Welcome, Guest. Please login or register.
Did you miss your activation email?
September 15, 2014, 10:57:38 PM
Home Help Login Register      
News: LiveATC.net Flyers Released!  Please click here to download & print a copy and be sure to post at an airport near you!


+  LiveATC Discussion Forums
|-+  Air Traffic Monitoring
| |-+  Listener Forum (Moderators: dave, RonR)
| | |-+  ILS / LOC Approaches
« previous next »
Pages: 1 2 [3] 4 Go Down Print
Author Topic: ILS / LOC Approaches  (Read 24481 times)
Unbeliever
Full Member
***
Offline Offline

Posts: 100


« Reply #30 on: April 02, 2008, 09:46:35 PM »

But what I was getting at is that if the GS is available further out than the 10nm intercept, you wouldn't only have the individual segments of the approach to use, but also the GS as well. Either one should suffice.


Drat, I need to go look for my references, but another board had a similar discussion, and that could get you in trouble.  I need to look myself since it involves math it might take a while. Some approaches had the GS dip below the intermediate segment min altitudes.  I think LAX was one of them.  One should always not fly the GS until you capture it at the GSIA.

Edit to add: Yup, it was LAX.  Both 25s ILSes put you 400ish feet too low at at least one fix.  25L at 3 degrees puts you at 4590 feet at GAATE (which is 15.2 miles out), which has a min altitude of 5000.  25R puts you at 4560 at FALLT (15.3 miles) who's min is 5000.

--Carlos V.
« Last Edit: April 02, 2008, 09:53:45 PM by Unbeliever » Logged
tyketto
Hero Member
*****
Offline Offline

Posts: 913


« Reply #31 on: April 03, 2008, 01:18:46 PM »

But what I was getting at is that if the GS is available further out than the 10nm intercept, you wouldn't only have the individual segments of the approach to use, but also the GS as well. Either one should suffice.


Drat, I need to go look for my references, but another board had a similar discussion, and that could get you in trouble.  I need to look myself since it involves math it might take a while. Some approaches had the GS dip below the intermediate segment min altitudes.  I think LAX was one of them.  One should always not fly the GS until you capture it at the GSIA.

Edit to add: Yup, it was LAX.  Both 25s ILSes put you 400ish feet too low at at least one fix.  25L at 3 degrees puts you at 4590 feet at GAATE (which is 15.2 miles out), which has a min altitude of 5000.  25R puts you at 4560 at FALLT (15.3 miles) who's min is 5000.

--Carlos V.

Could you compare that to the 24s? I'm wondering if it is because those coming in from the south or the west via the LEENA2 arrival going to the 24s may be vectored behind and above the 25 stream to keep the separation there through the gates.

This is good stuff all around! Smiley

BL.
Logged
keith
Sr. Member
****
Offline Offline

Posts: 272


WWW
« Reply #32 on: April 03, 2008, 02:47:53 PM »

There are folks here with much more flying experience than me, but as an instrument student, I've been taught (and have read) that the glideslope should be ignored until reaching the lightning bolt. Prior to that, you should use the minimum altitude published for each approach segment.

The fact that the glideslope might be received prior to the GSIA is irrelevant, and should be ignored (due to the false slopes that might exist, or due to published intermediate stepdown fixes along the way).

Here's a question I've had for a long time, and this seems like the best place to ask it...

Listening to the KSNA feed, the PTACs for the ILS 19R are usually done with reference to LEMON.  "4 from LEMON, fly hdg 160, maintain [MVA] until established, cleared ILS RWY 19R approach."  Given that the FAF for a precision approach IS the GS intercept point (SNAKE, in this case), and that the aircraft should join the localizer prior to the gate (which is outside SNAKE), why are they referencing LEMON instead of SNAKE?

The chart's here for anyone who wants to review it: http://204.108.4.16/d-tpp/0803/00377I19R.PDF

So, that's the question, why vector with reference to LEMON?

Logged

KS Flight Log - pics, videos, ATC/intercom audio and in depth flight reviews
PilotEdge - add ATC to your simulation experience
Jason
Hero Member
*****
Offline Offline

Posts: 1260


CFI/CFII


« Reply #33 on: April 03, 2008, 04:01:01 PM »

So, that's the question, why vector with reference to LEMON?

Many controllers reference the outer marker on the procedure (if one exists) in the PTAC, but it varies by facility.  I don't exactly know why, but I've heard this done all over the country in many different places.  If you ever listen to JFK Final, you can hear them doing it often as well.  I would imagine its for situational awareness since the outer marker and co-located intersection are more easily noted on the chart than another random fix on the approach, but you do bring up a good point that the lightning bolt is very close to/in reference of SNAKE intersection.

Also note that if ATC directs a lower-than-published glideslope/path intercept altitude, the resultant actual point of the glideslope/path intercept at the altitude authorized to maintain until established becomes the precision FAF.
« Last Edit: April 03, 2008, 04:07:49 PM by Jason » Logged
mk
Jr. Member
**
Offline Offline

Posts: 94



« Reply #34 on: April 03, 2008, 04:40:25 PM »

i'm gonna paraphrase the 7110.65 the ATC manual b/c i'm out of town for a few days but the FAA's 7110.65 definition of the FAF on an ILS is "the point the aircraft intercepts the glideslope".  most of the time the controller will give the lowest altitude restriction he can depending on his minimum vectoring altitude in the area.  He can clear you at the IAF if he wants as long as you are at or below the GS crossing altitude at that point.  at bwi, we clear anywhere from 4000' to 2000' on rwy 33L, but you'll notice that the altitude at RUETT is 1500'...we can only go to 2000' due to the MVA.  So, right there adds another mile out from the runway, plus a mile for the gate, plus 2 more miles to meet the 7110.65 requirements and you're now 8 miles from the runway...now if i clear you at 3000' for the ILS 33L, add 3.3 more miles to that...

as far as the question of whether or not a localizer or glideslope goes out  25 miles or whatever, just look at the chart...the IAF is most likely as far as the TERPS folks feels the GS is reliable. 
Logged
keith
Sr. Member
****
Offline Offline

Posts: 272


WWW
« Reply #35 on: April 03, 2008, 04:52:45 PM »

Jason,

I didn't ask the question very clearly. A distance from the marker is indeed very good for situational awareness. That's not my concern.  The issue is having the plane join the localizer inside the bolt...however, if the controller is allowed to throw away the lightning bolt, then I guess it works out Smiley
Logged

KS Flight Log - pics, videos, ATC/intercom audio and in depth flight reviews
PilotEdge - add ATC to your simulation experience
FlySafe
Newbie
*
Offline Offline

Posts: 35



« Reply #36 on: April 03, 2008, 05:19:01 PM »

The full published procedure is for approaches without RADAR assistance, it keeps you at a safe altitude prior to intercept.  (I should say Terminal radar assistance.)

When radar vectors are provided, we TRACONs can vector to intercept below the GS but not below the MVA.  If you get a close turn on (say at the gate) you will NOT have to chase the descent while achieving course guidance.  We (ATC) aren't ignoring the published procedure, it doesn't apply when ATC is involved (kind of an ATC shortcut).  But then you must be working with a TRACON.

For example, Enroute controllers who assume approach control airspace for part-time facilities normally do not have radar coverage to provided detail approach guidance below most altitudes, in my airspace sometimes traffic is not visible below 5000' for a sea level airport.  Their radar doesn't update as quickly, they cannot use mode C for separation etc, so they usually vector to an IAF or transition, Terminal controllers will vector (pending on the weather) closer and lower.
Logged

Natasha  
FAA-ATCT
Unbeliever
Full Member
***
Offline Offline

Posts: 100


« Reply #37 on: April 03, 2008, 05:34:58 PM »

  most of the time the controller will give the lowest altitude restriction he can depending on his minimum vectoring altitude in the area.  He can clear you at the IAF if he wants as long as you are at or below the GS crossing altitude at that point. 

Practically, as a pilot, if I'm getting vectors, and I become established and receive a "cleared for the approach" I will fly the lowest of 1) Assigned altitude or 2) min segment altitude.  I.e. assigned 3000, you vector me onto a segment that says 4000, the next segment is 2000, I will fly 3000 when cleared for the approach until I hit the 2000 segment.

Quote
as far as the question of whether or not a localizer or glideslope goes out  25 miles or whatever, just look at the chart...the IAF is most likely as far as the TERPS folks feels the GS is reliable. 

IAF? You mean precision FAF right?  The IAF can be anywhere and be based on navaids other than the localizer.

--Carlos V.
Logged
Unbeliever
Full Member
***
Offline Offline

Posts: 100


« Reply #38 on: April 03, 2008, 05:41:24 PM »


Could you compare that to the 24s?


Both Glideslopes appear to be above all previous min segment altitudes.  They're above JULLI and MERCE by 300 feet.

FYI: a 3% glideslope is 318 feet per nautical mile.  The rule of thumb for simplified cockpit calculations is 300 feet/nm.

--Carlos V.
Logged
Jason
Hero Member
*****
Offline Offline

Posts: 1260


CFI/CFII


« Reply #39 on: April 03, 2008, 05:48:24 PM »

Jason,

I didn't ask the question very clearly. A distance from the marker is indeed very good for situational awareness. That's not my concern.  The issue is having the plane join the localizer inside the bolt...however, if the controller is allowed to throw away the lightning bolt, then I guess it works out Smiley

I suppose I didn't answer it too clearly either.  As Natasha alluded to, the charted lightning bolt in practicality, is to be used if you've been cleared for the full approach (no VTF) outside of radar coverage.  Since ATC can change the intercept altitude to whatever they want (though it must be below the GS and above the MVA) the resultant point of the altitude assigned and the glideslope/glidepath intercept becomes the new precision FAF, and thus, the charted lightning bolt does not apply.
Logged
Unbeliever
Full Member
***
Offline Offline

Posts: 100


« Reply #40 on: April 03, 2008, 06:03:00 PM »

  As Natasha alluded to, the charted lightning bolt in practicality, is to be used if you've been cleared for the full approach (no VTF) outside of radar coverage.

Incorrect.  Even with VTF, the pilot should descend to the GSIA before following the glideslope.

For example, CNO ILS 26R that I got tons and tons of time in training.  SoCal usually gives us vectors to final at 3000 outside LINDN.  By coincidence, the GS intersects at LINDN right at 3000, and when I'm flying the needle does come down to center at that point.  HOWEVER, once I hit LINDN, I don't follow the GS down, but do a non-precision descent to 2100, and begin following the GS once it re-centers at DEWYE.  TERPS chose that point for a reason, and we as pilots don't know it.  The GS is not guaranteed out beyond the normal GSIA point so we have to fly it as charted.

Of course, if I'm below the GSIA when I am established on the FAC I'll start down at whatever point I intercept, but in practicality, I should never receive that since ATC is supposed to vector us at least a mile farther out from that point.  I have a copy of .65 at home that I'll look up for reference.

--Carlos V.
« Last Edit: April 03, 2008, 06:04:33 PM by Unbeliever » Logged
Jason
Hero Member
*****
Offline Offline

Posts: 1260


CFI/CFII


« Reply #41 on: April 03, 2008, 07:12:01 PM »

Incorrect.  Even with VTF, the pilot should descend to the GSIA before following the glideslope.

There is nothing that requires a pilot to descend to the GSIA before using the glideslope signal.  If ATC clears you for the approach 10 or 15 miles out, maintaining 1,000 feet above the GSIA (which is still below the glideslope), you have two options.  You can either maintain 3,000 feet until you intercept the glideslope, or you could descend down to the GSIA and intercept down there.  The only thing you can't do is descend below the minimum altitude for the prescribed route segment on the approach.  If you use Jepps, you'll notice the second method is depicted much more clearly than on the NACO charts (shown as stepdowns), but most commercial pilots (airline, corporate, fractional, etc) opt to remain at the altitude assigned by ATC until GS intercept since it provides a much smoother descent.

As long as ATC assigns an altitude below the glideslope and above the GSIA, you're cleared to remain at that altitude until you capture the glideslope.

Quote from: 7110.65S §5-9-1
b. For a precision approach, at an altitude not
above the glideslope/glidepath or below the
minimum glideslope intercept altitude
specified on
the approach procedure chart.
« Last Edit: April 03, 2008, 07:15:00 PM by Jason » Logged
mk
Jr. Member
**
Offline Offline

Posts: 94



« Reply #42 on: April 04, 2008, 11:26:51 AM »

no, carlos, i meant the IAF...it's my understanding along with numerous controllers i work with that the IAF is placed at it's location on each approach by the TERPS folks basically saying that this fix is as far out as the GS can be 100% trusted.
Logged
Unbeliever
Full Member
***
Offline Offline

Posts: 100


« Reply #43 on: April 04, 2008, 05:19:45 PM »

no, carlos, i meant the IAF...it's my understanding along with numerous controllers i work with that the IAF is placed at it's location on each approach by the TERPS folks basically saying that this fix is as far out as the GS can be 100% trusted.

Drat, the on-line version of TERPS is missing so many chapters I have to go to anecdotes instead of refrences.

To that point I present RAL ILS 9 as a counter-example.  SLI is an IAF and is 30 miles away, way off angle, roughly 35-40 degrees, and on the other side of a mountain (Pleasant's peak).  I doubt you can get either the localizer OR the glideslope from over SLI.  What SLI does have is a route segment that tells you how to get to the LOC.  From SLI is not a feeder route, it is a full blown IAF and intermediate segment of the approach.

And I can't provide a reference to intercepting at GSIA since both TERPS and whole chunks of Part 97 are not on line.  But to nitpick, 7110.65 5-9-1 is an instruction to controllers on where to put pilots on a VTF, not what the pilot is cleared to do.

The header to 5-9-1

Except as provided in para 7−4−2, Vectors for Visual
Approach, vector arriving aircraft to intercept the
final approach course:


And thanks, 5-9-1 (b) provided a reference to my statement that ATC isn't supposed to put you below GSIA either.

--Carlos V.
Logged
Jason
Hero Member
*****
Offline Offline

Posts: 1260


CFI/CFII


« Reply #44 on: April 04, 2008, 06:01:10 PM »

Drat, the on-line version of TERPS is missing so many chapters I have to go to anecdotes instead of refrences.

To that point I present RAL ILS 9 as a counter-example.  SLI is an IAF and is 30 miles away, way off angle, roughly 35-40 degrees, and on the other side of a mountain (Pleasant's peak).  I doubt you can get either the localizer OR the glideslope from over SLI.  What SLI does have is a route segment that tells you how to get to the LOC.  From SLI is not a feeder route, it is a full blown IAF and intermediate segment of the approach.

And I can't provide a reference to intercepting at GSIA since both TERPS and whole chunks of Part 97 are not on line.  But to nitpick, 7110.65 5-9-1 is an instruction to controllers on where to put pilots on a VTF, not what the pilot is cleared to do.

The header to 5-9-1

Except as provided in para 7−4−2, Vectors for Visual
Approach, vector arriving aircraft to intercept the
final approach course:


And thanks, 5-9-1 (b) provided a reference to my statement that ATC isn't supposed to put you below GSIA either.

--Carlos V.

There is no requirement of any sort in the federal aviation regulations that a pilot must descend to a minimum altitude on an instrument approach unless a mandatory altitude is published.  Of course, what I posted above also applies as well (a pilot may not descend below the minimum altitude for the prescribed route segment on the approach).  Rod Mochado also gave the same answer to a pilot whose friend's instrument student failed an instrument checkride for not descending to the GSIA on an ILS approach.

Since you brought it up, JO 7110.65S ยง5-9-1 absolutely does concern what altitude ATC may assign an aircraft when vectoring ato intercept the final approach course.  As I referenced in my last post, sub-para (b) of this section makes that distinction.  ATC may not vector an aircraft to intercept the FAC below the GSIA, or above the glideslope/glidepath at the point of interception.  If the altitude assigned meets this criteria, then the pilot may fly that altitude to capture the glideslope.
Logged
Pages: 1 2 [3] 4 Go Up Print 
« previous next »
Jump to:  


Login with username, password and session length

Powered by MySQL Powered by PHP Powered by SMF 1.1.19 | SMF © 2011, Simple Machines Valid XHTML 1.0! Valid CSS!