ILS

[Baradium]

Ted (nice avatar!) and Baradium, thanks for the explanation.  I was told once that in Lugano airport (LSZA) who flies IFR doesn't have an ILS approach but an IGS. And I was told  (but I'm not IFR certified, so it could be I was misunderstood) that the rwy doesn't have an ILS but an IGS (instrumental ground system if I remember for what it stays correctly). when you say that in an ILS approach you have two needles that need to be centered, and in the LOC  you just have a guidance to the centerline, but it's up to you how to descent, it seems to me that it is what I was told to be the IGS approach, that doesn't give you the angle of descent you have to follow. the point is that, if I remember what I was told correctly, in that case there is no ILS components on ground but a different and easier (and less expensive) system............the point is that, from what you say, it seems that IGS doesn't exist, but is just a LOC approach on a ILS. So I'm wondering if I was completely misunderstood that day....

I'm looking into what IGS might stand for.  I'll get back to this post in a few minutes.   

But on that note... Happy, get into the chat room!   

[Baradium]

Ted (nice avatar!) and Baradium, thanks for the explanation.  I was told once that in Lugano airport (LSZA) who flies IFR doesn't have an ILS approach but an IGS. And I was told  (but I'm not IFR certified, so it could be I was misunderstood) that the rwy doesn't have an ILS but an IGS (instrumental ground system if I remember for what it stays correctly). when you say that in an ILS approach you have two needles that need to be centered, and in the LOC  you just have a guidance to the centerline, but it's up to you how to descent, it seems to me that it is what I was told to be the IGS approach, that doesn't give you the angle of descent you have to follow. the point is that, if I remember what I was told correctly, in that case there is no ILS components on ground but a different and easier (and less expensive) system............the point is that, from what you say, it seems that IGS doesn't exist, but is just a LOC approach on a ILS. So I'm wondering if I was completely misunderstood that day....

I'm looking into what IGS might stand for.  I'll get back to this post in a few minutes.   

But on that note... Happy, get into the chat room!   

Here is an approach plate for an IGS approach:

Text explaining it (note that there isn't a descent picture, this isn't a full plate).
http://www.lawrencechiu.com/kaitakairport/igs.htm   
This is an ILS with the glideslope offset from the runway by 47 degrees!  That's a hard turn at low altitude....

A night landing at that airport on the last night it was open
http://youtube.com/watch?v=McNU5b2-7bc

A day landing at the airport (gives a better idea of how the turn looks).
http://youtube.com/watch?v=zMpLaKJYxp8&mode=related&search=

[Ted_Stryker]

Ted (nice avatar!) and Baradium, thanks for the explanation.  I was told once that in Lugano airport (LSZA) who flies IFR doesn't have an ILS approach but an IGS. And I was told  (but I'm not IFR certified, so it could be I was misunderstood) that the rwy doesn't have an ILS but an IGS (instrumental ground system if I remember for what it stays correctly). when you say that in an ILS approach you have two needles that need to be centered, and in the LOC  you just have a guidance to the centerline, but it's up to you how to descent, it seems to me that it is what I was told to be the IGS approach, that doesn't give you the angle of descent you have to follow. the point is that, if I remember what I was told correctly, in that case there is no ILS components on ground but a different and easier (and less expensive) system............the point is that, from what you say, it seems that IGS doesn't exist, but is just a LOC approach on a ILS. So I'm wondering if I was completely misunderstood that day....

Thanks for the compliment on the avatar, happy   I have Stef to thank for that one, as it is his wonderful handywork    Thanks again Stef!!!!  Terrific job!!!

The only other thing I can think of with regard to "IGS" is Inertial Guidance System, but that's a system on-board spacecraft or aircraft, and not a system in use at an airport.  Inertial Guidance Systems depend on initialization of a known geographic point, then it uses a series of stabilized accellerometers to guage movement in a particular direct at a given rate or accelleration.  Such systems today are primitive compared to GPS, laser, or other autonomous navigation systems in use in aircraft spacecraft, and missile systems, though they do sometimes serve as backups in some devices.

[happylanding]

Thanks for the compliment on the avatar, happy   I have Stef to thank for that one, as it is his wonderful handywork    Thanks again Stef!!!!  Terrific job!!!

The only other thing I can think of with regard to "IGS" is Inertial Guidance System, but that's a system on-board spacecraft or aircraft, and not a system in use at an airport.  Inertial Guidance Systems depend on initialization of a known geographic point, then it uses a series of stabilized accellerometers to guage movement in a particular direct at a given rate or accelleration.  Such systems today are primitive compared to GPS, laser, or other autonomous navigation systems in use in aircraft spacecraft, and missile systems, though they do sometimes serve as backups in some devices.

I agree with you, the avatar is terrific. Great job, Stef! right!  I do not think is this one yet. but what I will do, is - as soon as I go back to lugano - ask again to the person who told me about the system. then I will get back with the information. it probably is something old, no more in use in the US!

[Ted_Stryker]

Thanks for the compliment on the avatar, happy   I have Stef to thank for that one, as it is his wonderful handywork    Thanks again Stef!!!!  Terrific job!!!

The only other thing I can think of with regard to "IGS" is Inertial Guidance System, but that's a system on-board spacecraft or aircraft, and not a system in use at an airport.  Inertial Guidance Systems depend on initialization of a known geographic point, then it uses a series of stabilized accellerometers to guage movement in a particular direct at a given rate or accelleration.  Such systems today are primitive compared to GPS, laser, or other autonomous navigation systems in use in aircraft spacecraft, and missile systems, though they do sometimes serve as backups in some devices.

I agree with you, the avatar is terrific. Great job, Stef! right!  I do not think is this one yet. but what I will do, is - as soon as I go back to lugano - ask again to the person who told me about the system. then I will get back with the information. it probably is something old, no more in use in the US!

I've been doing research to see if there are any references internationally on "IGS" being something in aviation other than what I stated below.  So far nothing... but if you want to read up on "IGS" (Inertial Guidance Systems) and "INS" (Inertial Navigation Systems), I've posted a link to an article I just foiund with some information below.  Enjoy!

http://www.centennialofflight.gov/essay/Evolution_of_Technology/navigation_tech/Tech33.htm

[Baradium]

I've been doing research to see if there are any references internationally on "IGS" being something in aviation other than what I stated below.  So far nothing... but if you want to read up on "IGS" (Inertial Guidance Systems) and "INS" (Inertial Navigation Systems), I've posted a link to an article I just foiund with some information below.  Enjoy!

http://www.centennialofflight.gov/essay/Evolution_of_Technology/navigation_tech/Tech33.htm

I feel like I'm in time out.   I hope I didn't offend you previously....


As I posted above, I found references to an IGS instrument approach for Hong Kong.  Being an ILS approach with a 47 degree offset from the runway due to obstructions, the turn to final is done at the MAP! 

That airport is now closed, I could not find *any* other references to an IGS system, however.    I did find multiple references to the system in Hong Kong by that name, so it does seem to have existed.

I have not been able to figure out what IGS stands for in the context used for Hong Kong's approach.  Happy's reasoning does make since to me though.

[Ted_Stryker]

I've been doing research to see if there are any references internationally on "IGS" being something in aviation other than what I stated below.  So far nothing... but if you want to read up on "IGS" (Inertial Guidance Systems) and "INS" (Inertial Navigation Systems), I've posted a link to an article I just foiund with some information below.  Enjoy!

http://www.centennialofflight.gov/essay/Evolution_of_Technology/navigation_tech/Tech33.htm

I feel like I'm in time out.   I hope I didn't offend you previously....


As I posted above, I found references to an IGS instrument approach for Hong Kong.  Being an ILS approach with a 47 degree offset from the runway due to obstructions, the turn to final is done at the MAP! 

That airport is now closed, I could not find *any* other references to an IGS system, however.    I did find multiple references to the system in Hong Kong by that name, so it does seem to have existed.

I have not been able to figure out what IGS stands for in the context used for Hong Kong's approach.  Happy's reasoning does make since to me though.

Offend moi?  No way!  I don't ever take offense to anyone imparting knowledge!  I found your post of great interest, and have been reading through yours as you've been making them.  I'm learning too!  In fact, that's the great thing about aviation is being able to learn from others and sharing knowledge    Never worry about speaking out!  We're all friends here, so no worries   

I do wonder if at that airfield, if it was an old military base for China, that the approach was published for those aircraft having such INS/IGS type of systems, which would likely be military in nature.   Just my thoughts on that as a possible explanation.   I know they have some military bases that used to use ground surveillance radar to assist with instrument approaches, though I think those went by a different designator, and was used strictly at military bases... at least from what I have heard.

[Baradium]

Offend moi?  No way!  I don't ever take offense to anyone imparting knowledge!  I found your post of great interest, and have been reading through yours as you've been making them.  I'm learning too!  In fact, that's the great thing about aviation is being able to learn from others and sharing knowledge    Never worry about speaking out!  We're all friends here, so no worries   

Thanks, I think I come off a bit strong sometimes.  I like debating stuff, I feel it's one of the best way to learn things.

I do wonder if at that airfield, if it was an old military base for China, that the approach was published for those aircraft having such INS/IGS type of systems, which would likely be military in nature.   Just my thoughts on that as a possible explanation.   I know they have some military bases that used to use ground surveillance radar to assist with instrument approaches, though I think those went by a different designator, and was used strictly at military bases... at least from what I have heard.

ASR/PAR approaches.  They just removed the ones for Eielson (near Fairbanks, prounounced similar to isle-son) from the civilian approach plates (seems it's been decommissioned).  Elmendorf (near Anchorage) still has its approach listed.  It's a cool system, I've never done one but have talked to those who have.  For PAR they use a higher grade radar and literally walk you through an ILS type of approach.   Initially they will instruct you to do all turns standard rate and then say "turn right.... stop turn"  to keep you on the approach course.   They will also give you instructions of above or below glideslope.   This happens all the way down.

PRECISION APPROACH RADAR- Radar equipment in some ATC facilities operated by the FAA and/or the military services at joint-use civil/military locations and separate military installations to detect and display azimuth, elevation, and range of aircraft on the final approach course to a runway. This equipment may be used to monitor certain nonradar approaches, but is primarily used to conduct a precision instrument approach (PAR) wherein the controller issues guidance instructions to the pilot based on the aircraft's position in relation to the final approach course (azimuth), the glidepath (elevation), and the distance (range) from the touchdown point on the runway as displayed on the radar scope.

Note: The abbreviation "PAR" is also used to denote preferential arrival routes in ARTCC computers.

Yes, I had to look all of this up.  ASR is the same thing except it doesn't give them elevation information, so they can't guide you down as low.  The PAR approaches get you down as far as an ILS!   That's pretty far for not having to use any of your own instruments other than a rate or turn indicator, altimiter and a VSI IMO!

The ASR approach for Elmendorf gets you to 461' agl, it doesn't have a diagram for descending, so I guess they give you step down fixes on the approach.

[Ted_Stryker]

IGS - Possible Definition!  Hoorah!

Well, I did some inquiries here with fellow pilots (military and otherwise), one of which actually has been in the cockpit jump seat of a plane on the KAI TAK IGS approach before!  Here is what I found out;

The term IGS originally was from a British system and it's equivalent today is basically a VOR-A with a circling approach to final in terms of what is meant by it and how it works.

IGS stands for Instrument Guidance System, and they are exceedingly rare.  Basically the definition published here already is correct.  It's an instrument approach to a point near the runway with an angle greater than 45 degrees to the approach end of the runway.  It is best flown like a circling approach with instrument, then visual guidance to the runway.

In the case of KAI TAK, the checkerboard is the point at the end of the instrument guidance where you make your turn to final, and do so visually at your planned decent rate.  According to my friend that was in the jump seat in a 747 doing this, it was a "fun" approach, but one that "wasn't too bad".  After seeing video of it, I'd have to say that while I wouldn't have a problem doing it in a light aircraft, I'd have really concerns about doing it in "big iron", but that's just me.  In good weather, okay, but in IMC, well... I'd rather not.  Call it a recognition of my limitations and experience if you will... or rather, my innate sense of self preservation

 Be careful out there


P.S.  While the Wikipedia is not necessarily authoritative due to lack of independent and verifiable auditing, my friend that flew the KAI TAK in that 747 jump seat also sent me this link.  The information is consistent with other things I've come up with independently... so I'd be inclined to say this entry is a good one.

http://en.wikipedia.org/wiki/Kai_Tak_Airport

[Ted_Stryker]

Offend moi?  No way!  I don't ever take offense to anyone imparting knowledge!  I found your post of great interest, and have been reading through yours as you've been making them.  I'm learning too!  In fact, that's the great thing about aviation is being able to learn from others and sharing knowledge    Never worry about speaking out!  We're all friends here, so no worries   

Thanks, I think I come off a bit strong sometimes.  I like debating stuff, I feel it's one of the best way to learn things.

I do wonder if at that airfield, if it was an old military base for China, that the approach was published for those aircraft having such INS/IGS type of systems, which would likely be military in nature.   Just my thoughts on that as a possible explanation.   I know they have some military bases that used to use ground surveillance radar to assist with instrument approaches, though I think those went by a different designator, and was used strictly at military bases... at least from what I have heard.

ASR/PAR approaches.  They just removed the ones for Eielson (near Fairbanks, prounounced similar to isle-son) from the civilian approach plates (seems it's been decommissioned).  Elmendorf (near Anchorage) still has its approach listed.  It's a cool system, I've never done one but have talked to those who have.  For ASR they use a higher grade radar and literally walk you through an ILS type of approach.   Initially they will instruct you to do all turns standard rate and then say "turn right.... stop turn"  to keep you on the approach course.   They will also give you instructions of above or below glideslope.   This happens all the way down.

PRECISION APPROACH RADAR- Radar equipment in some ATC facilities operated by the FAA and/or the military services at joint-use civil/military locations and separate military installations to detect and display azimuth, elevation, and range of aircraft on the final approach course to a runway. This equipment may be used to monitor certain nonradar approaches, but is primarily used to conduct a precision instrument approach (PAR) wherein the controller issues guidance instructions to the pilot based on the aircraft's position in relation to the final approach course (azimuth), the glidepath (elevation), and the distance (range) from the touchdown point on the runway as displayed on the radar scope.

Note: The abbreviation "PAR" is also used to denote preferential arrival routes in ARTCC computers.

Yes, I had to look all of this up.  ASR is the same thing except it doesn't give them elevation information, so they can't guide you down lower.  The PAR approaches get you down as far as an ILS!   That's pretty far for not having to use any of your own instruments other than a rate or turn indicator, altimiter and a VSI IMO!

Ah yes!!  ASR/PAR!!  I had forgotten what they were called!  Thanks!!    The first time I saw it accuratly depicted in it's use was, believe it or not, in the movie "Strategic Air Command" starring Jimmy Stewart.   I guess it helped that he was a real pilot and that movie was made in an era when they actually had great concern about making things more accurate when the actual military was involved in the making of the film.

Never be afraid to debate!  It's a wonderful learning tool, and so long as it's done with facts and things don't get personal on either side, I think it's terriffic!

The best thing one can do, in fact, is to debate and make people really research their standpoint and reach a factual conclusion.  In aviation it's always best to clear up ambiguities.... it saves lives ultimately   

Great research work on your part too!  I look forward to hearing more good posts and debates with you my friend!   

[Baradium]

Thanks for the IGS info Ted!  I couldn't find *any* reference other than what I posted to it.  I appears they are no longer used in the US?  Maybe they just call it by the approach name and leave it as that, a "circling" approach?

Ah yes!!  ASR/PAR!!  I had forgotten what they were called!  Thanks!!    The first time I saw it accuratly depicted in it's use was, believe it or not, in the movie "Strategic Air Command" starring Jimmy Stewart.   I guess it helped that he was a real pilot and that movie was made in an era when they actually had great concern about making things more accurate when the actual military was involved in the making of the film.

I've heard a lot about that movie, but never seen it.  I think I do remember seeing a WWII movie where they used a similar system to get down though, now that I think about it.

Never be afraid to debate!  It's a wonderful learning tool, and so long as it's done with facts and things don't get personal on either side, I think it's terriffic!

The best thing one can do, in fact, is to debate and make people really research their standpoint and reach a factual conclusion.  In aviation it's always best to clear up ambiguities.... it saves lives ultimately   

Great research work on your part too!  I look forward to hearing more good posts and debates with you my friend!   

Thank you, same here.

[Ted_Stryker]

Thanks for the IGS info Ted!  I couldn't find *any* reference other than what I posted to it.  I appears they are no longer used in the US?  Maybe they just call it by the approach name and leave it as that, a "circling" approach?

Ah yes!!  ASR/PAR!!  I had forgotten what they were called!  Thanks!!    The first time I saw it accuratly depicted in it's use was, believe it or not, in the movie "Strategic Air Command" starring Jimmy Stewart.   I guess it helped that he was a real pilot and that movie was made in an era when they actually had great concern about making things more accurate when the actual military was involved in the making of the film.

I've heard a lot about that movie, but never seen it.  I think I do remember seeing a WWII movie where they used a similar system to get down though, now that I think about it.

Never be afraid to debate!  It's a wonderful learning tool, and so long as it's done with facts and things don't get personal on either side, I think it's terriffic!

The best thing one can do, in fact, is to debate and make people really research their standpoint and reach a factual conclusion.  In aviation it's always best to clear up ambiguities.... it saves lives ultimately   

Great research work on your part too!  I look forward to hearing more good posts and debates with you my friend!   

Thank you, same here.

I'm not aware of any being used in the United States, and I've only heard of the one mentioned here in China.  In the USA we have offset approaches (obviously non-precision ones) with offsets like this.  A typical example of one is the VOR-A approach for Washington, Missouri airport, which has an offset that puts you at an angle that will basically take you across at midfield if you continue on to the missed and don't have the runway environment in sight to continue in visually.

I've included the approach plate for that one here just for an example.

 

[Baradium]

I'm not aware of any being used in the United States, and I've only heard of the one mentioned here in China.  In the USA we have offset approaches (obviously non-precision ones) with offsets like this.  A typical example of one is the VOR-A approach for Washington, Missouri airport, which has an offset that puts you at an angle that will basically take you across at midfield if you continue on to the missed and don't have the runway environment in sight to continue in visually.

I've included the approach plate for that one here just for an example.

 

Yeah, I was looking at those.  I noticed that the IGS is termed to have more than 45 degrees offset... that one is 35, but still not the 45 termed.  I was looking through the Alaska approach plates I have for the same thing and came up dry.  Are you aware of any US approaches with more than 45 degrees offset?

A big thing about that china one is that you are setup to make a turn to final instead of entering a modified traffic pattern like a normal circling approach.  Seems like it could be tough in low visibility...

[Ted_Stryker]

I'm not aware of any being used in the United States, and I've only heard of the one mentioned here in China.  In the USA we have offset approaches (obviously non-precision ones) with offsets like this.  A typical example of one is the VOR-A approach for Washington, Missouri airport, which has an offset that puts you at an angle that will basically take you across at midfield if you continue on to the missed and don't have the runway environment in sight to continue in visually.

I've included the approach plate for that one here just for an example.

 

Yeah, I was looking at those.  I noticed that the IGS is termed to have more than 45 degrees offset... that one is 35, but still not the 45 termed.  I was looking through the Alaska approach plates I have for the same thing and came up dry.  Are you aware of any US approaches with more than 45 degrees offset?

A big thing about that china one is that you are setup to make a turn to final instead of entering a modified traffic pattern like a normal circling approach.  Seems like it could be tough in low visibility...

I don't know of any in the continental US, though I did hear that there is one in Alaska that might, though it may have been obsoleted and replaced with something else already... most likely a GPS/RNAV.  According to the FAA regs here though, any approach with an offset greater than 30 degrees becomes a non-precision, circling approach with a sequential letter designator if multiple approaches, so even one with a 50 degree angle would still be classified as such and not termed an IGS here.  Again, this is my understanding of it.  Feel free to chime in anyone if I am incorrect in this please!

[Baradium]

IGS isn't in the AIM Glossary, so I agree that it appears that the term itself has been obsoleted and removed for use in the US.

I'd like to note that we have instrument approaches that don't get you below 2,000 ft AGL. 

Aantuvuk pass gets you to 3953' AGL on the NDB and the GPS gets you to 3353' AGL... and those are the only approaches.  As "circling" approaches with a 30 degree angle from one of the runways (same one for both), there are no runway numbers for the approaches. 

The airport is in the bottom of a pass (think a canyon).  Airport elevation 2107, terrain within a mile is almost 6,000!

Since you can fly up the canyon at 500 ft AGL, VFR traffic can get in under MUCH lower weather than IFR in this airport!  It's one of those places where you go somewhere else and fly VFR the rest of the way if the weather is *low*.

We don't go to that airport much, but my one room mate who flies a part 135 1900 gets to regularly.  Says it's pretty fun to be flying up the pass at low level at 200 kts.