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Uneven STARs

I’m often surprised at the widely varying quality of domestic Standard Terminal Arrival procedures. The name makes for a good acronym (“STAR”), but from an aviator’s perspective there’s precious little about them that is standard. Some are simple and pilot friendly, whereas others can be downright awful.

There are reasons why each STAR is set up the way it is. These procedures must interface with both the en route structure (aka airways) and the terminal environment while respecting terrain, airspace, and other such limitations. And you’d think between satellite navigation and modern avionics, it would be possible to fly just about anything with ease.

If only.

Bizjet pilots who fly into the NYC area will recognize this STAR. Whether they like it, however, is another story altogether…

Anyone who flies a business jet is undoubtedly familiar with the WILKES-BARRE FOUR arrival. Most of us who utilize this procedure are headed into Teterboro (KTEB), but it also serves a number of other greater New York area general aviation airports, including Morristown, Linden, Princeton, Somerset, and Solberg.

To me, the WILKES-BARRE FOUR has always been the penultimate example of a poorly designed STAR. It’s almost as if whoever conceived this procedure was unaware of (or chose to ignore) the realities of operating a high-performance turbojet.

The procedure has arriving aircraft flying east, and in this part of the country tailwinds are often quite high at altitude. In fact, they often increase rather than decrease as we descend. I’ve seen more than 150 knots on the tail while being sent direct to HOXIE, STENT, or the Wilkes-Barre VOR.

You can probably already see the first problem: My 460 knot true airspeed has combined with the tailwind to give me a ground speed of more than 600 knots. That’s nearly 700 mph. Slick airplanes don’t want to “go down and slow down” at the same time, and there’s precious little drag on a Gulfstream.

Not only is the procedure itself a problem, but the way it’s used by ATC amplifies the difficulty. Due to the quantity of arrivals into Newark, JFK, and La Guardia, we’re almost never allowed to fly anything like an optimized descent profile. Instead we’re given descent clearance either very early or very late.

If it’s early, no problem. I can fly that, although it’s very inefficient to be at low altitude so far from the airport. (Side note: I was returning to New York from Sao Paulo very early one morning and ATC had us descend to 3,000 feet msl. When we leveled, off, I looked at the FMS and noted that we were still nearly 300 nm from Teterboro. We were out of sight of land, and I was only half-joking when I told the controller, “I’m not sure who we offended, but I apologize.”)

You’d think the heavy traffic and high tailwinds would call for the WILKES-BARRE FOUR to be one of the more precisely designed and utilized STARs in existence, but it seems to be the exact opposite. Instead, we’ll sometimes be held high until well past a normal top-of-descent point and then instructed to cross MUGZY at 6,000 feet. There have been plenty of occasions when even with the power at idle and the speed brakes deployed for the entire seven mile vertical descent from cruise altitude, I still cannot make the 6,000 foot restriction because we’ve got to slow to 250 knots prior to descending through 10,000 feet.

While I understand the challenges controllers, airspace designers, and traffic managers are dealing with, there are limits to what an aircraft can physically accomplish, and this arrival procedure often pushes those boundaries on a regular basis. I’ve had to use the words “unable” more often on the WILKES-BARRE arrival than any other procedure I can think of.

The polar opposite of the WILKES-BARRE are procedures like the PUFFER FOUR arrival into Denver. This STAR has a variety of measured step downs, and it slows the aircraft to the 250 knot speed limit before pushing through the 10,000-foot barrier. If anything, it slows the aircraft a bit too early, although with the turbulence generated by the Rockies, it’s often a welcome restriction which feels tailor-made to the prevalent conditions for that area. I’d also note that this procedure allows for both north and south arrivals.

Some STARs are just a mystery. Not so much in how they look on paper, but in how they’re used in real life. As evidence, allow me to present the LYNXX EIGHT arrival procedure into Van Nuys. VNY is the west coast equivalent of Teterboro—the corporate jet and charter hub for the greater Los Angeles area.

I’ve flown this procedure a hundred times, and not once have I ever flow it as charted or been cleared to “descend via.” Even at 2 a.m., the controller will still given direct-to various waypoints and verbally provide each altitude change, often in 1,000-foot increments. I’m sure there’s a reason for it—probably north and south crossing traffic between the high desert and Los Angeles basin—but if this is to be the case, why bother designing or assigning this STAR at all?

I doubt the issue can be blamed entirely on crowded metropolitan areas with demanding layers of airspace, because one of my favorite arrivals is the DSNEE THREE arrival into my home field, John Wayne Airport in Orange County, California. I’ve almost always been cleared to descend via, and the arrival navigates the high terrain around Palm Springs as well as the crowded LAX arrival corridor and other SoCal airspace with both elegance and ease, providing a beautiful transition into what’s usually a visual approach for Runway 20R.

I always end up wondering why more STARs can’t be like that, both in how they’re designed and used by air traffic control. If a STAR is awkward and inefficient for the pilot, it’s probably no prize for the guy on the other side of the radio either.

If there’s one thing I’ve learned, it’s that STARs are like Forrest Gump’s box of chocolates: You just never know what you’re going to get.

Ron Rapp is a Southern California-based charter pilot, aerobatic CFI, and aircraft owner whose 9,000+ hours have encompassed everything from homebuilts to business jets. He’s written mile-long messages in the air as a Skytyper, crop-dusted with ex-military King Airs, flown across oceans in a Gulfstream IV, and tumbled through the air in his Pitts S-2B. Visit Ron’s website.

FAA plans to decommission NDB’s at Glenallen, Mekoryuk and Noatak: User feedback requested

The FAA has issued Letters to Airmen outlining plans to decommission the Nondirectional Beacons (NDBs) at the Gulkana (GKN), Mekoryuk (MYU) and Noatak (WTK) airports.  In all three cases, the decommissioning’s are for navaids that have failed, and have been out of service for some time.  Even though they are non-functional, they serve as fixes that are part of the airway structure, or are components of instrument approaches.   If the removal of these navaids impacts your operation, please let the FAA know, using the contact information provided below.

Moving to Space Based IFR Infrastructure
While the FAA is moving to a space-based IFR system, NDBs in some locations are still serving not only as the basis for instrument approach procedures, but as anchor fixes for IFR airways.  Last year AOPA was part of an industry group that looked at the IFR Enroute infrastructure in Alaska.  Working with the Alaska Air Carriers Association, Alaska Airmen Association, National Business Aviation Association and other organizations, the group delivered formal recommendations to the FAA. The topics covered in the report were wide ranging including sections acknowledging the role NDBs play in the enroute environment, and expressed concern that some GPS based T-Routes have a much higher Minimum Enroute Altitude than the NDB-based colored airways. One of the recommendations called for the FAA to consider operator impacts before decommissioning any airway supported by NDBs.  Responding to a Letter to Airmen is one mechanism that the FAA uses to collect user feedback.

 

This specific working group was only tasked to look at the enroute infrastructure, but acknowledged that NDBs in some locations still serve an operational role in the terminal environment, which should also be considered before these stations are decommissioned.

User input needed
The FAA is struggling to move into the space-based, NextGen era, balancing the need to keep existing “legacy” systems in place, while obtaining funding to stand up new infrastructure.  AOPA and others are pushing FAA to expand the network of ADS-B ground stations in Alaska, to provide a “minimum operational network” across the state.  Decommissioning legacy navigation aids is one way to free up resources, but only after the operational needs of the users have been considered.  FAA is asking for our feedback on these three stations. If you fly to these areas, let the FAA know if removing these NDBs impacts your operations.  Please contact:

Mark Payne, NISC III contract support
Operations Support Group
Western Service Center

Phone:  425-203-4515

Email:    [email protected]

Please send copies to AOPA at: [email protected]

Links to the FAA Letters to Airmen:

Glenallen NDB OSGW-36 (003)

NANWAK NDB_DME OSGW-35 (003)

Noatak NDB Decommissioning OSGW-33

Follow-on Survey for Alaska IFR users

If you fly IFR below 18,000 feet in Alaska, AOPA and the Alaska Airmens Association need to hear from you—again.  In July, an online survey was conducted to query IFR pilots about the Alaskan low-altitude enroute structure.  The results of that survey helped us learn some of the details about how we navigate the enroute structure.  While GPS is the most predominant navigation tool, about 20% of the time VOR’s are still used to fly Victor routes. It also revealed that obtaining low Minimum Enroute Altitudes (MEAs) to stay out of ice is a major desire to successfully use the IFR system.  This and other information from the survey was used to start a discussion with FAA about the possible evolution of the Alaska enroute IFR structure.  An industry lead group met with FAA in August to consider what changes might be made in Alaska to support the migration to NextGen, while not losing important qualities of the current system.

Alaska has several pockets of Class G “brown” airspace, above 1,200 ft agl. Pilots flying IFR in this airspace do not receive aircraft separation services.  An IFR pilot survey is looking for feedback from pilots regarding this type of airspace.

Alaska has several pockets of Class G “brown” airspace, above 1,200 ft agl. Pilots flying IFR in this airspace do not receive aircraft separation services. An IFR pilot survey is looking for feedback from pilots regarding this type of airspace.

More information needed
AOPA, working with the Alaska Airmens Association, is launching a second survey to obtain more information that will help inform the group concerning general aviation needs regarding the enroute phase of IFR operations in Alaska.  Questions about how the aircraft you fly are equipped, if you fly IFR in “brown” (Class G) airspace, and if you have encountered problems communicating with ATC are among the topics covered.  Taking five minutes to answer these and other questions will help us advocate for changes to improve the IFR infrastructure in Alaska.  If you are an active IFR pilot, please click here, and take the survey today!

Alaska IFR Survey: What do we need?

The FAA is undertaking a modernization of the National Airspace System (NAS) , and is moving to a space-based system.  While we will have ground based navigation aids for the foreseeable future, GPS based navigation has clearly become the dominant technology, and is changing the nature of our IFR enroute navigation structure.  Plans are already underway to update the low and high altitude system in the lower 48 states, but as we all know, well—Alaska is different.

Alaska's low altitude enroute infrastructure is the topic of a survey for IFR pilots who fly there.

Alaska’s low altitude enroute infrastructure is the topic of a survey for IFR pilots who fly there.

Recognizing that we have strong reliance on aviation for basic transportation in the state, the FAA is taking Alaska’s specific needs into account by establishing an advisory group to consider the needs of Alaska’s low-altitude (below 18,000’) IFR enroute system.  To prepare for this undertaking, AOPA and the Alaska Airmen Association are partnering on a survey of IFR pilots who fly in Alaska.  The survey will help define how you use the low altitude enroute IFR system today, and what your needs are for the future.

This information will help us advocate for your needs as the FAA looks at options to make changes to the NAS in Alaska.  While this effort is focused only on Alaska, the results will be integrated into other efforts around the country as we move to a space-based system.

If you are an active IFR pilot, please take the few minutes to take this online survey.  Click here to take the survey now.

Cold Temperature Correction Procedures Meeting in Alaska

The FAA’s update to the list of cold temperature restricted airports has generated questions from Alaska pilots about the process. Initially raised at a meeting of the Interior Alaska Flight Instructors Association in Fairbanks, the FAA is sending an official to Alaska from Washington DC to explain and discuss the procedures. Kel Christianson, from Flight Standards Performance Based Flight Systems Branch (AFS-470), will meet with pilots on Wednesday, January 20 at 7 p.m. Mr. Christianson will cover the background on why and how cold temperature correction procedures have been instituted in the National Airspace System, and provide detailed examples on making altitude corrections to instrument approach procedures.

Cold Temperature Correction Procedures apply to nearly 100 airports in Alaska.

Cold Temperature Correction Procedures apply to nearly 100 airports in Alaska.

The Fairbanks based CFI association compiled specific questions from Alaska operators in advance and supplied them to the FAA. A question and answer session will follow the briefing. FAA Air Traffic Control staff will also be on hand to answer questions. The meeting is being sponsored by the FAA Safety Team, and will take place at the Fairbanks International Airport Operations Center, 5195 Brumbaugh Blvd, on the west side of the airport.

Since almost a hundred Alaska airports are on the list, and winter tends to be our dominant season, these procedures may have a major impact on those pilots who fly IFR. Consider taking advantage of this meeting to learn more about this topic.

Slinging IFR

Flying helicopters IFR with a sling load presents unique challenges, requiring specific skills of the pilot.  One must obviously be able to control the helicopter without any outside visual references. Less obvious, one must also be able to correctly interpret the instruments, which reflect both the behavior of the load and the orientation of the helicopter. A Class B external load (sling load) is one that is free of the earth’s surface and is attached to the helicopter by a synthetic or wire line. The pilot is “flying” both the helicopter and the load, which at times can seem to have a mind of its own.

Today slinging IFR is not a common practice, though there was a time on the North Slope of Alaska where it was employed regularly. I thought it might be interesting to look at this operation in some detail.

 

An AW139 lifts off for an external load training flight out of Deadhorse Alaska.  Photo by Dan Adams

An AW139 lifts off for an external load training flight out of Deadhorse Alaska. Photo by Dan Adams

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Controlling the sling load

Normally one can see the external load, and make the necessary corrections. Lateral swinging is more common than a fore-aft motion or a circular motion, so we will focus on that. A quick lateral cyclic input towards the load, just as it reaches its apex, moves the aircraft over the load neutralizing its motion. You are essentially moving the aircraft over the load after it has swung out to the side. This dampens the movement of the load and stabilizes it. However, when flying IFR the instruments must be used to indicate the loads’ position and movement. The best way to learn how the instruments reflect the movements of the load is during VFR flight, when the load and gauges can be seen together.

Flying IFR with a sling it is important not to make corrections reflecting the gauges as one normally would, but instead understand exactly what the load is doing beneath you. The attitude indicator reflects rhythmic changes in bank angle from the load tugging the helicopter laterally side to side, as does the ball in the inclinometer. The inclinometer is used to indicate when and how much lateral cyclic input is necessary for a correction, though there is a natural lag. The load will reach its apex prior to the inclinometer, and the pilot must compensate for this natural lag. When the ball starts to swing out of center to the right and is about half way from its apex, the load is almost at its apex to the left, the pilot then uses left lateral cyclic as a correction. The rhythmic oscillations in the attitude indicator and inclinometer reflect the movements of the load, and the average of these movements are the actual orientation of the aircraft.  The pilot learns to mentally average these oscillations in order to control the pitch, roll, and yaw of the aircraft itself.

“An ounce of prevention is worth a pound of cure”, so one learns to make flight control inputs very smoothly so as to not aggravate the load. Turns are initiated slowly, and half standard rate turns are sometimes prudent.

Determining cruise airspeed

Another consideration is determining the target airspeed at which to fly.  This must be greater than Vmini (minimum IFR speed) and less than the loads effective Vne. While the aircraft will have an external load airspeed limitation, this may not be possible if the load is unstable at a lower speed. Many loads cannot be flown at the external load Vne, and the effective Vne must be determined. As the pilot slowly accelerates during takeoff, the load is carefully watched prior to IMC to determine what airspeed above Vmini the load can be flown at. Once that airspeed is determined, it is maintained for the entire flight.

Should the load show signs of instability below Vmini or only slightly above so as to not provide a safe and adequate airspeed window, the takeoff is aborted while still VMC.

One should be sure of a load’s stability and capability at a safe airspeed prior to IMC, and one should only fly known loads in IFR or at night. A known load is one that is similar to one previously flown during the day. The load characteristics are predictable and stable.

Autopilots and external load operations

Autopilots and external loads don’t usually mix, and many Rotorcraft Flight Manuals prohibit autopilot coupling during external load operations. The autopilot can be too abrupt in pitch attitude and roll, particularly when initiating and terminating turns. A pilot can make changes with a more gentle touch; such as slowly entering a half-standard rate turn when necessary. The autopilot can be used for stability augmentation; it just shouldn’t be coupled to the flight director directly controlling the aircraft.

Horizontal and vertical situational awareness

Class B sling loads can be jettisoned, either intentionally or unintentionally. The hook release is typically electric and controlled by the pilot. Under normal operation the load is released once it has been placed gently on the ground; however, in the case of an emergency the pilot may opt to release it in flight. Due to the possibility of the load being released in flight, persons or property are never overflown. This requires horizontal situational awareness; easy enough VFR, but IFR is another matter. Fortunately, the North Slope of Alaska provides assurance due to its desolate nature.

Vertical situational awareness must also be considered, not just for the helicopter but also for the load hanging underneath. With the typical 25 to 50’ line, the altitude of the load isn’t a factor in cruise flight; however, during the instrument approach it must be considered.

The Instrument Approach

As much fun controlling the helicopter and load may be in IFR conditions, eventually we do need to land. For that we need to fly an instrument approach. Let’s stick with the North Slope of Alaska, using the Deadhorse (PASC) ILS 05 as an example, using a little simple math.

A load 5 feet high hanging on a 50 foot line would require a 55 foot adjustment factor to the decision altitude. For the Deadhorse ILS, this means increasing the decision altitude of 267 feet to 322 feet, and ALS conditional altitude of 167 feet to 222 feet. It would also be prudent to include this 55 foot altitude adjustment into your preflight IFR planning.

Final Thoughts

While flying slings IFR is no longer common, the training for IFR slings still occurs. Having the skill and confidence to be able to fly a sling IFR is vital should unforecasted adverse weather be encountered, not unheard of on the Alaskan North Slope where the weather can change quickly. Airports and options are few and far between north of the Brooks Range of Alaska. These skills also translate well and are employed for night sling operations, which are still done on a regular basis.

Markus Lavenson is currently flying for Era Helicopters as a captain in the Sikorsky S92 and Leonardo Helicopters AW139 in Alaska and the Gulf of Mexico in oil and gas support missions. His varied career began shortly after graduating from the University of California at Davis, and has included everything from flight instruction and powerline patrol to HEMS and external load operations. His more than 10,000 hours of flight time comes from more than a dozen different types of helicopters and airplanes. Holding an ATP helicopter and commercial multi-engine fixed-wing, he also is a flight instructor fixed-wing and instrument flight instructor helicopters. Lavenson enjoys the intricate work of helicopter instrument flying, whether it’s to an airport on Alaska’s North Slope or one he creates to an oil rig hundreds of miles offshore.

FAA plans to eliminate instrument approaches in Alaska

As part of a national Notice of Proposed Rulemaking (NPRM), FAA has announced it plans to eliminate “redundant or underutilized” VOR and NDB approaches. Reported in an AOPA news story, the proposal is linked to the national effort to define a VOR Minimum Operational Network, also known as the VOR MON. As WAAS approaches and GPS based T-Routes become the basis of NextGen, the idea is to keep a VOR network as a back-up. In the event of a GPS system failure, the network would allow an aircraft to tune in a VOR within 100 nautical miles, navigate to it and shoot an approach to get safely on the ground. In much of the country, this means the FAA can shut down a number of VOR’s, which will save funding and help keep the remaining network healthy.

The Alaska case
In briefings in Alaska, the FAA has repeatedly stressed they don’t plan to shut down ANY VORs in the state. That is good, as Alaska has never met the standard that the FAA is reducing the rest of the nation to. But it doesn’t mean that the FAA won’t reduce the number of instrument approaches.

In the national list of procedures the NPRM plans to decommission, there are 28 Alaskan approaches at 22 airports across the state that would go away. There is a cost to maintaining instrument procedures, so if these aren’t needed, it is good to save those resources, as we certainly have other areas still in need of IFR infrastructure.

List of Alaskan approaches proposed for decommissioning.

List of Alaskan approaches proposed for decommissioning.

Instrument pilots are encouraged to study the Alaska list carefully, and speak up if any procedures on the list are still needed. Comments are due by May 28, and may be submitted online, or by mail to: Docket Operations, M-30; U.S. Department of Transportation (DOT), 1200 New Jersey Avenue SE., Room W12-140, West Building Ground Floor, Washington, DC 20590-0001. And please email me a copy of your comments, to help AOPA track this issue in Alaska.

When to switch to VLOC on an ILS or VOR approach?

VLOC SAC ILS VORHard to believe, but the ubiquitous workhorse IFR GPS receiver, the Garmin 430, was introduced 17 years ago in 1997. With more than 100,000 Garmin 430s and 530s shipped, it still has the largest installed base of any IFR-capable GPS. Yet despite its longevity, pilots are still asking basic questions about it, such as “When should I Load versus Activate?” or “When do I switch to VLOC on an ILS or VOR approach?”

Lest you think any of these questions are trivial, the former question became a full page in my Max Trescott’s GPS and WAAS Instrument Flying Handbook. As for the latter question, there’s finally an official FAA answer and surprisingly, it’s different depending upon whether you’re flying an ILS or a VOR approach.

For a lot of people flying mostly ILSs into the same few airports, the answer may seem simple. They might respond “Well the CDI just switches automatically to VLOC as I’m about to intercept the final approach course.” That is true some of the time, though only for ILS approaches and only if you’ve turned on the ILS CDI Autocapture in the Garmin 430 or 530’s AUX group.

But the automatic switching on an ILS only occurs if you intercept the final approach course between 2 to 15 miles outside the Final Approach Fix (FAF). That’s not a problem for most ILSs, but for a really long one with a large descent of perhaps 5,000 feet or more (e.g. the ILS 31 at Salinas, Calif. or the ILS 32R at Moffett Field, Calif.) the CDI won’t switch automatically as you join the final approach course. In these cases, you’ll need to manually switch it. Of course, you’ll always need to manually switch it for any non-ILS approach that uses a Nav radio, such as Localizer, VOR, VOR/DME, LDA, SDF, and Localizer back course approaches.

How Late Can You Switch?
But when are you required to switch to the Nav radio for primary guidance? Imagine you’re on a checkride and you forget to switch the CDI from GPS to the Nav radio. How far can you proceed along the approach before you fail the checkride because you didn’t switch the CDI to the Nav radio?

The story I heard years ago—but never confirmed so I don’t know if it’s true—was that Garmin and Cessna gave differing guidance on this point, because they were located in different FSDOs and got different guidance from their local FAA regional offices. One said you had to switch the CDI or HSI to the NAV radio as soon as you turned onto the final approach course. The other said that you didn’t have to make the switch until you reached the FAF. Which is correct? Like most things in life, it depends!

The FAA reference for this is AC 90-108, dated March 3, 2011. For an ILS, localizer, LDA, or localizer back course, Section 8. c. says that an RNAV System (e.g. a GPS) cannot be used for “Lateral navigation on LOC-based courses (including LOC Back-course guidance) without reference to raw LOC data.” This means that as soon as you turn onto a localizer or ILS, you need to display course guidance from the Nav radio. On the Garmin 430/530, that means as soon as you turn onto the localizer, you must push the CDI button so VLOC is displayed.

But oddly for a VOR approach, the answer is different. Section 8. b. says that an RNAV System (e.g. a GPS) cannot be used as a “Substitution for the NAVAID (for example, a VOR or NDB) providing lateral guidance for the final approach segment.” The final approach segment always starts at the FAF, which is marked with a Maltese cross. So on a VOR approach, you can fly all the way to the FAF before you need to switch the CDI or HSI to the Nav radio. Fly past the FAF using just the GPS (as I saw a client do a few days ago) and you’ve busted your checkride, and the regulations if you were to do it for real on an IFR flight plan.

How Early Should You Switch?
Waiting until the last possible time to switch the CDI or HSI to the Nav radio rarely makes sense. My guidance to clients is when the controller first begins issuing vectors—meaning you’re no longer using the GPS for primary guidance—switch the CDI or HSI to the Nav radio (unless of course you’re flying a GPS approach). That gives you time to verify that the course is set correctly before you join the approach course.

I saw a great example of why that’s important while teaching last weekend at a Cirrus Pilot Proficiency Program (CPPP) in Concord, Calif. One of the attendees I flew with didn’t switch the HSI to the Nav radio until the moment he turned onto the final approach course for the LDA RWY 19R at KCCR. At that time, I noticed that the HSI’s course pointer was incorrectly set for 191 degrees rather than the 181 degrees required for the approach, but didn’t say anything because I wanted to see if and when he’d catch the error. Had he made the switch earlier, he would have had more time to review his setup and possibly catch this error.

The needle remained centered, though it was pointed 10 degrees away from our heading. As we crossed the FAF, he asked “Now do I turn ten degrees to follow the pink line to the airport?” I was stunned that he came up with that as a possibility, since localizer signals are always beamed out in a straight line with no turns. Clearly he knew there was a problem in the conflicting information he was seeing, but he never considered the possibility that the course was set incorrectly.

The mantra I teach clients is to review “MORSE, Source, Course” as part of their setup for an instrument approach. There’s no need to check the MORSE code ID or to set the CDI Course when flying a GPS approach, but they’re absolutely essential to check and set anytime you’re using the Nav radio.

Why Does the FAA Allow the Switch to Occur Later for a VOR
So why must you switch to the Nav radio as soon as you turn onto an ILS or localizer, but can wait until the FAF to make the switch when flying a VOR approach? Consider an instrument approach with a VOR at the FAF. You might guess that when on the approach outside the VOR, a GPS signal keeps you closer to the centerline than a VOR signal, but that’s only true when you’re more than 6 NM from the VOR. At that point, the GPS is in Terminal mode and full scale CDI deflection is ±1 NM, which matches the ±10° full-scale deflection for a VOR signal at that distance.

Six miles is probably close to the average length of an intermediate segment, so while I have trouble saying these words [choke], the VOR would actually be more precise for navigating the last six miles to the FAF. Yes, a VOR signal scallops around a lot, but usually not much when you’re that close to a VOR.

The real benefit of GPS accuracy when flying a VOR approach occurs when you’re flying the initial segment, almost all of which would be more than 6 NM from a VOR at the FAF. Not only would GPS keep you closer to the centerline, but more scalloping occurs on a VOR signal at that distance.

It’s a little tougher to do the same analysis on an ILS or localizer approach, since the beamwidth of the localizer varies between about 3 to 6°, depending upon the particular installation. Suffice it to say that any approach with a localizer will have a narrower beamwidth, keeping you closer to the centerline, than a VOR approach when at the same distance from the antenna site. Just remember that localizers are more precise, so the FAA wants you to start using the Nav radio as soon as you turn onto one. But VORs are less precise, so you don’t have to switch to the Nav radio until you reach the FAF.

Postscript
After reading this post, a friend emailed suggesting I’d misinterpreted AC 90-108 and came to the wrong conclusion about needing to switch to localizer data as soon as you turn onto the final approach course. I sought clarification from AFS-470 at FAA HQ and they quickly responded confirming that pilots MUST use raw localizer data for primary guidance along the entire localizer. They raised an additional point that a reader also mentioned  in the Comments section. Both pointed out that a pilot can always monitor RNAV (GPS) data as they fly along a localizer. However they cannot use it for primary navigation. The pilot must have raw LOC data displayed on their primary instrumentation and  must use that LOC/VOR data for primary navigation. My thanks to everyone who contributed to this discussion!

Instrument Changes: Approaches without IAFs and Vectors to Fixes

 

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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)

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.

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