitious LOC and GS based on the Mag of the runway so in case my APP cops out I have that. It's also great to use with runways with no ILS, at night, or low visibility at runways with no ILS. Actually, I have two WAAS gauges. One is the SALS and the other is in my VC panel. I've uploaded a vid here going to Catalina using the SALS.

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Relative to the OP's initial post ,

 

1. there are two aspects relating the ILS , range and capture .

2. the ILS is a short range Radio Navigation Aid , it's maximum range is about 25 nm .

3. capture is the moment when the aircraft intercepts and captures the Glideslope .

4. Generally most Glideslopes are 3.00 degrees or close to that value , there are some exceptions

such as ,

ILS Glideslopes greater than 3.0°,

London City (EGLC) is 5.5°, Chambéry (LFLB) is 4.46°, Innsbruck (LOWI) 4.0°, Lugano (LSZA) 6.65°.

 

5. to see the actual heading axis of the ILS refer to either , ILS approach plate (chart) , or where you don't have a chart refer to the GPS unit or the FS Flight Planner map , both have the ILS green feathers , green cones pointing to the ILS touchdown spot or aimpoint .

The beauty of the Flight Planner map is that by hovering the mouse on the green feather you get a dialogue box with ILS frequency and runway heading for entry to instruments , also if you place the mouse on the airport you get the Runway Elevation , and that is important as your initial approach height is always height above the Runway .

 

You always intercept the ILS Glideslope from underneath ,

for example , on autopilot you need to be level at 2,500' above the airport elevation with your heading as close as possible to the runway heading , at between 7 to 15 nm from the airport runway switch the autopilot to APP (Approach mode) , the aircraft will continue to fly at a level height until it intercepts/captures the Glideslope , it will then automatically descend down the Glideslope to the required runway .

 

Note ; distance from the runway can be determined by reference to the GPS unit taking into account the set zoom of the map display .

 

Cheers

Karol

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ILS Glideslopes greater than 3.0°,

London City (EGLC) is 5.5°, Chambéry (LFLB) is 4.46°, Innsbruck (LOWI) 4.0°, Lugano (LSZA) 6.65°.

Probably no real good place for this, but Javier's Nimitz V2 has a 4.38° slope, using Jivko Rusev's HUD. So do several others. The RFN gauges give different glideslopes for some of the carriers.

 

I just wanted to throw that in.

The exceptions that prove the rule, sort of...

Pat☺

[sIGPIC][/sIGPIC]

Had a thought...then there was the smell of something burning, and sparks, and then a big fire, and then the lights went out! I guess I better not do that again!

Sgt, USMC, 10 years proud service, Inactive reserve now :D

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http://www.navfltsm.addr.com/ils.htm

 

All you need to understand.

 

A good read. Localiser 18nm, glide slope 10nm. I guess Mr Zippy's "magic" was closest [emoji39]

 

I always fly jets for a VA so very familiar with ILS approaches. I just couldn't reconcile LittleNavmap 27nm - the value must have come from somewhere.

 

Moot point about "cheating" with autopilot on approach as I've watched YouTube real life commercial jets disengage on minimums or at point of intercept.

 

Thanks all.

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\

 

Moot point about "cheating" with autopilot on approach as I've watched YouTube real life commercial jets disengage on minimums or at point of intercept.

 

Thanks all.

 

It's NOT moot at all. By the time you get minimums you'll most likely will see the runway and are about to land in about 10 seconds. The idea being is that you maintain LOC and GS manually all the way to final manually. South West has their pilots do just this.

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The minimum is the lowest height that you can use the ILS to legally .

At the published minimum height you must be able to see the Runway visually , if you cannot see the runway due to fog at that height then you must conduct a missed approach , ie, go around .

 

The minimum height is dependant on various ILS categories , each category has it's own published minimum height .

Each ILS category is dependant on the standard of ILS equipment fitted to that aircraft , and on the training standard and approval of the pilot concerned .

 

Flying the ILS is like flying the aircraft within the confines of a cone that converges to a point at the ILS aimpoint on the runway , if you consider that you will realise that it bocomes more sensitive the closer you get to the runway .

It becomes so sensitive when very near the runway that if flown manually any small indication of the ILS deviation bars results in it being greater than the pilot's reaction times , at that stage if you try to chase the needles (ILS deviation bars) it results in PIO (Pilot Induced Occilations) , so usually close to touchdown the usual is to go visual .

 

Cheers

Karol

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To avoid confusion, it helps if you use correct terminology.

 

The idea being is that you maintain LOC and GS manually all the way to final manually.

 

All the way to final? You will likely be on final before GS capture, so how do you follow it all the way to final?

 

The minimum is the lowest height that you can use the ILS to legally .

At the published minimum height you must be able to see the Runway visually , if you cannot see the runway due to fog at that height then you must conduct a missed approach , ie, go around.

 

That is not true. The DH (Decision Height) (200 ft AGL for a CAT I approach) is the lowest you can go without seeing the runway environment, which include approach lighting. If you see the lighting, and not the runway, you can descend to 100 ft before you are required to go missed if you cannot see the runway.

 

The minimum height is dependant on various ILS categories , each category has it's own published minimum height .

Each ILS category is dependant on the standard of ILS equipment fitted to that aircraft , and on the training standard and approval of the pilot concerned.

 

No, ILS category determination is dependent on the ground equipment.

 

 

The idea being is that you maintain LOC and GS manually all the way to final manually. South West has their pilots do just this.

 

You seem to know a lot about WN ops. I am curious as to your source of info. Do you work there?

 

peace,

the Bean

WWOD---What Would Opa Do? Farewell, my freind (sp)

 

Never argue with idiots.

They drag you down to their level and beat you with experience

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That is not true. The DH (Decision Height) (200 ft AGL for a CAT I approach) is the lowest you can go without seeing the runway environment, which include approach lighting. If you see the lighting, and not the runway, you can descend to 100 ft before you are required to go missed if you cannot see the runway.

 

No, ILS category determination is dependent on the ground equipment.

 

peace,

the Bean

# 1.

Was correct , check the regs .

DH = minimum height .

There are several categories not just CAT I , and each CAT has a legal published DH/Min Ht .

#2.

Wrong , as I previously stated Different CAT is dependant on ILS equipment fit and aircrew qualification .

 

Cheers

Karol

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To avoid confusion, it helps if you use correct terminology.

 

 

 

All the way to final? You will likely be on final before GS capture, so how do you follow it all the way to final?

 

I mean all the way to landing. I had my terminology wrong.

 

 

 

 

 

Doing a quick Google search, I couldn't find Info. on how South West trains. But I have read that they are required to fly the ILS manually per company policy. You'll just have to take my word for it.

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#2.

Wrong , as I previously stated Different CAT is dependant on ILS equipment fit and aircrew qualification .

 

So you are saying that if my plane is properly equipped and my crew is properly trained I can fly to CAT III minima at an airport that has only a CAT I approach available?

 

peace,

the Bean

WWOD---What Would Opa Do? Farewell, my freind (sp)

 

Never argue with idiots.

They drag you down to their level and beat you with experience

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So you are saying that if my plane is properly equipped and my crew is properly trained I can fly to CAT III minima at an airport that has only a CAT I approach available?

 

peace,

the Bean

 

No .

You need to be a IFR rated Pilot .

You need to understand IFR procedures and rules/regulations .

You need to be Qualified to use the particular ILS CAT that you are using .

You must be current .

You must have a copy of the specific ILS Plate (chart) in the cockpit , and you have to pre brief it's

procedures and data contained on that Plate , the Plate will list specifics for various ILS CAT approaches .

The Plate will specify ,

" SPECIAL AIRCREW & ACFT CERTIFICATION REQUIRED "

 

So in summary , you can only fly a CAT III if the Approach Plate specifies that CAT III is available for that Airport/Runway and conditions detailed on Plate are satisfied .

 

The upside is that in the Flight Simulator we can do what ever we desire , we can fly by the strict application of the rules , or operate to our own rules .

The Flight simulator is awesomely flexible in that regard , lots of fun , and lots to learn .

 

Cheers

Karol

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Probably no real good place for this, but Javier's Nimitz V2 has a 4.38° slope, using Jivko Rusev's HUD. So do several others. The RFN gauges give different glideslopes for some of the carriers.

 

I just wanted to throw that in.

The exceptions that prove the rule, sort of...

Pat☺

Carriers in real life do not have an ILS, though they have systems that, to a pilot, act in a similar fashion. They have to compensate for ship motion in six degrees of freedom as well as the very small tolerance required to have a hook touchdown point that is approximately 120 by 50 ft. in order to successfully catch a wire. The visual glideslope is actually far more sensitive than say a PAPPI or VASI.

 

Carrier glide slopes are steeper, but are somewhat compensated for by the wind over deck, typically 25 knots today. This makes the actual glideslope angle / rate of descent smaller than one would initially perceive. However, to the pilot, visually, it does appear considerably steeper; especially since the painted "ladder lines" which define the lateral edges of the angle deck toe in from the ramp to the end of the angle deck. This effect is especially noticeable at night.

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This is an example of an ILS Approach plate ,

YMML (Melbourne , Australia) ILS CAT II and III.

 

Note Detail at bottom of the Plate/Chart .

 

click 3 times on chart to zoom in detail .

 

Cheers

Karol

ILS CAT II AND III.jpg

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I don't understand the attitude of "autopilot is cheating." I see that in the Kerbal Space Program forums too - a bunch of people who think if you don't hand-fly your rocket you're a cheater. Well, NASA has never launched a rocket that wasn't on autopilot for ascent and descent (with the sole exception of the shuttle which was hand-flown in the last couple of minutes), so if doing it the way NASA does it is cheating, I guess I'll be a cheat.

 

Same thing with flight sims - real pilots use the autopilot. They even use the appr button. Yes, real pilots also hand-fly the ILS, and so do I sometimes, but I'll also point out that real 747 pilots have a copilot to handle some of the workload, while we have to do everything solo.

 

So yeah, if everything's going smoothly I'll hand-fly the ILS, but if I'm dealing with storms on an approach into an airport surrounded by mountains, and having to respond to the slow ATC with its associated cockpit-visual-blocking popup, I'm probably gonna let the autopilot do its job. ;)

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I don't understand the attitude of "autopilot is cheating." I see that in the Kerbal Space Program forums too - a bunch of people who think if you don't hand-fly your rocket you're a cheater. Well, NASA has never launched a rocket that wasn't on autopilot for ascent and descent (with the sole exception of the shuttle which was hand-flown in the last couple of minutes), so if doing it the way NASA does it is cheating, I guess I'll be a cheat.

 

Same thing with flight sims - real pilots use the autopilot. They even use the appr button. Yes, real pilots also hand-fly the ILS, and so do I sometimes, but I'll also point out that real 747 pilots have a copilot to handle some of the workload, while we have to do everything solo.

 

So yeah, if everything's going smoothly I'll hand-fly the ILS, but if I'm dealing with storms on an approach into an airport surrounded by mountains, and having to respond to the slow ATC with its associated cockpit-visual-blocking popup, I'm probably gonna let the autopilot do its job. ;)

 

shadowfaxcrx - Thank you, I couldn't agree more. For those making comments about autopilot is cheating, I don't pay any attention to those kind of remarks. Just this morning there was an article on the internet that 3-4 major airline carriers and their respective unions have said "NO" to one man cockpits! Why, there is a lot going on in that cockpit, and a whole lot of responsibility for the many passengers' safety, and I couldn't agree more! Are they cheating, no, they are just using systems that were afforded to them for a reason!

 

When flying the larger jetliners in FSX, I always fly using an ILS, actually in all reality, it is called a "localizer only" approach, VFR! I ride out the glide scope until 600' AGL, then turn of AP and APPR, 500'

I turn off AT, so basically flying manually the last 600' - 500'. Am I cheating? You call it what you want "it is what it is" in MY cockpits!

 

Have a nice day and safe flight! Rick :cool:

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So in summary , you can only fly a CAT III if the Approach Plate specifies that CAT III is available for that Airport/Runway and conditions detailed on Plate are satisfied .

 

That CAT III approach will only exist if the airport has the proper ground equipment, which was my point when I stated " ILS category determination is dependent on the ground equipment.".

 

peace,

the Bean

WWOD---What Would Opa Do? Farewell, my freind (sp)

 

Never argue with idiots.

They drag you down to their level and beat you with experience

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Also,

 

No .

You need to be a IFR rated Pilot .

You need to understand IFR procedures and rules/regulations .

You need to be Qualified to use the particular ILS CAT that you are using .

You must be current .

You must have a copy of the specific ILS Plate (chart) in the cockpit , and you have to pre brief it's

procedures and data contained on that Plate , the Plate will list specifics for various ILS CAT approaches .

The Plate will specify ,

" SPECIAL AIRCREW & ACFT CERTIFICATION REQUIRED "

 

Is that not all covered by...

So you are saying that if my plane is properly equipped and my crew is properly trained I can fly to CAT III minima at an airport that has only a CAT I approach available?

 

...so, why would you say "no"?

 

peace,

the Bean

WWOD---What Would Opa Do? Farewell, my freind (sp)

 

Never argue with idiots.

They drag you down to their level and beat you with experience

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Also,

 

 

 

Is that not all covered by...

 

 

...so, why would you say "no"?

 

peace,

the Bean

 

No.

 

Systems on the airport need to be appropriate.

 

Systems om the aircraft need to be appropriate

 

Crew in the aircraft need to be trained.

 

The sim ONLY delivers the first two. You can be trained or a rank amateur as far as the third is concerned.

 

That's why you would say `no`. But it doesn't matter as far as the sim is concerned.

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shadowfaxcrx - Thank you, I couldn't agree more. For those making comments about autopilot is cheating, I don't pay any attention to those kind of remarks. Just this morning there was an article on the internet that 3-4 major airline carriers and their respective unions have said "NO" to one man cockpits! Why, there is a lot going on in that cockpit, and a whole lot of responsibility for the many passengers' safety, and I couldn't agree more! Are they cheating, no, they are just using systems that were afforded to them for a reason!

 

When flying the larger jetliners in FSX, I always fly using an ILS, actually in all reality, it is called a "localizer only" approach, VFR! I ride out the glide scope until 600' AGL, then turn of AP and APPR, 500'

I turn off AT, so basically flying manually the last 600' - 500'. Am I cheating? You call it what you want "it is what it is" in MY cockpits!

 

Have a nice day and safe flight! Rick :cool:

 

 

I don't understand the attitude of "autopilot is cheating." I see that in the Kerbal Space Program forums too - a bunch of people who think if you don't hand-fly your rocket you're a cheater. Well, NASA has never launched a rocket that wasn't on autopilot for ascent and descent (with the sole exception of the shuttle which was hand-flown in the last couple of minutes), so if doing it the way NASA does it is cheating, I guess I'll be a cheat.

 

Same thing with flight sims - real pilots use the autopilot. They even use the appr button. Yes, real pilots also hand-fly the ILS, and so do I sometimes, but I'll also point out that real 747 pilots have a copilot to handle some of the workload, while we have to do everything solo.

 

So yeah, if everything's going smoothly I'll hand-fly the ILS, but if I'm dealing with storms on an approach into an airport surrounded by mountains, and having to respond to the slow ATC with its associated cockpit-visual-blocking popup, I'm probably gonna let the autopilot do its job. ;)

 

 

 

 

 

It's a damn Sim so you're not going to have the work load like the real thing. And one should not soly depend on the auto pilot, but learn to fly manually. You don't enter a few thousand above to avoid an RA, now do you? You disengage and climb or descend.

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I don't use the AP hardly ever, except during the longer flights, when I need to use the head, or grab a cuppa. By the same token, I almost never fly tubes, either. I mostly fly fighters, modern or WWII prop jobs. I use the instrumentation of the ILS system, mainly the localizer and glideslope indications on the HSI, but I hand fly it. Why? I just enjoy doing it that way.

 

As has been pointed out, it's a simulator. Am I cheating, doing it "realistically", doing it all wrong, whatever? No, I'm doing it the way I enjoy doing it most. It's my copy, on my PC, with my joystick, so I'm going to fly and land the planes I want the way I want.

If another person want's to ONLY ever push tubes around by pushing buttons, then I say good for him! Someone else only wants to drive a J3 Cub up in Alaska, delivering mail to remote camps, more power to him. How someone uses their sim is their business, none of mine.

If I can help someone enjoy their sim better, great! But I'm not going to judge if what they're doing is right/wrong/other. As long as they're enjoying their sim, then to me, that's what matters. There may a best, or easiest, or most realistic way way to do something, but if someone want's to ignore all that, and do overhead recovery patterns in a 747, I hope it works well for them. And they don't pull the wings off or drive the landing gear up through the wings :D

 

But hey, all that's just me.

Have fun all!

Pat☺

[sIGPIC][/sIGPIC]

Had a thought...then there was the smell of something burning, and sparks, and then a big fire, and then the lights went out! I guess I better not do that again!

Sgt, USMC, 10 years proud service, Inactive reserve now :D

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So in summary , you can only fly a CAT III if the Approach Plate specifies that CAT III is available for that Airport/Runway and conditions detailed on Plate are satisfied .

 

That CAT III approach will only exist if the airport has the proper ground equipment, which was my point when I stated " ILS category determination is dependent on the ground equipment.".

 

peace,

the Bean

 

# 1 .

You must legally operate in compliance with the Approach Plate that you are using .

In the Plate that I posted it details various CAT II and CAT III details , so you can fly those ILS approaches as long as you fulfill the other conditions on that Plate .

Even though that Plate allows higher standard ILS , you cannot fly a lower standard CAT I ILS as it is not detailed on the Plate , you will see that CAT I is not listed and no DH is given .

Now if you find a different Plate that details a CAT I ILS for that airport/runway then you can do an ILS and you will be in compliance with that different Plate .

 

# 2 .

You refer to " proper ground equipment " , could you elaborate what additional ground equipment .

 

As far as I am aware CAT I , and CAT II , and CAT III have the same ground equipment comprising ,

** Glideslope transmitter and antenna .

and

** Localiser transmitter and antenna .

 

Both equipment elements have the same level of both precision and calibration .

They must be ultra reliant , and have emergency backup power in case of electrical grid failure .

 

The logic is that even at a CAT I level ILS approach you might have an airliner with anywhere from

100 to 400 passengers onboard flying in atrocious weather on ILS to a runway that probably will not be seen until a low height (DH) , you can see the safety implications that are applicable to all ILS approaches .

 

Cheers

Karol

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