ILS

[Ted_Stryker]

Just had to chime in on this one....

While it's great to have the help of the autopilot on the approach, for safety sake, remember to practice without it's help.  Even the best autopilots malfunction... and being able to hand-fly an approach in a pinch is still a skill to hone.

Sorry if this sounds preachy... I just heard my CFII's voice in my head when I read this thread!   I couldn't resist passing his sage advice on.   I've had more than one KAP140 unit go south on me when it was least expected.

 

[Bustnthru]

its the gear down here mostly, the bigger AD's have lower DA's  AA, CH, WN, OH, but nothing like the auto land Stuff U guys got up there, after a quick flick thru the  AIP im pretty sure theres nothing better than a cat 1 in NZ  ( I will correct statment if im wrong)

[tundra_flier]

Basicly, if the glideslope goes out, you can still get to the airport with a localizer approach. 

How do you fly a localizer approach?  My plane has a VOR, but no glideslope reciever and I'd love to get my IFR rating, but not if I can't maintain it.  Also, No marker beakons, No ADF, but full gyros.  My next plane will definitly get an IFR GPS unit, but that's several years down the road.

Phil

[fireflyr]

Basicly, if the glideslope goes out, you can still get to the airport with a localizer approach.

How do you fly a localizer approach? My plane has a VOR, but no glideslope reciever and I'd love to get my IFR rating, but not if I can't maintain it. Also, No marker beakons, No ADF, but full gyros. My next plane will definitly get an IFR GPS unit, but that's several years down the road.

Phil

Crackers!  I wish you were closer, I'd love to show you (and get my hands on your airplane)but  one of the other CFIIs who teach on a daily basis could probably explain it more succinctly than I so lets see if we can sucker one in.

[Ted_Stryker]

Basicly, if the glideslope goes out, you can still get to the airport with a localizer approach. 

How do you fly a localizer approach?  My plane has a VOR, but no glideslope reciever and I'd love to get my IFR rating, but not if I can't maintain it.  Also, No marker beakons, No ADF, but full gyros.  My next plane will definitly get an IFR GPS unit, but that's several years down the road.

Phil

Well, I'm not a CFII, but I am working on my instrument ticket, so I'll try to shed some basic light on this, and hope that an actual CFII chimes in to fill in the blanks, and correct me (PLEASE!!!) if I'm not right.

You tune your VOR to the localizer frequency.  A localizer is 4x more sensitive than a regular VOR, so VERY small, gradual adjustments, sometimes only a nudge or bare kick of a rudder pedal is all that's needed if the needle, once centered, starts drifting.  You use your descent rate and time from a known fix to fly the approach in for the category of your airplane as it is classified on the approach plate, and, if all goes right, you should hopefully have the field in sight by the time the time is up.  If not, you execute the missed approach procedure.  I might add that unless you think you really screwed up the flying of the procedure, I wouldn't give it a second go at the same airport.  After all, if you missed it once, and flew it according to the proc, then you may as well go to your alternate, where the weather is better (if you've planned the flight out right).

Hope this helps.  I'd get with a qualified CFII to work on this.  DON'T do it on your own unless you are doing it under the hood with a safety pilot in VFR.  Trying it for real in IMC without lots and lots of practice is a good way to invite disaster.  (Ok... I know you probably knew that in this last paragraph, but I feel better for having said it in case someone else thinks they can give it a whirl)

 
Happy and SAFE flying!

[Baradium]

Good brief on it, Zaffex!  You are correct in how it works.

There are many components to the ILS system in total.  There is various forms of runway and approach lighting, different kinds of ILS "approaches" which use different kinds of radio navigation tools, and different kinds of procedures to handle different kinds of "approaches" too.

The approach is also only one area of Instrument flight.  There are "SID"s too.  An instrument "approach" is called a "STAR", which means Standard Terminal ARrival procedure.  A "SID" is a Standard Instrument Departure procedure.  It would literally fill a book on how all this stuff works, and now with GPS and WAAS coming into the picture the ILS systems are changing, and becoming available at airports not formally equipped with what has traditionally been known as an "ILS".

An Instrument Approach Procedure and a STAR are two different things.  A SID is also not the same as a regular departure procedure either.

A STAR (which is correctly a Standard Terminal Arrival) is for larger airports with higher amounts of traffic.  It's a standardized flow for aircraft to follow to line up for controllers.  The entire idea of this is that it makes it easier for controllers to vector you around afterwards for the approach.  For example, the entire point of the TAGER 3   STAR at Anchorage is that you go to the fix "TAGER" and then procede to the Anchorage VOR (you get vectored before reaching it, usually for an ILS). 

The STAR gets you to the Terminal Area, the Approach gets you to the ground.

A SID is the departure version of a STAR.  In both cases controllers are able to assign you to the procedure and know that you will make the neccesary course changes through the procedure.  This dramatically reduces the workload.

Like with the STAR and Instrument Approach (many airports have Instrument Approaches, but few have STARS),  some smaller airports have a departure procedure, but no SIDs.   Departure procedure would usually be for an obstruction, such as a mountain.  The SID is for traffic flow and controller workload.

I'm going to intersperse a few quotes from the AIM here:

"INSTRUMENT DEPARTURE PROCEDURE (DP)- A preplanned instrument flight rule (IFR) departure procedure published for pilot use, in graphic or textual format, that provides obstruction clearance from the terminal area to the appropriate en route structure. There are two types of DP, Obstacle Departure Procedure (ODP), printed either textually or graphically, and, Standard Instrument Departure (SID), which is always printed graphically. "

"STANDARD INSTRUMENT DEPARTURE (SID)- A preplanned instrument flight rule (IFR) air traffic control (ATC) departure procedure printed for pilot/controller use in graphic form to provide obstacle clearance and a transition from the terminal area to the appropriate en route structure. SIDs are primarily designed for system enhancement to expedite traffic flow and to reduce pilot/controller workload. ATC clearance must always be received prior to flying a SID. "

"STANDARD TERMINAL ARRIVAL- A preplanned instrument flight rule (IFR) air traffic control arrival procedure published for pilot use in graphic and/or textual form. STARs provide transition from the en route structure to an outer fix or an instrument approach fix/arrival waypoint in the terminal area. "

When someone is referring to an ILS generically, they are generally referring to what is known as a "localizer" in conjunction with an on-airport "VOR"  The VOR portion provides left-to-right guidance, while the "localizer" provides the vertical slope, or glide slope, information.  So, when you are on a full "ILS" approach, you are really using two different radio signals to guide you down.  There are other ways for finding the airport too.  There are Ground Surviellance Radar approaches (widely used by the military in conjunction with a "GNC" officer), NDB approaches, which use the ADF radio (these are going away), and GPS now too.  As I said... there are plenty of things I could write about here to explain all of it, but I'm not a CFI, and it would take a book, literally, to deal with the topic.

Someone previously corrected the ILS components (I want to make sure it is clear that the localizer and a VOR are two different devices that work in very different ways).  The radar approaches are becoming fewer and farther between now.  Few controllers can provide it, and I've only seen military bases listing it (and not all of them).

The thing to also know is that the ILS system is a term generally used to denote the entire range of Instrument approach and departure procedures colloquially, while flying an actual "ILS" is dealing with the two different, high precision, radio beams providing horizontal, and vertical navigation information.  Oh, and yes, you can have an "ILS" that does not provide glide-slope information.  In cases like that, the procedure is to use speed, and time from known points to plan decent rates so you end up where you are supposed to be.

You could know that, but it is incorrect.  ILS is a very specific term denoting a single system that has both vertical and horizontal guidance.  And *no* you can *NOT* have an ILS with no glide slope information.  In that case it's a LOC or Localizer approach and not an ILS.   Now, the ILS charts will have a LOC depiction and MDA for use with no glide slope, but it is still a different approach.  An approach with no glideslope installed is simply termed a Localizer approach or LOC.

Ok... I suspect this has totally confused many at this point... so I'll stop here.   

I hope I havn't offended you with my corrections here.  Those are very common misconceptions about how the IFR environment works.

[Baradium]

Phil, it sounds like your aircraft isn't IFR certified.  With a single VOR and no other nav aids, I'm fairly positive it's not. 

You'd be better off getting into an actual IFR aircraft to learn approaches etc.

[tundra_flier]

Phil, it sounds like your aircraft isn't IFR certified.  With a single VOR and no other nav aids, I'm fairly positive it's not. 

You'd be better off getting into an actual IFR aircraft to learn approaches etc.

Thanks, I've been flying as Safty pilot for a friend of mine this summer and learned a lot about IFR flying.  It would theoretically be possible to fly the LOC approach in my plane, but not very practical.  Since my Nav doesn't even have flip-flop capability it'd be very tough to find CASH and stay on the LOC.  But then, the missed approach procedure requires an ADF, so your right, I'd have to do some upgrades.  That's why I'm holding off untill I have a plane I can stay current in.

Phil

[Baradium]

Thanks, I've been flying as Safty pilot for a friend of mine this summer and learned a lot about IFR flying.  It would theoretically be possible to fly the LOC approach in my plane, but not very practical.  Since my Nav doesn't even have flip-flop capability it'd be very tough to find CASH and stay on the LOC.  But then, the missed approach procedure requires an ADF, so your right, I'd have to do some upgrades.  That's why I'm holding off untill I have a plane I can stay current in.

Phil

Phil, it's CACHE. 


An IFR GPS is a very nice addition as well.  It makes an very large difference in your flying.  GPS approaches help situational awareness and you can still watch the moving map on others (and many fixes are in the GPS units).  You can fly airways with a course line or get a clearance directly to your destination.


IFR aircraft also require updates (for GPS units) and checks for various equipment.  This includes the NAV radios and instrumentation.

[tundra_flier]

An IFR GPS is a very nice addition as well.

It's also a $10,000 addition!    So not happening any time soon.  Maybe when the price drops to less than 50% of the plan's value.

Phil

[Baradium]

An IFR GPS is a very nice addition as well.

It's also a $10,000 addition!    So not happening any time soon.  Maybe when the price drops to less than 50% of the plan's value.

Phil

Hahahaha!

We use King/Bendix  KLN-90Bs in the 1900s, they are a popular unit because they are so capable yet not very expensive (relatively speaking).  Is that $10,000 price tag for a KLN-90B or a pricier unit?

[happylanding]

You could know that, but it is incorrect.  ILS is a very specific term denoting a single system that has both vertical and horizontal guidance.  And *no* you can *NOT* have an ILS with no glide slope information.  In that case it's a LOC or Localizer approach and not an ILS.   Now, the ILS charts will have a LOC depiction and MDA for use with no glide slope, but it is still a different approach.  An approach with no glideslope installed is simply termed a Localizer approach or LOC.

Gosh, professional description!
 
but now I have a question: is the LOC the IGS?!? if not, where is the difference?

[Ted_Stryker]

You could know that, but it is incorrect.  ILS is a very specific term denoting a single system that has both vertical and horizontal guidance.  And *no* you can *NOT* have an ILS with no glide slope information.  In that case it's a LOC or Localizer approach and not an ILS.   Now, the ILS charts will have a LOC depiction and MDA for use with no glide slope, but it is still a different approach.  An approach with no glideslope installed is simply termed a Localizer approach or LOC.

Gosh, professional description!
 
but now I have a question: is the LOC the IGS?!? if not, where is the difference?

By "IGS" are you meaning "ILS" ?  I think what is important to convey is that there is a difference between generic terms of flying on instruments in an IFR approach environment, and the actual specific types of approaches.  A true "ILS" approach had both vertical and horizontal guidance by way of radio signals.  The actual glide slope needle is employed in a true ILS for vertical guidance down on the approach.  If you are flying on an ILS approach and the vertical guidance goes out on you, then the ILS approach turns into a Localizer approach.  A LOC (Localizer) approach gives you the guidance onto the centerline, but you guage your approach to the MAP (Missed Approach Point) by use of the time for the category your are flying in on (A, B, C, etc., which is based on ground speed).

One should fly an ILS and back up the GS indication with the clock too, in case you need to revert to the LOC approach.  That way if it quits while you're halfway down, you'll know how much time is left to go until the MAP where you either have to go missed, or land.

[Baradium]

By "IGS" are you meaning "ILS" ?  I think what is important to convey is that there is a difference between generic terms of flying on instruments in an IFR approach environment, and the actual specific types of approaches.  A true "ILS" approach had both vertical and horizontal guidance by way of radio signals.  The actual glide slope needle is employed in a true ILS for vertical guidance down on the approach.  If you are flying on an ILS approach and the vertical guidance goes out on you, then the ILS approach turns into a Localizer approach.  A LOC (Localizer) approach gives you the guidance onto the centerline, but you guage your approach to the MAP (Missed Approach Point) by use of the time for the category your are flying in on (A, B, C, etc., which is based on ground speed).

One should fly an ILS and back up the GS indication with the clock too, in case you need to revert to the LOC approach.  That way if it quits while you're halfway down, you'll know how much time is left to go until the MAP where you either have to go missed, or land.

I can't find anything to disagree with here, great explanation.


There are also BC LOC approaches!  Back Course Localizer approaches are usually for the other runway direction opposite a localizer or ILS approach, with a standard CDI you read it backwards to do the approach (we have an HSI so we just turn the needle around the opposite way and it works normally).  These days it's rare to see a regular LOC approach that isn't just part of an ILS, although we have a few hiding out up here in Alaska I believe.  The directional part of an ILS is still called a Localizer and it's the same equipment, the only difference is the addition of a glide slope transmitter beside the touchdown zone. 

There are also ILS DME and LOC DME approaches which use DME fixes for the approach (we have some of those too).   

I've been on a ILS VOR DME approach since I've been up here.  You shoot a DME arc off of the VOR until a set VOR radial when you start your turn inbound  to end up on the Localizer at X altitude until you intercept the glideslope down (in a smaller aircraft it lets you use one receiver if only one is availible to shoot the arc and do the turn inbound, with faster aircraft you need the ID just so you don't overshoot the localizer, and it still comes up quick).

An approach that is ILS DME or LOC DME is nice because if you don't start time and the DME is up you still have your MAP information if the glideslope is out.  There are also NDB DME approaches up here still, although I've only shot one NDB approach due to an INOP GPS.  We shoot GPS or ILS approaches when we can, and I'm not aware of any airports that we go to now that have any instrument approaches that don't have a GPS.

Tundra:  another reason for an IFR GPS, there are many airports now that *only* have a GPS approach.

Anyway, a key thing to know about a Localizer (for LOC or ILS approaches) is that they actually use a different method to determine where the needle points than the VORs do.  On a VOR the receiver times pulses while on an ILS the signal is a left of course signal or right of course signal, the instrument measures how much of each signal you are picking up, both is on course.  At least that's the simplist way to explain them.

Since I brought up a VOR... imagine a compas spinning.  The needle has a laser that points out in whatever direction the needle is pointing.  As the needle gets to 0 degrees (magnetic north) there is a "pulse" of light that comes out.  Turn those into radio signals and that's what a VOR does.  The receiver measures the difference in the time between the 0 pulse and the line pulse to determine what radial you are on.

Because an ILS just says right or left of course it'll show the same no matter how you have the receiver set for a VOR... although that could get really confusing on an HSI (an HSI is an adjustable arrow in your DG, the point of the arrow is the VOR radial and the center of the arrow moves left or right for course).

Too much info?

[happylanding]

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....