Posts Tagged ‘Instrument’

Instrument Changes: Approaches without IAFs and Vectors to Fixes

Monday, March 24th, 2014

 

00285R11

My article about a “new” third way to start an approach, by flying to the intermediate fix (IF), drew many comments, including one asking “wouldn’t it be best to establish yourself earlier on the approach earli
er than the IF.” Another flight instructor explained that, in the case of the GPS 31 approach into Palo Alto, the IAF locations are inconvenient (unless you’re flying in from Japan!) and are over mountainous terrain, which is why most pilots start this approach at the IF. Now, even the FAA doesn’t consider an IAF a necessity and many approaches are charted without any IAFs!

First, my thanks to longtime friend Hilton Goldstein, for pointing out a number of approaches that lack an IAF. Hilton is the brains behind WingX, an integrated aviation app for the iPhone and iPad that provides just about every function a pilot might need for planning and flying a flight. He reviews every new instrument procedure chart before it goes into WingX, which is how he spots interesting procedures.

But first let’s go to the source, the Air Traffic Control Handbook, Order 7110.65U. Last year, section 4-8-1 Approach Clearance, was updated and now says in part:

“Standard instrument approach procedures (SIAP) must begin at an initial approach fix (IAF) or an intermediate fix (IF) if there is not an IAF.” [emphasis added].

Newark Liberty International (KEWR) is a great example. By my count, they have a total of 14 approaches that lack an IAF; all begin at an IF. An example is the RNAV (GPS) RWY 11 approach, which starts at the IF, MUFIE. Note the chart is marked RADAR REQUIRED, as are all charts for procedures starting at an IF.

Looking for the RADAR note is one possible clue that an approach might lack an IAF and start at an IF. At KEWR, 14 approaches have that restriction and all start at an IF. Well technically, one of them doesn’t have an IF, but it was probably an oversight.

If you look at the VOR RWY 11 at KEWR, you’ll note it starts at PINEZ. The next fix, LOCKI, can be identified as the Final Approach Fix (FAF) since it shows a Maltese cross at LOCKI in the profile view. An intermediate segment begins at an IF and terminates at an FAF, in this case LOCKI. Thus PINEZ should be an IF, though it’s unmarked. So technically, the FAA cannot clear an aircraft to start this approach at PINEZ, since per JO 7110.65U, an approach must begin at “an intermediate fix (IF) if there is not an IAF.” My guess is “IF” will be added to PINEZ in a future chart revision.

Why don’t these approaches have an IAF? Probably because it simplifies things in what’s already some of the most congested airspace in the United States. Besides, per the FAA Instrument Procedures Handbook, “The purpose of the initial approach segment is to provide a method for aligning the aircraft with the intermediate or final approach segment.”

In most cases, an aircraft can start at an IAF from any direction. Depending upon the angle of arrival at an IAF, an aircraft may need a lot of space and time to get turned around and straightened out, hence the need for the initial segment.

But airliners flying into a major metropolitan airport like Newark are usually vectored in an orderly line more than 100 miles out from the start of an approach. Thus they’re well lined up and hairpin turns aren’t required as they start an approach. In that kind of structured environment, there’s no need for an initial segment to get lined up and hence no reason not to start at an IF. So what do you think? Will the IAF slowly fade away in the future, except in non-radar environments?

Vectors to Fixes Outside the FAF
Another change last year in section 4-8-1 of 7110.65U says that aircraft can now be vectored to start an approach at any fix, as long as it’s 3 NM or more outside of the FAF. Typically in the past, vectors have been to join the final approach course along a leg, not to a particular fix (except for the IAF and IF). Here’s the exact text:

“Where adequate radar coverage exists, radar facilities may vector aircraft to the final approach course, or clear an aircraft to any fix 3 NM or more prior to the FAF along the final approach course in accordance with Paragraph 5-9-1, Vectors to Final Approach Course, and Paragraph 5-9-2, Final Approach Course Interception.”

Looking at Paragraph 5-9-2, one finds that controllers must assign a heading that cannot exceed 30° from the final approach course. Thus we end up with the following maximum intercept angles for joining the final approach course at a fix:

  • 30° when at fixes outside the FAF, except for:
  • 90 ° for intercepts at the IF, and
  • any angle for intercepts at an IAF.

I’d venture to say that the majority of approaches don’t have any other fixes outside the FAF, other than the IF and IAF, which were covered by prior rules. Yes, you’ll find lots of feeder fixes outside the IAF, but you can typically join these at any angle. So while this rule change may give pilots and controllers another option on some approaches, it’s not clear to me that it offers much new benefit. If you’re aware of an approach where having this option offers a significant operational advantage, please share it with readers in the comments.

One thing we know for sure that’s constant is change. And that the rate of change is accelerating. Which means pilots and controllers alike will need to spend even more time learning about future changes and how they affect they way we fly. Perhaps that’s why a pilot certificate is often called a license to learn.

How to Request to Start an Approach at the Intermediate Fix (IF)

Tuesday, February 25th, 2014
Requesting to be cleared "Direct to" the IF can result in a hairpin turn that's not permitted by the AIM.

Requesting to be cleared “Direct to” the IF can result in a hairpin turn that’s not permitted by the AIM.

Instrument pilots know that there are two ways to start an instrument approach: they can get vectors or fly direct to an initial approach fix (IAF). Last month, I wrote about the “new” third way to start an approach, by flying to the intermediate fix (IF). This month I planned to write about the challenges in requesting to start an approach at an IF. Coincidentally, the day this article was due, the problem I planned to describe occurred…again.

I added quotes to “new” because, while this third method has been described in section 5-4-7(i) of the Aeronautical Information Manual (AIM) since 2006, I expect it will take many years before this information fully permeates the pilot and controller populations. Why so long? Partly because old habits in aviation die slowly and because standard IFR phraseology is confusing when applied to starting at an IF.

The confusion is not unlike the language issues that led to “Position and hold” being changed to “Line up and wait,” a change I enthusiastically supported. Countless times I’ve been in the cockpit with a pilot who confused “Position and hold” with “Hold short,” presumably because they both contained the word “hold.” In this case, potential confusion exists with the words “vectors” and “direct to,” when used to request to start an approach at an IF.

In September 2012, I exchanged several emails about this problem with a friend who is a supervisor at the Northern California TRACON. In my first email, I wrote in part,

“In my books, I tell pilots that there are three ways to fly an instrument approach:
1. vectors,
2. own navigation (or pilot navigation) to an IAF, and
3. a third method, which appeared in the Aeronautical Information Manual beginning in 2006 that allows pilots to start at an IF under certain circumstances (see extract from my G1000 Book below).

“We have short, well understood names that pilots use to ask controllers for the first two methods. But I’m not aware of a convenient name for pilots to use when requesting this third method. Are there quick, easy names that controllers use to describe this third method? Or should we be inventing a new name for it and promoting it among the aviation community?”

Why the need for a “quick, easy name?” Because for years, I’d sometimes had to clarify my request to start at an IF by adding that I’d like “to be vectored to a point from which you can clear me direct to DOCAL with a turn of less than 90 degrees.” That’s a mouthful and an inefficient use of radio time at a busy TRACON.

The reply from my supervisor friend was that the consensus at the facility was that a pilot should name the approach and ask to start at the name of the IF. In the case of the GPS 31 approach at Palo Alto, a pilot would ask to “start the approach at DOCAL,” Alternatively, you might consider requesting “to start the approach at the Intermediate Fix,” which should trigger the controller to remember the 90 degree turn rule.

Potential Confusion in Phraseology
Using the words “vectors” or “direct to,” works great when a pilot is requesting to start an approach with vectors or at an IAF. But they can be confusing when used to start an approach at an IF.

“Vectors” means you’ll be guided to join an approach at least several miles outside of the final approach fix (FAF). Requesting “vectors to DOCAL” could make sense, except that the JO 7110.65U tells controllers that when giving vectors, they are to turn pilots to within 30 degrees of the final approach course, not the 90 degrees permitted at an IF. So you don’t really want “vectors” to the IF.

If instead of asking to “start the approach at DOCAL” a pilot asks to be cleared “Direct to DOCAL,” controllers will sometimes take that literally and clear a pilot from their present position to the IF. But this can result in nearly a 180 degree turn at the IF, which isn’t permitted under 5-4-7. And that’s exactly what happened to me today. I had just crossed over Moffett Field and was essentially on a downwind leg to the approach. The controller asked whether we wanted vectors or to start the approach at DOCAL. I chose the latter and was immediately cleared “Direct to DOCAL.”

I’m not sure why the controller did that, though I’m guessing he was familiar with the 90 degree rule in 5-4-7. Shortly afterwards, I said “we’d like to continue on this heading until we can make a turn of less than 90 degrees at DOCAL,” to which he said “That will be fine.”

Why so casual? We weren’t IFR, but were doing a VFR practice approach, where separation standards are relaxed. Under those circumstances, I’ve seen controllers not require a turn of less than 90 degrees at an IF, a practice that may confuse pilots and controllers alike about the proper way to start an approach at an IF.

Get on the Same Page as the Controller
Regardless of how you request an approach, or how you are cleared to an approach, it’s important to be on the same page as the controller. If you have any doubt as to whether the controller and you have the same game plan in mind, request clarification. In the meantime, don’t hesitate to ask to “start the approach at the IF” if that’s how you would like to fly the approach.

Three Ways to Start an Instrument Approach: Vectors, IAF and Intermediate Fix (IF)

Tuesday, January 28th, 2014

KPAO GPS 31

A friend lamented on Facebook that the NDB procedure at the airport where he learned to fly is no longer available. He added  “For some reason it makes me a little sad.” I’m guessing his sadness had more to do with his feelings about learning to fly at that airport, than it did about flying an NDB approach. Or perhaps he was reminiscing about the pride he felt in mastering the NDB approach.

I used to enjoy the intellectual challenge of flying an NDB approach and the even greater challenge of teaching others to master it. But no more. There are no NDB approaches left in the S.F. Bay area where I teach and I say “good riddance.”

The approaches were inaccurate and difficult to fly and former Secretary of Commerce Ron Brown was killed when U.S. Air Force pilots failed to correctly fly a rare “dual NDB” approach. I’m much prefer to see pilots expend their intellectual horsepower on mastering flying IFR approaches with modern GPS receivers, which can be more work than learning NDB approaches, and staying up to date on rule changes.

One rule change that frequently causes confusion among pilots and controllers alike relates to the third way to fly an instrument approach. All instrument pilots know you can fly an approach with vectors or use pilot navigation to start at an IAF (initial approach fix). However there’s a third way that’s been around since 2006, but word about it has been slow to get out to pilots and even to a few controllers.

Pilots can now start an instrument approach, with some restrictions, by flying directly to the IF (intermediate fix). Just to remind those who may have forgotten, the initial segment of a typical instrument approach procedure starts at an IAF and ends at the IF. So typically the IF is the next fix after the IAF as you fly toward the airport.

You might be wondering, “What’s the big deal, why would I want to skip the IAF.” For many approaches it won’t matter, especially if the IAF is along your direction of travel toward the airport. But for some approaches it can save a few clicks on the Hobbs meter. For example, at my home airport of Palo Alto, Calif., the GPS 31 approach has two IAFs, but both are in the boonies and most pilots start the approach at DOCAL, the IF.

You’ll find the details about starting an approach at an IF in section 5-4-7(i) of the Aeronautical Information Manual (AIM), where it first appeared in 2006 (yes eight years ago!). However, you won’t read about it in the FAA’s Instrument Flying Handbook or even in the FAA Instrument Procedures Handbook, both of which are excellent publications.

The rule applies to all approach types, not just RNAV (GPS) approaches. Here’s the current text from the AIM:

ATC may clear aircraft that have filed an Advanced RNAV equipment suffix to the intermediate fix when clearing aircraft for an instrument approach procedure. ATC will take the following actions when clearing Advanced RNAV aircraft to the intermediate fix:

1. Provide radar monitoring to the intermediate fix.

2. Advise the pilot to expect clearance direct to the intermediate fix at least 5 miles from the fix.

NOTE - This is to allow the pilot to program the RNAV equipment to allow the aircraft to fly to the intermediate fix when cleared by ATC.

3. Assign an altitude to maintain until the intermediate fix.

4. Ensure the aircraft is on a course that will intercept the intermediate segment at an angle not greater than 90 degrees and is at an altitude that will permit normal descent from the intermediate fix to the final approach fix.

Here’s what it means to a typical GA pilot.

1) You need to be GPS equipped (which is the only practical way for most GA aircraft to be RNAV equipped). This let’s you find your way independently to the IF.

2) The controller might advise you that you’ll be starting the approach at the IF, but more typically, you’ll have already requested that of the controller.

3) You’ll be assigned an altitude to maintain until reaching the IF. Most likely you won’t be on a published segment of the approach until the IF, so you need to be assigned a safe altitude.

4) The controller cannot clear you directly to the IF until you’re in a position from which you can make a turn of less than 90 degrees to join the approach at the IF.

It’s the last part, making a turn of less than 90 degrees, where pilot and controller sometimes get confused. The idea is that the turn at the IF needs to be an easy one, much like turning left or right at the intersection of two streets. It can’t be a hairpin turn or resemble something like a U-Turn.

Think of it this way. If you were to draw a line on your chart at the IF that’s perpendicular to the intermediate segment, on one side of the line, the side farthest from the airport, you are allowed to fly directly to the IF, since the turn inbound is less than 90 degrees. If you’re on the other side of the line, the side closer to the airport, you can’t be cleared to the IF until after you’ve been vectored across the perpendicular line.

All of this presents some new challenges for pilots and controllers, especially if they’re unclear on the rule. We’ll talk more about those challenges….next month.