Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

Initial Approach Fixes, FAFs and a rant!

Wikiposts
Search
Tech Log The very best in practical technical discussion on the web

Initial Approach Fixes, FAFs and a rant!

Thread Tools
 
Search this Thread
 
Old 11th Mar 2010, 14:40
  #1 (permalink)  
Thread Starter
 
Join Date: Apr 2008
Location: India
Posts: 8
Likes: 0
Received 0 Likes on 0 Posts
Initial Approach Fixes, FAFs and a rant!

Hi Folks,

Just did a trip today with a check airman, and got into 'discussion' He was of the opinion that an IAF need not be published on an approach plate. My argument was that it has to be published. My logic being that an IAF is basically a transition from the enroute environment, to the terminal environment. To which his response was what if the controller clears you to intercept the localizer from present heading and clears you for the approach. My question is what if you're lost comms, where do you commence the approach from, before flying the full approach? Im just a first officer monkey in the right seat, so am I talking through my hat? I pulled out some random approach plates to show him that every instrument approach has a published IAF, to which he asked me if I was testing him... But thats a whole 'nother story! Help me out here guys!
FlyBoyFloyd is offline  
Old 11th Mar 2010, 22:01
  #2 (permalink)  
 
Join Date: Jun 2006
Location: Europe
Posts: 716
Likes: 0
Received 0 Likes on 0 Posts
I can help you with the ICAO definition of "Approach Procedure" according to "From Takeoff to Landing: design criteria for instrument flight procedures" (Åkerlind 1994):

[i]A series of predetermined manoeuvers by reference to flight instruments with specified protection from obstacles from the initial approach fix, or where applicable, from the beginning of a defined arrival route[/b] to a point to which a landing can be completed and there-after, if a landing is not completed, to a postion at which holding or en-route obstable clearance critera apply.[i] (my bold)

According to the same book, which explains PANS-OPS, [i]an approach procedure is divided into maximum five segments, when possible each segment beginning and ending at a fix. However, only those segments required by local conditions are included in the procedure[i] (again my bold)

And I fully buy your checkers ILS argument. Yes, there might be an IAP for that airfield that you would go to, but not nescesarily for that specific approach. Without having any of my plates here, I believe I somewhere, sometime saw some ILS approaches to a big airport with pretty much only the ILS symbol drawn in, the initial missed approach going straight ahead and some big writing saying "expect vectors to final" or something to that effect, but I stand to be corrected on that one.
bfisk is offline  
Old 11th Mar 2010, 22:12
  #3 (permalink)  
 
Join Date: Jun 2006
Location: Europe
Posts: 716
Likes: 0
Received 0 Likes on 0 Posts
For some reason I'm unable to edit my post for the correct tags above, but you catch my drift.

Wrt that approach plate, take a look at the Dallas Forth-Worth 35R Cat III ILS approach: http://naco.faa.gov/d-tpp/1002/06039I35RC3.PDF
It's got no IAF!
bfisk is offline  
Old 11th Mar 2010, 22:29
  #4 (permalink)  
 
Join Date: May 2007
Location: Alaska
Posts: 147
Likes: 0
Received 2 Likes on 2 Posts
Floyd, you're both right. If an IAF is designated, then it must be published. But if ATC gives you vectors onto final, then there is no requirement for you to fly over the IAF; as long as you're in radar contact and getting vectors onto final, you are relieved of the duty to cross an IAF and fly any procedure turns that may be depicted. Bfisk raises an interesting point however; approaches to major airports don't have IAFs published, because it's assumed that tower and approach operate 24/7/365, you will always be under radar contact and will always get vectors onto final whether you want them or not. But then what if you have a comm failure in IMC, while enroute to a major airport? Assuming you remain in IMC all the way, then you have no choice but to continue to the intended destination, and get yourself onto an approach any way can, depending on your navigational capabilities. ATC will shut down the entire airspace for you, since they won't know which approach to which runway you are planning. Therefore, I expect they want you to just get onto the ground ASAP, by any available means, without worrying about trivial details such as IAFs. If you have GPS, proceed direct the OM. If not, use the LOC DME to arc to the OM. Or pull out the enroute chart, find any navaid your A/C is capable of receiving and plot a rough course to the OM. Get on the ground asap and don't hit anything, and everything else is just paperwork.
Caboclo is offline  
Old 11th Mar 2010, 23:27
  #5 (permalink)  
 
Join Date: May 2007
Location: UK
Age: 40
Posts: 115
Likes: 0
Received 0 Likes on 0 Posts
Hi FlyBoyFloyd

On first reading I'd say your right. All instrument approaches should have an IAF.

Sadly after doing research it seems that PAN-OPS (I guess you work to the US TERPPS critera) say that an approach MAY have 5 segments.

ARRIVAL, INITIAL, INTERMEDIATE, FINAL, MISSED APPROACH

Checking the UK AIP EGLL London Heathrow 09L ILS/MLS approach plates there doesn't seem to be an IAF just a FAP.

So it seems he's right. But not for the logic he thought.

Learn't something new. Cheers
Sleepybhudda is offline  
Old 11th Mar 2010, 23:36
  #6 (permalink)  
 
Join Date: Jun 2006
Location: Europe
Posts: 716
Likes: 0
Received 0 Likes on 0 Posts
Just because one IAP at an airport doesn't have an IAF, doesn't mean all the IAPs at that place will lack IAFs. When radar vectoring is used for say 95% of the time, it doesn't make sense to publish 10 approaches with routes that will never be flown, if it is quite sufficient with 1 or 2 full procedures to be flown in case of RT failure.
bfisk is offline  
Old 12th Mar 2010, 01:20
  #7 (permalink)  
 
Join Date: Jan 2004
Location: Here and there
Posts: 3,104
Received 14 Likes on 11 Posts
Originally Posted by bfisk
Wrt that approach plate, take a look at the Dallas Forth-Worth 35R Cat III ILS approach: http://naco.faa.gov/d-tpp/1002/06039I35RC3.PDF
It's got no IAF!
What does the "(IF)" stand for at GALOP?
AerocatS2A is offline  
Old 12th Mar 2010, 01:45
  #8 (permalink)  
 
Join Date: Dec 2002
Location: Where the Quaboag River flows, USA
Age: 71
Posts: 3,415
Received 3 Likes on 3 Posts
"IF" is an initial fix, direct to which ATC can send a RNAV-equipped aircraft. Said aircraft can then intercept and fly the ILS, but the intercept angle cannot exceed 90 degrees.

If you are non-radar or NORDO, you have no other choice but to proceed from the enroute structure at a fix on the procedure to an IAF, and fly the entire procedure from the IAF, including any course reversals. Radar vectors are intended to put the aircraft on an INTERMEDIATE segment at an altitude compatible with the "platform" altitude i.e. a descent gradient of about 200 ft/nm. The intermediate segment begins with the course reversal. It has a low descent gradient due to the fact it is here the pilot is supposed to be slowing and configuring. The final segment begins at the FAF or FAP.

These "RADAR REQUIRED" approaches, as at DFW, have been controversial in the TERPS community as lacking a defined intermediate segment, prior to the appearance of an "IF" and RNAV. So, technically, when radar vectored, the pilot is vectored to a segment that does not exist.

GF
galaxy flyer is online now  
Old 12th Mar 2010, 11:39
  #9 (permalink)  
 
Join Date: Jun 2006
Location: Europe
Posts: 716
Likes: 0
Received 0 Likes on 0 Posts
According to the legend of the digital Terminal Procedures Publication, pg 7, IF means Intermediate Fix, while initial approach fix is termed IAF.
bfisk is offline  
Old 12th Mar 2010, 12:29
  #10 (permalink)  
 
Join Date: Jan 2004
Location: Here and there
Posts: 3,104
Received 14 Likes on 11 Posts
Thanks, I thought it must be one of those two.
AerocatS2A is offline  
Old 12th Mar 2010, 12:30
  #11 (permalink)  
Thread Starter
 
Join Date: Apr 2008
Location: India
Posts: 8
Likes: 0
Received 0 Likes on 0 Posts
Thanks Y'all!

Thanks for all your answers, but then again, thats a CAT III plate, and if you go lost comms, you're not legal to shoot the cat 3 approach, in which case the lack of an IAF doesnt matter anymore.Right? It also says radar required, so that you can get vectored for the intercept, so if you're lost comms, then you cant hear them vector you(assuming receiver failure....). I agree that radar can be used in lieu of a published IAF, but if the field goes non radar then you cant fly that approach for lack of an IAF. ANyways, check pilots pi$$ me off sometimes! I asked him these questions, and he asked me if I was testing him!

Floyd,
F/O 737-800/900 India
FlyBoyFloyd is offline  
Old 12th Mar 2010, 16:39
  #12 (permalink)  
 
Join Date: Dec 2002
Location: Where the Quaboag River flows, USA
Age: 71
Posts: 3,415
Received 3 Likes on 3 Posts
bfisk

I stand corrected. Thanks for the link.

GF
galaxy flyer is online now  
Old 12th Mar 2010, 16:59
  #13 (permalink)  
 
Join Date: Jul 2006
Location: USA
Age: 41
Posts: 111
Likes: 0
Received 0 Likes on 0 Posts
The truth is that both of you are right. It's just a typical "check airmen" debatable topic because they have nothing better to do. There are no winners to this argument and let me explain why.

Suppose you go to an airport that has an obstacle departure procedure. Suppose you takeoff from runway 5 and it says in the OBS DP to not make any turns before 1000'AGL. Then when you line up and get issued takeoff clearance, the controller tells you to be at heading 035 at the runway departure end. What do you do?

The book answer to that, is, you comply with the takeoff clearance. Reason is, that the obstacle DP is available when there is no one to take responsibility (or as we like to call it in our law suit loving country - liability). If there is no tower (i.e closed), if there is no radar and your are in IMC then the OBS DP would apply.

Going back to your question. The answer to the check airmen is trifold. The initial approach fix is a good aid, just like everything in the IFR system is an AID. An aid to achieve the purpose of not hitting anything while being IMC. If you can come up with a combination of alternate means of avoiding terrain/obstructions be it, using grid MORAs and somekind of a race track pattern over the outer marker to lose altitude or anything of any sort you are golden. When you are lost comm, you are technically an emergency airplane. You might not call it that way, but the controller is giving you priority whether you like it or not. In lost comm you will do everything possible to the extent needed to meet the emergency and get out of it alive.

You want to use IAF, use it. Your check airmen doesn't want to use it? Don't use it. Its irrelevant. It's a total class room debate that really does not apply in reality.

If you flew a limited cessna 172 and couldn't reach grid MORAs and only had low airways and feeder routes to IAFs available to you, then that's one thing. If you have a jet capable of climbing to FL410 and come down in an instant, it's entirely up to you which set of rules you want to follow in order to maintain clearance and stay alive.

Two words. STAY ALIVE. That's the whole theory of IFR. That's as simple as you can make it.

Don't hit mountains, don't hit buildings, don't hit other airplanes. If you can reuse your own airplane afterwards it's a bonus.
downwindabeam is offline  
Old 12th Mar 2010, 17:05
  #14 (permalink)  
 
Join Date: Jul 2006
Location: USA
Age: 41
Posts: 111
Likes: 0
Received 0 Likes on 0 Posts
In answer to your second question of where do you commence an approach from, going with my theory of getting out of it alive.

Again... same principle. You can be creative. You are an emergency airplane and you will do what's needed.

You can descend to the grid MORA and then use a racetrack pattern over the OM if one is prescribed.

You can descend to MSA and then use a long final in order to have a chance to get down to profile altitudes.

You can decent to MVA altitude should you happen to know it and join the approach.

You can go to an airport that is VFR and land visually and say screw it. [if you happen to see where the cloud deck ends from where you are at]
downwindabeam is offline  
Old 12th Mar 2010, 22:12
  #15 (permalink)  
 
Join Date: Dec 2002
Location: Where the Quaboag River flows, USA
Age: 71
Posts: 3,415
Received 3 Likes on 3 Posts
Downwindabeam

You are very nearly dangerously wrong in much of your advice, it is not a "class room" debate, but basic IFR theory. If not in radar control, you have ONLY ONE means of not hitting the ground--"black line IFR", that is strict adherence to the lines and altitudes on the FAR 97 or PANS-OPS Instrument Approach Procedure. No exceptions. FAR 97 makes the published IAP, a FAA regulation.

First, the Aeronautical Information Manual (US) in Chapter 5 and TERPS states that the approach begins at, surprise, the Initial Approach Fix. The only exception is when being radar vectored to the final approach course, where technically the controller "short cuts" the plane onto the intermediate segment and the pilot takes over navigation. All approaches, even the latest SAAAR RNP ones, begin at an IAF(s).

You cannot be creative, just because you have an emergency. Here are problems with your last post:

--Grid MORAs, while charted for obstacles, do NOT guarantee communication (if radios operative) or navigation signal coverage. They are not meant for navigation, they are solely for terrain reference.

--MSAs are for emergency use only and again do not guarantee signal coverage, sorry about not finding that OM.

--MVAs are for the controller's use ONLY, according to the AIM and FAAO 7110.65. MVAs are not a TERPS'd product, they are generated at each FAA facility and cannot be used for pilot navigation. Plus, in the cockpit, there is no valid way to confirm your position relative to the MVA sectors. Your map does not have an MVA overlay, so how do you propose to orient yourself to the MVA chart?

The ONLY safe answer to the OP's question is strict adherence to the charts and stay on the black lines. Your idea that a pilot in an emergency can "make up" a route and altitude profile is simply not correct and dangerous.

The check airman's point was that IAFs are there, but when radar vectored one will not pass over the IAF, but intercept the course from a vector.

Lastly, the tower controller's "instruction" to fly heading of 035 is not a clearance, it is an instruction. If an runway heading is required to ensure obstacle clearance, it should be flown until assured of terrain clearance. As you are not in "radar contact" that heading guarantees nothing as to the terrain.

You might get away with some of those ideas in Florida or Kansas, in much of the world, not hitting anything would be mostly due to luck.

BTW, I have been in India and flying around, "making it" would make you a statistic quickly. Tirupati would be one place.

GF

-------------------edit to add from FAA Instrument Flying Manual---------------

An IAP can be flown in one of two ways: as a full approach or with the assistance of radar vectors. When the IAP is flown as a full approach, pilots conduct their own navigation using the routes and altitudes depicted on the instrument approach chart. A full approach allows the pilot to transition from the en route phase, to the instrument approach, and then to a landing with minimal assistance from ATC. This type of procedure may be requested by the pilot but is most often used in areas without radar coverage. A full approach also provides the pilot with a means of completing an instrument approach in the event of a communications failure.

--------------------edit to add from FAAO 7110.65 ATC Handbook-----------

Standard Instrument Approach Procedures shall commence at an Initial Approach Fix or an Intermediate Approach Fix if there is not an Initial Approach Fix.

Last edited by galaxy flyer; 13th Mar 2010 at 02:43.
galaxy flyer is online now  
Old 13th Mar 2010, 15:25
  #16 (permalink)  
 
Join Date: Aug 2008
Location: North America
Age: 64
Posts: 364
Likes: 0
Received 0 Likes on 0 Posts
Absolutes

The DFW 35R Cat III ILS example interested me. I do not have access to my charts at the moment. But I would reason that the Cat III Chart shares most items in common to the CAT I chart for the same runway, and I would “guess” the CAT I approach plate for DFW 35R would have an IAP (or several) published. Therefore IAP fixes are published for that runway using that localizer.

I would say FlyBoyFloyd you are right; I like your logical explanation.

Several others answered the vectored for the approach situation well; you are being let to the intermediate portion by ATC.

The older I get the fewer absolute statements I make; for example “Every approach must have an IAP published” or “All published approaches have an IAP”.

I would not call you a first officer monkey. I have been in the right seat; now that I am in the left seat let me make an absolute statement. I don’t have all the answers. And you know that the people sitting next to you do not have all the answers all the time either. Being an instructor at the airline level is a license to learn (been there done that).
Northbeach is offline  
Old 13th Mar 2010, 20:09
  #17 (permalink)  
 
Join Date: Jun 2005
Location: London
Posts: 390
Likes: 0
Received 0 Likes on 0 Posts
The older I get the fewer absolute statements I make
Best post I've seen in a while

P
Permafrost_ATPL is offline  
Old 14th Mar 2010, 00:56
  #18 (permalink)  
 
Join Date: Jul 2006
Location: USA
Age: 41
Posts: 111
Likes: 0
Received 0 Likes on 0 Posts
Galaxy_flyer:

Have you noticed the running theme of what you wrote? Signal coverage, radio coverage...

We were talking emergency. And the running theme of my post was DONT HIT TERRAIN by ALL mean available to you.

Enlighten me then. How does one get to the IAF when there is no feeder route or the IAF is not part of the low altitude system?

Yes you can take India and anywhere else in the world that has terrain as examples, but the truth is, those places adhere to the rules much better than we do in the states. The truth is, in the US, some approaches have fixes one would have a good amount of trouble navigation to using what you call "black lines" cause sometimes those black lines don't exist.

MSA Is indeed used for emergency and when you are lost comm, you are essentially just that.

You can keep on believing there is only one way and one way only to fly an airplane, I chose to open my mind and think of all possible alternatives to avoid terrain and obstacles and get on the ground safely.
downwindabeam is offline  
Old 14th Mar 2010, 01:40
  #19 (permalink)  
 
Join Date: Dec 2002
Location: Where the Quaboag River flows, USA
Age: 71
Posts: 3,415
Received 3 Likes on 3 Posts
FlyBoyFloyd

Your position is quite correct, best of luck in your flying, be safe

Downwindabeam

I suggest you read TERPS and the FAA Instrument Procedures Manual, post haste And, you might read the FAA General Counsel's opinion on whether an SIAP begins at the IAF. Here's the link to the FAA GC TERPS opinion.

Here is one gem in the IPH,

In the absence of radar vectors, an instrument approach begins at an IAF.
As already shown, there are FAA TERPS approaches that do NOT have "black lines" from the enroute structure to an IAF or IF, they are also clearly marked "RADAR REQUIRED". In your example of a radio out emergency, those approaches are NOT authorized. It is a TERPS requirement that an airport will have approaches that provide a means from the enroute structure, thru the approach, missed approach and back to the enroute structure. Yes, there probably are exceptions, but the idea that a pilot, non-radar by virtue of radio failure, is prudent in being creative has no place in an airplane. The procedures are carefully drawn, I have been involved in doing so, to provide for this emergency case. Following the black lines on the chart are 99.999% of the time better than being "creative".

FAR 97 makes a SIAP a matter of regulation and violating any part of a approach procedure a FAR violation. FAR 91.185(3 iii) Loss of Two-Way Communication directs the pilot to...Proceed to a fix from which the approach begins..." Combined with the AGC opinion, makes it clear that radio out, an FAR 97 procedure must be flown as published.

Please read FAR 91.175 (i) on operating off published routes and FAR 91.177 on minimum IFR altitudes. These rules apply with or without radios or ATC. Here is a resource of good information from a respected airline captain and TERPS expert:

IFR Refresher Magazine (TERPs) Many good articles on IFR flight.

I am sorry to be so "hot" about this subject, but your advice is not appropriate and, in the wrong hands, dangerous.

Lastly, how many thousands of hours flying around the world do you have and how many schools in instrument flying have you attended that make you better qualified than the professionals that design approach procedures?

The running theme in all IFR flight is "not hitting the terrain"and following the "black lines" on the chart are the best, perhaps only, way to do so. No one on the lines, at or above the altitudes, has hit terra firma.

GF

Last edited by galaxy flyer; 14th Mar 2010 at 05:00.
galaxy flyer is online now  
Old 14th Mar 2010, 10:48
  #20 (permalink)  
 
Join Date: Aug 1998
Location: Ex-pat Aussie in the UK
Posts: 5,810
Received 134 Likes on 66 Posts
But then what if you have a comm failure in IMC, while enroute to a major airport? Assuming you remain in IMC all the way, then you have no choice but to continue to the intended destination, and get yourself onto an approach any way can, depending on your navigational capabilities. ATC will shut down the entire airspace for you, since they won't know which approach to which runway you are planning. Therefore, I expect they want you to just get onto the ground ASAP, by any available means, without worrying about trivial details such as IAFs. If you have GPS, proceed direct the OM. If not, use the LOC DME to arc to the OM.
In Europe, at least, the expected no-radio approach procedures are either specified for each airport (our in-flight reference being the EMERG section of the Jeppesen En-route folder), or are should be the generic "proceed to the IAF for the expected approach".
Checkboard is offline  


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.