How Many Engineers Does it Take?

OAK 09/200 OAK NAV VORTAC OTS TIL 1010312359

The Oakland VORTAC has been out of service for, well ... I think it was NOTAMed back in April or May of 2010. Pretty amazing when you consider this is one of the major navigation aids on the West Coast: It defines six Victor airways, six Jet airways, and numerous airports have instrument approaches, departure procedures, and arrivals that rely on it. So what is the FAA doing to the Oakland VORTAC and why is it taking so long? This isn't the entire story, just some of the pieces.

The Oakland VORTAC was missing in action for an extended period about six years ago when a range of radials had become unusable and an effort was undertaken to figure out why. Around that time the Ron Cowan Parkway had just been completed, named after the developer of the nearby Harbor Bay business and residential developments.

Sometimes called the road to nowhere, the project to build the Cowan Parkway figured in an FBI probe that started after allegations of impropriety between Mr. Cowan and then state senator Don Perata. It seems that some folk thought the road was primarily designed to increase the value of Mr. Cowan's real estate holdings at Harbor Bay at taxpayer expense, but that's a deep topic. So moving on I'll point out that the Cowan Parkway divides the Oakland Airport in half, provides alternate access to the FedEx ramp and the South Field terminal as well as an alternate route for residents of Bay Farm Island. Cyclists also benefit from bike lanes that flank the road.

Building the parkway was a big project, in part because a tunnel had to be constructed under Taxiway Bravo, the only connection for taxiing aircraft between Oakland's South Field and the North Field. In addition, airport perimeter barriers had to be adapted and new chain link fencing and razor wire installed. After investigating, it was determined that the new fences were close enough to the VORTAC that they were distorting the signals. Sections of the fencing were replaced with redwood (which you can see in the photo above), the FAA's flight check aircraft conducted various tests, there were still some radials in the Northwest quadrant deemed unusable, but the VORTAC was returned to service and life got back to normal, mostly.

Recently an initiative was undertaken to dopplerize the Oakland VORTAC to increase its accuracy and eliminate or reduce the number of unusable radials. This is the project that started in earnest last spring and after a month or so, a bunch of little mushroom-shaped antennae were seen ringing the main bowling pin antenna.

In July the flight check aircraft was testing the results. I remember one of the days because the FAA's flight check King Air made quite a stir, flying the OAK VOR RWY 9R approach when all other traffic was landing runways 29, 27 Left and 27 Right. A student I was flying with had to break off a practice approach, but I didn't mind because I assumed this meant progress was being made. Yet as the end of July approached, the NOTAM was changed to show the VORTAC returning to service at the end of September. Then I got wind of some of what was going on.

It seems that the new configuration failed the high-altitude flight check and a new effort was underway to determine why. At one point a theory was that surplus concrete debris that the airport facilities folks use to repair the numerous dikes and levees around the airport was causing the problem. The concrete chunks were piled up near the VORTAC, some of the chunks contained rebar, and the thought was this was distorting the VORTAC's signals. This isn't the first time rebar has affected aviation at Oakland: A few years ago it was discovered that both compass roses had been constructed with concrete that contained rebar, which could explain why so many compasses that were swung at Oakland seemed screwed up. The compass roses remain closed.

USD 05/081 NUQ AIRSPACE SOUTHLAND ONE DEPARTURE... NA EXCEPT FOR AIRCRAFT EQUIPPED WITH SUITABLE RNAV SYSTEM WITH GPS. OAK VORTAC OTS.

USD 05/083 LVK AIRSPACE LIVERMORE ONE DEPARTURE... PROCEDURE NA EXCEPT FOR AIRCRAFT EQUIPPED WITH SUITABLE RNAV SYSTEM WITH GPS. OAK VORTAC OTS.

USD 05/085 SFO AIRSPACE PORTE THREE DEPARTURE TAKE-OFF RUNWAYS 10L/R AND 19L/R: PROCEDURE NA EXCEPT FOR AIRCRAFT EQUIPPED WITH SUITABLE RNAV SYSTEM WITH GPS. OAK VOR OTS. 

USD 05/097 SFO AIRSPACE SHORELINE ONE DEPARTURE...
PROCEDURE NA EXCEPT FOR AIRCRAFT EQUIPPED WITH SUITABLE RNAV SYSTEM WITH GPS. OAK VORTAC OTS. 

USD 05/082 OAK AIRSPACE SKYLINE THREE DEPARTURE...
RWYS 9L, 9R, 11 NA EXCEPT FOR AIRCRAFT EQUIPPED WITH SUITABLE RNAV SYSTEM WITH GPS. OAK VORTAC OTS.

USD 05/084 OAK AIRSPACE MARINA FOUR DEPARTURE...
NA EXCEPT FOR AIRCRAFT EQUIPPED WITH SUITABLE RNAV
SYSTEM WITH GPS. OAK VORTAC OTS. 

USD 05/149 OAK AIRSPACE SALAD ONE DEPARTURE NA EXCEPT FOR AIRCRAFT EQUIPPED WITH SUITABLE RNAV SYSTEM WITH GPS. OAK VORTAC OTS.

USD 05/087 CCR AIRSPACE BUCHANAN NINE DEPARTURE PITTS TRANSITIONS: NA EXCEPT FOR AIRCRAFT EQUIPPED WITH SUITABLE RNAV SYSTEM WITH GPS. OAK VORTAC OTS.

USD 05/086 APC AIRSPACE LIZRD THREE DEPARTURE OAKLAND TRANSITIONS: NA EXCEPT FOR AIRCRAFT EQUIPPED WITH SUITABLE RNAV SYSTEM WITH GPS. OAK VORTAC OTS.

Another repercussion has been that a local freight carrier cannot use the SALAD ONE departure because many (or all?) of their aircraft are not RNAV equipped. So instead of departing runway 27L or 27R, turning East over the San Leandro Bay, and intercepting the 060˚ radial, they have to fly heading 310 until high enough to be vectored to the East. The 310 heading takes them right over residential areas of Alameda late at night and in the early morning hours.

Pilots who wish to fly the HWD LOC/DME RWY 28L approach are required to be flying aircraft equipped with a suitable RNAV system because the missed approach holding fix is (wait for it) ... the Oakland VORTAC. I got bitten by this one a couple of weeks ago when the weather into Hayward didn't clear as forecast. My student had to fly the ILS into Oakland, then we sat and waited for VFR weather so we could reposition back to nearby Hayward. Live and learn.

VORTAC with new Counterpoise

I don't know if the theory about rebar in scrap concrete interfering with the VORTAC was itself scrapped, but the latest development was an assessment that the counterpoise (the roof of the VORTAC building) was too small. An effort was undertaken to enlarge the roof, increasing its diameter by some 16 feet to a total diameter of 84 feet. It looks like this part of the project is mostly completed and the latest NOTAM claims the OAK VORTAC should be back in service by the end of October, 2010.

In 2002, the man for whom the road was named defaulted on over $43 million in loans from Lehman Brothers and the investment bank and its property management company seized much of what Cowan owned at Harbor Bay Business Park. The road itself is not heavily travelled, though it did end up reportedly costing taxpayers over $100 million. The road appears indirectly responsible for trouble faced by pilots and a noise-sensitive community. The weather is bound to get worse as winter approaches and fixing the Oakland VORTAC could go down to the wire. We'll just have to wait and see if the FAA can pull a rabbit out of their hat or if the Cowan Parkway will continue to be the gift that keeps giving.

GPS Transition, Part II - Waypoints 'n Stuff

Once you understand how dead reckoning and VOR concepts relate to the world of GPS, you’re ready to move on to waypoint sequencing and turn anticipation. Understanding these two concepts is fundamental to the effective use GPS flight plans, the handling of ATC routing changes, and to reducing the likelihood that you’ll find yourself asking “Why’s it doing that?”


Waypoint Navigation




One goal of RNAV was to simplify navigation from the pilot's point of view and GPS generally offers significant improvements in navigational accuracy and flexibility. Okay, the equipment manufacturers have made things difficult with questionable user interface designs. The FAA and its contractors have created complicated procedures that expose levels of detail that could (and should) be opaque to pilots, but we'll go down that rabbit hole later. For now consider that there are really just two conceptual steps to waypoint navigation: Enter a waypoint into the GPS receiver, then navigate to the waypoint using the desired track and current track provided by the GPS. Don't forget to set your course pointer or OBS to the DTK supplied by the GPS or you'll see a message like the one shown above.


In its most primitive form, waypoint navigation means pressing the GPS receiver's Direct-to button, but you can also enter a sequence of waypoints (aka GPS Flight Plan) and this is where waypoint sequencing and turn anticipation come into play. The mechanics of creating, storing and activating GPS flight plans vary by brand and model of GPS, but for now we’re just talking about concepts.


Shake a Leg


Navigating the desired track (think magnetic course) between two waypoints in your flight plan is referred to as leg flying, which is different from just proceeding to a waypoint from your current position using the direct-to button. Proficiency training with a specific GPS unit should include demonstrating that you understand the difference by proceeding direct to a waypoint as well as activating a flight plan leg, then interceping and flying that leg.

The active leg is usually shown as a magenta line on the moving map whereas previous and subsequent legs to be flown are shown as white lines.

Best Laid Plans


For VFR flying, you can use any waypoints you want in your GPS flight plan; VORs, airway intersections, airports, visual reporting points, or anything else contained in the GPS database. You’ll still want to ensure you're steering clear of restricted airspace, active MOAs, and terrain or weather that might make you wish you were doing something else.


For IFR, your GPS flight plan should ideally match your IFR clearance. This is where the perfect, sequential, tidy world of GPS meets the rough and tumble, real-world of ATC vectors and amended clearances. Start by entering your departure airport and your destination airport. It would be nice if you could enter an alternate airport, but amazingly, most GPS units (save the discontinued G480/CNX80) still don’t support this concept!


IFR clearances may specify a SID (Standard Instrument Departure) or they may specify a heading to fly until ATC vectors you to join the en route structure. Most IFR-certified GPS allow you to load a SID based on your departure airport (the first airport in your flight plan). If the SID has more than one transition to the en route structure, the GPS will prompt you to specify the transition that ATC assigned. Loading a SID often requires you specify the departure runway and this can be especially critical for RNAV SIDs. Loading a SID will insert all the necessary waypoints into your flight plan.

Some SIDs are pilot-nav, the theory being that you fly the procedure with minimal input and guidance from ATC. Other SIDs are vectored, with the assumption that ATC will guide you to the en route structure. Many older GPS units don’t provide a way to load a vectored SID, so just enter the waypoint (usually a VOR) that defines the transition to which ATC is going to guide you. Either way, it's not uncommon for ATC to assign you headings to fly in order to separate air traffic, eventually telling you something like “when able, resume the Wild Goose Chase departure ...” This is where activating the appropriate leg from your GPS flight plan is a need-to-know skill.


Anytime you are being vectored, the heading you are flying may not correspond to the magenta line that the GPS is depicting. This often causes concern for an RNAV tenderfoot, but remember that the compass and heading indicator are also IFR instruments and you won’t always be following the GPS’s magic, magenta line.


Defining Victor or Jet Airways for the en route portion of a GPS flight plan is fairly straightforward: Just enter the name of each VOR and any changeover points in between. Some newer GPS units provide a way to load an airway and will fill in the necessary waypoints for you, but the process can be convoluted. The idea is you start with a waypoint on the airway that ATC has assigned, then select the airway you want to load from a list of possibilities, and then specify where you want to get off the airway. This will add the necessary waypoints to your GPS flight plan.


Loading a STAR (Standard Terminal ARrival) or IAP (Instrument Approach Procedure) for your destination will require you to specify the transition (where you want to enter the procedure). Loading these procedures will add waypoints to your flight plan. And like a SID, you may get vectored around by ATC and you’ll need to know how to proceed direct to a waypoint or how to activate and join a leg of the procedure.


So a GPS flight plan is just a collection of waypoints that you either entered yourself or that were added when you loaded a departure, arrival, or approach procedure. If all goes as planned, you’ll fly to each of those waypoints in a nice, orderly sequence. Scratch that. Things never go as planned, so you need to know how to find your way through the flight plan and navigate direct to a waypoint or how to activate a leg.


Fly-Over vs. Fly-By


Now that you know (at least a bit) about GPS flight plans, let’s revisit waypoint sequencing. GPS keeps track of where you are and as you reach the current waypoint, it usually sequences to the next waypoint, calculating the new desired track, distance, time en route and other stuff in the process. Yet there are times when a GPS won’t automatically sequence to the next waypoint and it’s important to understand the when and why this will occur.

The majority of the waypoints in your GPS flight plan are called fly-by waypoints, usually depicted on charts as a four-pointed star. As the name implies, you don’t have to fly directly over these waypoints. Since the GPS knows your groundspeed, current track, and the number of degrees of change between the current DTK and the upcoming DTK, it can provide turn anticipation for fly-by waypoints. If you pay attention, follow the GPS’s advance warning and turn when it says to turn, you’ll end up on the new DTK. Old school pilots who were taught to fly past a VOR, verify station passage, then turn to the new course may find they have trouble letting go of their old habits. Just keep reminding yourself that turn anticipation is a good thing.

Another type of waypoint is called fly-over. As the name implies, you must fly right over a fly-over waypoint. Try as I might, I couldn't find a definition of just how close you must pass to a fly-over waypoint but my personal experience is that it's pretty damn close. One example of a fly-over waypoint is the missed approach waypoint on an IAP: Fly over the MAP and you’ll have to push a button to re-enable waypoint sequencing to the missed approach segment (on most GPS units). Same holds true for most missed approach holding waypoints. Which button you push to re-enable waypoint sequencing depends on the brand and model of GPS.


Some RNAV SIDs and STARs have fly-over waypoints, depicted as a four-pointed star enclosed in a circle, but waypoint sequencing is not suspended for these waypoints on a SID or STAR; The procedure designers just want you to navigate to these waypoints very precisely.

You can manually suspend waypoint sequencing for any waypoint at any time by pressing a button. Depending on the brand of GPS receiver you're using, the name of the button or softkey may be OBS or it may be SUSP, but press that button or softkey and the GPS won't sequence from the current waypoint until you intervene with another button push: Pretty handy when ATC tells you to fly an ad hoc holding pattern using the current waypoint as the holding fix.


Many pilots ask why some GPS receivers call this feature OBS and I the reason is that pressing that button lets you treat the current waypoint as though it were an old-fashioned VOR: You can turn your course selector or OBS knob and set whatever DTK to the waypoint you want. When you press OBS or SUSP, you’ll see a magenta line on your moving map leading to the waypoint on your selected DTK and a white course line extending outward on the opposite side of the waypoint.


Missed Opportunities


GPS receivers allow pilots to load all sorts of instrument approaches, thereby adding the necessary waypoints that make up the approach to the GPS flight plan. Monitoring a moving map to maintain situational awareness during an approach is cool, but the waypoint sequencing get's messed up when you are being vectored to intercept the approach. When being vectored, the first task is to activated the correct leg of the approach so that the GPS will sequence through the waypoints in your flight plan in the correct order as you fly the approach. For a detailed discussion of this issue with Garmin units, go here.


Lastly, consider the location of the missed approach fly-over waypoint (MAP) for an ILS or an RNAV approach with vertical guidance (LPV or LNAV/VNAV). For approaches with vertical guidance, the MAP waypoint is defined by centered localizer/LNAV and glide slope/VNAV needles at the Decision Height (DH). Consider also that the FAA puts ILS and localizer-only approaches on a single approach chart as it does for RNAV LPV and LNAV/VNAV approaches. GPS designers had figure out how to handle this and they came up with this kludge: They consider the MAP waypoint to be at the runway threshold. The MAP waypoint is given a name like RW34 for “runway 34.”

In the example above, you reach the DH, see nothing but clag, and start the missed approach. The GPS will not have yet suspended waypoint sequencing since you haven’t arrived at the runway threshold, so you’ll need to fly over the runway threshold before you can activate the missed approach. Oddly, the Garmin G1000 provides an Activate Missed Approach feature, but every time I’ve tried to access that feature it had a grayed-out appearance and couldn't be selected.


Stay Ahead, Keep Ahead


Now you know a bit more about the crucial foundations of RNAV: The importance of automatic waypoint sequencing, the role of a GPS flight plan, how your GPS flight plan may not conform to the real world, and the important difference between direct-to and leg navigation. You've probably noticed that we're delving into increasingly complex RNAV concepts, so stay tuned for my next installment: Creeping RNAV complexity and what you can do to combat it.

Something Can Be Done

The promise of Area Navigation (RNAV and GPS) was that it would be a simpler and more accurate way to navigate than older styles of navigation and to a great extent, that promise has been realized. GPS accuracy, especially when augmented with WAAS, is very good indeed. As for simplicity ... not so much. Waypoint navigation was a revolutionary concept when it was introduced, but it has been integrated with existing navigational paradigms and infrastructure in an evolutionary manner, not unlike the way an artist might sculpt clay or mold papier-mâché. This evolutionary approach has created some unfortunate and unforeseen complexity, but it doesn't need to be that way. Mom always said "Don't complain unless you can offer a solution or a suggestion," so here are my top five recommendations for simplifying the world of RNAV.

Wayward Waypoints


Many airports out there have a VOR located at airport and in those cases the VOR and the airport have the same name. Just as often the VOR may be some miles away from the airport, but both still have the same name. At the heart of every GPS receiver is a computer running software and software doesn't tend to handle ambiguity very well. That's why the GPS database encodes airports using a four-character ICAO identifier and VORs with a three-character identifier. The FAA's charting division could do us a big favor by using four-character ICAO airport identifiers on their chart products, but they don't. If they did, it would be crystal clear to student pilots and budding instrument pilots that KSAC refers to the surveyed center of the Sacramento Executive airport while SAC refers to the Sacramento VOR. 

Not in Kansas Anymore

The first step in GPS navigation is to enter the name of a VOR or NDB station on the ground, the name of an intersection of two VOR radials, an airport ID (which represents the surveyed center of the airport), a charted VFR reporting point, a Computer Navigation Fix defined by FAA chart designers, or even a user waypoint that you've created. The AIM refers to this type of navigation as to-to, not to be confused with Toto, the little black terrier in the Wizard of Oz. GPS receivers only navigate to one waypoint at a time, also known as the current waypoint.

GPS makes it simple to navigate to a waypoint and most receivers provide a moving map display, which is a score for simplicity and safety. The bad news is that unless you're lucky enough to have a keyboard as part of your GPS receiver, entering a waypoint requires a precise and often convoluted sequence of knob-turning and button-pushing. A bad user interface makes it all too easy to misspell the name of the waypoint: Get just one letter wrong and instead of navigating to a VOR that is 20 miles away, you may be headed to Tierra del Fuego by mistake!

The engineers that designed GPS receiver user interfaces didn't set out to create difficult-to-use products, but the fact is they did. Whether it was the desire to save a few bucks by having fewer knobs and buttons or simply a race to get a product to market, it's clear that mistakes were made. Now the users of these products have to live with the mistakes and to quote Warren Zevon, "… it ain't that pretty at all." Bad UI design is the Achilles heel of GPS and many of us pilots have become so acclimated to these convoluted interfaces that we have lost sight of just how whacked this situation is.

Near the top of my "need to fix" list is Garmin's Small-Knob/Big-Knob interface. You press the small knob to enter "cursor mode" so you can edit or enter the name of a waypoint in a flight plan. You turn the small knob to start the process of entering letters and then the small knob changes function. Whoa there! A knob whose function changes depending on an interface context that is mostly invisible to the user? This needs to be fixed and one simple way would be a separate button dedicated to starting and ending the waypoint editing mode.

Having a separate button for edit mode would also fix the problem that countless new Garmin users run into: Pressing the small knob to exit cursor mode and accept whatever changes they have made. Having watched hundreds of pilots make this mistake thousands of times it's clear that a common intuitive belief is that if you press one button or key to enter a mode, pressing the same button or key should exit that mode. In the Garmin world, this simply exits the editing mode and, here's the amazing part, destroys whatever changes you made without asking you to confirm that's what you want to do. This is B-A-D.

Missing Pieces on the Missed Approach

When flying an instrument approach, most GPS receiver are designed to suspend the automatic sequencing of waypoints when you reach the missed approach point. Think about this for a moment: You're close to the ground with reduced obstruction clearance at a high-workload moment. You're either going to see the runway and land or you won't see anything and you'll fly the missed approach. Is this really the time to make a pilot divert their attention from controlling the aircraft to push the OBS button or SUSP soft-key? I don't think so and apparently neither did the designers of the GNS 480 (nee CNX 80), which will automatically sequence to the missed approach segment. If you see the runway environment and decide to land, you just ignore the GPS. If you don't see the runway environment or loose sight of the runway while circling, use the GPS to start navigating on the missed approach. Too bad the GNS 480 is out of production and the GPS units that are in production don't exhibit this behavior. A defense I've often heard is that the TSO specifies that pilot action is required to initiate the missed approach and if this is true, the TSO should be changed.

When flying a non-RNAV approach, many GPS receivers automatically switch the navigation source from GPS to the VOR or localizer receiver. That's great, but if you need to fly the missed approach and you want to use the GPS to do so you must divert your attention and manually select GPS as the navigation source. I mean really! If it's okay to automatically switch navigation source out of GPS, why not back into GPS mode?

Four Card Minima

There's a new game for RNAV approaches that all pilots must play and it's called "Guess the approach minima." It goes something like this. When you brief an RNAV approach, you may see up to four sets of minima listed: LNAV, LNAV/VNAV, LPV and circling. The issue is you may not know which minima your WAAS GPS receiver can offer (based on current signal integrity) until a few miles before the final approach fix. This has to do with the design of WAAS GPS receivers' final signal integrity check and I honestly can't think of a good way around this shortcoming: You just have to brief multiple approach minima and choose the correct minima based on the approach sensitivity your WAAS GPS receiver displays.

Where improvement could be made would be to ensure that the approach sensitivity displayed on the GPS receiver exactly corresponds to the approach minima shown on the chart. If your receiver arms with  LPV or LP sensitivity, you're okay because your WAAS GPS receiver should display LPV or LP. If the receiver arms with LNAV sensitivity, you may see LNAV or LNAV+V. If it arms with LNAV/VNAV you'll probably see LNAV/V. Notice the subtle, similar appearance of LNAV+V and L/VNAV? This is too subtle and is B-A-D. And the minima shown on the charts should exactly match the minima displayed on the GPS receiver, period, end of discussion.

Procedure Turn or No?

The introduction of the Terminal Arrival Area (or TAA) was meant to simplify pilot/controller interaction when executing an RNAV approach. And it would be simpler, were in not for the fact that not all RNAV approach charts follow the same conventions with regard to the depiction of a hold-in-lieu-of procedure turn (or HILO). In particular, some RNAV approaches have a standard Minimum Safe Altitude circle while others display minimum safe altitudes in sectors on the plan view of the chart. The subtle problem is that MSA sectors will usually tell the pilot that the procedure turn is not authorized when you're headed straight-in to an Initial Approach Fix where a HILO is depicted, while approaches with the MSA circle do not.

If you were approaching from the Southeast and were told "when able, proceed direct HERMIT, cleared RNAV 34 approach" you need to read the fine print on the MSA sector shown on the plan view to know when you could descend and to know that the HILO is not authorized.

If you were told "when able proceed direct CADAB, cleared RNAV 29 approach," you need to know that the hold-in-lieu-of procedure turn is required unless the the controller remembers to say "… cleared straight-in RNAV 29 approach."

The FAA charting division needs to come up with a consistent way of depicting MSA and clearly denoting when a procedure turn is required and when it isn't. Until then, pilots should ask the controller when they see a HILO and they aren't sure whether or not they are expected to fly the procedure turn.

More Fond Wishes

So that's my wish list of the top five features and enhancements I'd like to see for the world of RNAV. You may have your own list of desired features, too. For now, we can only hope that the people in a position to fix these issues are listening.

Hold Everything, Part III

For being so simple, holding patterns are a surprisingly deep topic. In this installment I'll cover some subtle points like orientation on the outbound leg, when to start timing, the 5 Ts, Dealer's Choice Entry, wind correction, station side holds, and the so-called Crisis Entry.

You Gotta Believe
When a photojournalist is mired in a crowd of people and is unable to see the subject they are trying to photograph, they often hold their camera up, point it in the generally correct direction, and click the shutter in hopes of getting a usable shot. This used to be called a Hail Mary, a term also applied to a quarterback throwing a football a great distance downfield in hopes that his receiver will be there to catch it.

An aviation equivalent of a Hail Mary is something that many new instrument pilots have a hard time grasping: Without a GPS depiction of a holding pattern you really have no positive course guidance on the outbound leg. On the inbound leg, the CDI or HSI will be centered and the ADF needle should basically be pointing straight up (aside from any wind correction angle).

If you're navigating with a VOR or ADF, you cross the fix, turn outbound, fly for a minute and see what happens when you turn inbound. If you have an idea of the winds aloft prior to entering the hold, that knowledge can certainly inform your choice of heading; more on that later.

With a GPS depiction of the holding pattern, you'll have an excellent idea of where the desired outbound leg is. Some GPS receivers capable of depicting holding patterns will even change the shape of the holding pattern race track to account for your aircraft's speed and for wind correction.

Here's the G1000's predicted holding pattern shape at 145 knots with winds out of the NNE at 25 knots.


Here's the same predicted holding pattern shape after slowing to 105 knots.


Without GPS, the first time around the hold is often a bit of a gimme - You get a better idea of the winds aloft and refine the hold with each lap you fly. This can be a good thing if you have to hold for a long time because it gives you something to do and relieves the boredom.

Five is Enough
A popular checklist mnemonic used as you cross a holding fix (or any other fix, for that matter) is the Five Ts. Some instructors teach a slightly different order and some even teach more than Five Ts. Here's my version:

• Turn - to the outbound heading
• Time - start your time, if necessary
• Twist - twist the course pointer or OBS to the INBOUND course, if necessary
• Throttle - reduce to holding speed if you haven't already done so
• Talk - report entering the hold

Some folks insist that you start timing before you start turning, but it doesn't really matter as long as you are consistent in which you choose to do first. I teach turn before time because it works well when flying one of those rare instrument approaches that have a course change over the final approach fix.

I've seen pilots and instructors who insist on twisting the OBS or course pointer when turning outbound as well as when turning inbound in the hold. That seems a bit kooky in light of the above discussion of course guidance on the outbound leg, but I guess it's harmless as long as you keep your situational awareness.

I rarely see pilots report entering the hold, even though it's one of the compulsory reports under IFR. The format goes something like this:

Barnburner 123, entered the hold, Sacramento, 2132 Zulu.

Get Your Fix
An often misunderstood concept is when to start timing the outbound leg of the hold. When you are entering a hold using a teardrop or parallel entry, start the outbound timing when you cross the fix. When flying a direct entry or once established in the hold, start timing abeam the holding fix provided you can determine that position.

Station passage over a VOR occurs on a teardrop or parallel entry as soon as your VOR receiver shows a positive reversal of the To/From flag. For a hold over an NDB, your ADF needle will start to point behind your wing when you've passed the station. If you are holding over a VOR intersection or a DME fix on a VOR radial, the equivalent of station passage is when you have passed the cross-radial or DME distance that defines the holding fix.

If you are navigating using GPS, you need to suspend waypoint sequencing (by pressing the OBS button) unless you are holding over a missed approach holding waypoint defined in an instrument approach procedure. The nice thing here is that when waypoint sequencing is disabled and you cross the fix, the To/From flag will reverse just like when crossing a VOR station.

If you did a direct entry or are already established in the holding pattern, start timing the outbound leg when abeam the holding fix. Holding over an NDB, abeam the station occurs when the ADF needle is basically pointing off the wing. Holding over a VOR and assuming you set the proper inbound course on your OBS or HSI, abeam the station occurs when the To/From flag flips to TO.

Holding over a GPS waypoint with waypoint sequencing disabled and the proper inbound course set, abeam the station occurs when the To/From flag flips to TO.

When holding over the intersection of two VOR radials, you won't have a good indication of the position abeam the fix unless you are lucky enough to have a cross-radial is perpendicular to the inbound course. In these cases, start timing as you cross the fix and turn outbound, and after a minute you should have completed your 180 degree turn and you can start timing the outbound leg.

Holding over a DME fix on a radial without DME leg lengths, start timing when the DME distance is the same distance as that which defines the holding fix.

Dealer's Choice
When you are approaching the holding fix and your heading is within ±10˚ of the outbound course, it's really up to you as to whether you do a teardrop entry or a parallel entry. One advantage of doing a parallel entry is when winds aloft are strong. With a strong wind perpendicular to the inbound and outbound courses, tracking outbound on the inbound course provides you with positive course guidance. This means you can determine a wind correction angle for the outbound leg and apply that knowledge to flying the inbound leg.

Here's the missed approach holding for the Stockton ILS RWY 29R. Note that the G1000 is defaulting to a teardrop entry and it's probably best to follow that advice. Without GPS and using just plain old VORs, you could do a parallel or teardrop - your choice.


Wind Correction
When there's a strong wind perpendicular to the inbound and outbound legs, your holding pattern will end up looking egg-shaped rather than the idealized, symmetrical racetrack pattern. In some cases the wind will increase your groundspeed on the outbound leg and decrease your groundspeed on the inbound leg. Unless your holding instructions specified DME leg lengths, you'll need to apply a little trial and error to adjust your outbound timing so that your inbound leg takes a minute.

One rule of thumb is that whatever wind correction angle you needed on the inbound leg should be doubled or tripled in the opposite direction for the outbound leg.

Near Perpendicular Entry
You may find cases where a direct entry has you flying course almost perpendicular to the outbound course.



If you cross the fix and turn outbound, your outbound course will be so close to the inbound course that you're guaranteed to overshoot the turn to the inbound course. In these cases it can be beneficial to cross the fix and wait 10 or 15 seconds before turning outbound to but some distance between your outbound course and the inbound course. In fact, that is what the G1000 is programmed to do in these situations.


Station-side Holds
Remember that step for determining the outbound heading where you ask if the cardinal direction matches the radial? Most of the time they will match, but when they differ is called the station-side hold. This occurs where the holding fix is defined as a DME distance on a VOR radial and the holding pattern is located on the same side of the fix as the VOR station.



Look at this illustration and assuming North is up, it's pretty easy to see that the cardinal direction for this hold would be East, but the radial specified would be 270 degrees. This is where you determine the reciprocal of 270 is 090, write it down as your outbound heading, and turn to that heading after crossing the fix. To navigate on the inbound leg, your CDI or HSI should be set to 270.

Crisis Entry
Try as you might, you may get flummoxed, not be able to determine the entry procedure, and screw up your first trip through the hold. The best thing to do turn back to the holding fix (left or right turn, whichever is shortest), figure out the outbound heading, cross the fix and turn outbound again. You don't want this to happen on a check ride, but everyone makes mistakes from time to time. In real life, think of it as a mulligan or a do-over.

This concludes my series on holding. I hope you've found it helpful and enlightening!

Hold Everything, Part II

Barnburner 123, hold East of the Sacramento VORTAC on the 080 radial, 4 mile legs, left turns, maintain 5000, expect further clearance in 40 minutes.

In this hypothetical example you'll see that entering a hold involves just a few basic tasks:

• Fly to the holding fix
• Cross the fix
• Turn outbound in the appropriate direction.
• After a minute (or a minute and a half above 14,000') or the specified DME leg length, turn inbound.
• Rinse and repeat

The heading you turn to after crossing the holding fix depends on your orientation to the outbound leg, but it is crucial that you know the outbound course. If you are flying a hold that is part of a published procedure, you can just read the outbound course right off the page. If you've been given holding instructions that are not published, start with step 1.

Step 1 - Write down the instructions and read them back
First things first. Don't worry about figuring out the entry at this point, just write the instructions down and confirm with the controller that you've got it right. It helps to know the elements of a holding instruction, the order in which those elements will be given, have a shorthand for recording those instructions, and above all, stay relaxed and ahead of the game. If the controller tells you they have holding instructions and you're not ready to copy, tell them to standby until you are ready.

Taken in order, a holding instruction should contain:

• Cardinal direction of the OUTBOUND leg (North, NE, E, SE, S, SW, W or NW)
• Holding fix (a VOR, NDB, intersection, or GPS waypoint)
• Radial, course, bearing, airway, or route
• Optional leg length in miles (if not specified, 1 minute legs, 1.5 minute legs above 14,000' MSL)
• Optional left turns (right turns assumed if this is omitted)
• Time to expect further clearance (usually to leave the holding pattern)

Here's how it might look after you've recorded these holding instructions.

Step 2 - Fly to the Holding Fix

If the holding fix is a VOR or an NDB, this is basic radio navigation that any proficient instrument pilot should be able to do while half asleep. Come to think of it, when I worked as a freight dog I often felt like I was half asleep!

If the holding fix is the current GPS waypoint, you best press the OBS button to suspend waypoint sequencing.

Within a few miles of the holding fix, begin slowing to your holding speed.

Step 3 Determine the Outbound Course

This step is crucial and there are a few questions you need to ask to determine the outbound course:

Does the cardinal direction (N, NE, E, SE ...) match the radial or bearing?

• If YES, the radial or bearing is the outbound course.
• If NO, the reciprocal of the radial or bearing is the outbound course.

A quick way to compute the reciprocal of a radial is to add 200 to the radial and subtract 20 or, subtract 200 and add 20. Most people find this to be easier than trying to add or subtract 180.

In this example the radial and the cardinal direction match so the outbound course is 080 degrees.

Step 4 Write down the Outbound Course

Don't leave this to chance! In a high workload moment, you may forget, then get flummoxed and blow the hold entry.

Step 5 Determine the Holding Pattern Entry

I've illustrated the next step using a G1000 HSI set to GPS, but the same technique applies to a course deviation indicator set to a VOR.

If the direction of turns wasn't specified, right turns are implied, so place your right thumb at the three o'clock position on the heading indicator or the HSI.

If left turns were specified, place your left thumb at the nine o'clock position on the heading indicator or the HSI.

Either way, your thumb should block out about 20 degrees above the three o'clock or nine o'clock position on the HSI (or CDI).

Imagine a horizontal-ish line from the top edge of your thumb that travels through the center of the HSI or heading indicator to the other side. Imagine a vertical line from the center of the HSI or heading indicator up to the twelve o'clock position.

Next, locate the OUTBOUND course you determined in step 3 on the HSI or heading indicator.

Direct Entry
If the OUTBOUND course is located on the HSI below the imaginary horizontal-ish line, do a direct entry .

Fly to the fix and turn in the specified direction to the OUTBOUND course. After a minute (or minute and a half above 14,000') or the specified leg length, turn in the specified direction back to intercept the inbound course.

Teardrop Entry
If the OUTBOUND course is located between the vertical line and your thumb, do a teardrop entry.

The initial outbound heading for a teardrop entry requires just a bit more math.

Start with the outbound course you determined above and think LARS: Left turns, Add 30 degrees, Right turns, Subtract 30 degrees to get your initial teardrop outbound heading and write it down. Crossing the holding fix, turn to the teardop outbound heading. After a minute (or minute and a half above 14,000') or the specified leg length, turn in the specified direction back to intercept the inbound course.

Parallel Entry
If the OUTBOUND course is located between the imaginary horizontal-ish line and the imaginary vertical line, do a parallel entry. In the example above, a parallel entry would be appropriate for entering the hold at Sacramento.

Fly to the fix, turn to the outbound course, and track outbound on the inbound course. After a minute (or minute and a half above 14,000') or the specified leg length, turn OPPOSITE the specified direction back to intercept the inbound course. You will need a pretty aggressive intercept angle (35 to 45 degrees) to intercept the inbound course before reaching the holding fix. After crossing the holding fix, all turns will be in the direction specified in the holding instruction.

Looks like there are a few more details to cover, so stay tuned for part III.

Hold Everything

Piper 123, I have some good news and some bad news. Which would you like first?

We'll take the good news first.

Piper 123, when able, proceed direct Scaggs Island. The bad news is climb and maintain 6000, hold Northwest of Scaggs on the 347 radial, left turns, expect further clearance in 50 minutes.

Direct Scaggs, hold Northwest, 347 radial, left turns, 6000, further clearance in 50 minutes.

And Piper 123, I'm working with Norcal to get you in as soon as possible and I'll keep you advised.

Okay, we just need to be on the ground before midnight or the plane will be out of annual.

This exchange occurred on a night training flight a few years ago with an instrument rating candidate. We'd gone to a Sacramento area airport, he'd flown an nice ILS approach in a steady rain, executed the missed approach and then asked for our IFR clearance back to Oakland. The surface winds at Oakland had been out of the West when we departed and were not forecast to change, but change they did. Oh, and this was on a Sunday at the end of the Thanksgiving holiday and there was plenty of conflicting airliner traffic headed into Oakland and SFO.

Holding patterns themselves are not difficult to fly, but visualizing the holding pattern and determining how to enter the hold can be vexing in single pilot operations when your workload is high. Once GA pilots pass their instrument check ride, they may not be called upon to regularly demonstrate a holding pattern and it's all too easy to lose proficiency with something you don't use often. There are a bunch of details on holding procedures that often are glossed over, so I'll cover this topic in two separate posts.

A hold can specified in a Standard Instrument Departure (SID) to allow you to climb to a safe en route altitude before proceeding on course.



A hold may be specified in an Obstacle Departure Procedure (ODP) with only a textual description provided.



Standard Terminal Arrival procedures may depict holding patterns that ATC might use to facilitate the flow of traffic.



Many instrument approaches provide a holding pattern to allow you to reverse direction and get aligned with the intermediate or final approach course segment.



A hold is an idealized race track pattern anchored over a holding fix that the pilot can identify with on-board electronic navigation equipment, but the path you end up flying is usually not a perfect racetrack pattern. ATC can't really tell how accurately you're flying the hold. Center radar sweeps about every 12 seconds and a lot can happen in that time period. Approach radar sweeps more frequently, but approach controllers are too busy to spend time critiquing your holding prowess. In my experience, ATC doesn't really care how accurately you're flying a holding pattern as long as you stay at your assigned altitude in the general holding pattern area.

Holds can be over a VOR or Locator Outer Marker, they can be at the intersection of two VOR radials, or they can be on a VOR radial at a specific DME distance.





I often see pilots who try to fly the racetrack in the wrong direction, so let's be clear: Once you are established in the hold, you'll always fly the inbound course toward the holding fix. The turn to the outbound course occurs after crossing the holding fix. The outbound course is located on the holding side and is particularly important when determining the holding pattern entry because you fly to the holding fix and then turn outbound. More on that later.



The term protected side was formerly used to describe the side of the inbound course where you don't usually fly while holding, but this term was not very accurate. The protected airspace around the hold is fairly large and extends well into the non-holding side of the pattern and if you're interested in the gory details of holding pattern construction, check out Order 7130-3A. The preferred terms are now the holding side and the non-holding side. If you stray into the non-holding side you are not going to fly into a mountain or be eaten by a dragon, provided you maintain an appropriate altitude (dragons can't fly very high) and observe the maximum speed for your altitude.

The speed you fly in the hold is important because you want to stay in protected airspace. The usual holding speed limits are 200 knots below 6,000' MSL, 230 knots between 6001' and 14,000' MSL, and 265 knots at 14,000' and above. These speeds are clearly faster than the cruise speed of many light, GA aircraft, but you should still slow down to reduce your fuel consumption.

Holding patterns can be put into two broad categories; published and ad hoc. Published holds, as shown above, may be part of a SID, ODP, STAR, an instrument approach procedure, or they may even appear on an en route chart. Ad hoc holding instructions are made up by ATC on the spur of the moment and while this is rare, it's still something every instrument pilot should be prepared to handle.

Many modern GPS receivers will display hold patterns that are part of a SID, STAR, or instrument approach procedure. The GPS may even suggest the entry procedure. Autopilot-equipped aircraft with newer GPS receivers can even enter and fly the hold for you. Only one GA GPS receiver that I know of, the Garmin GNS 480, allows you to program an ad hoc hold. The bottom line is that your GPS receiver, if you have one, may or may not help you with the entry to the holding pattern. You should be prepared to figure out and fly the holding instructions that ATC throws your way using your little gray cells. More in the next post ...

Start Making Sense

Like many pilots, I subscribe to several aviation magazines and do a lot of reading to keep up to speed on changes and trends in aviation. I find some of them more useful than others. One magazine that I often find disappointing is Flying magazine. I probably wouldn't subscribe to it, but it's a freebie that comes with a membership to a professional organization to which I belong.

One of the reasons I find Flying magazine disappointing can often be traced to the editor, J. Mac McClellan and his opinion pieces. The January 2008 issue contains a McCellan commentary that doesn't fail to disappoint. Sorry if that's too many negatives - I mean to say I found his commentary disappointing because he attempts to explain how easy GPS and RNAV approaches are to execute with the Garmin 530/430 and G1000. Several of his statements irked me, the most obvious being his attempt to lay the blame for pilots' confusion in using these units at the feet of flight instructors and not where it belongs. To paraphrase the old Woody Allen joke, "Manufacturers (like Garmin) and the FAA have built a castle in the sky. Pilots and flight instructors live there."

But if this misplaced blame weren't enough, Mr. McCellan makes several assertions that he probably meant to be helpful, but are factually not true. His overly simplistic advice just might get a pilot into the danger zone. Jumping to the end of the commentary, McCellan closes with this claim:

The great news about WAAS is that just about every instrument approach looks like an ILS, can be flown like an ILS, and you don't need to learn how to do any extra button pushing. I think we want to make this seem hard because it's really so easy.

While the goal of the new RNAV approaches is to provide vertical guidance for every airport, it's not always possible. Sometimes the required WAAS service level is not present and all you get is LNAV with no vertical guidance whatsoever. It may make things more complex, but an instrument instructor would be remiss if he didn't prepare a pilot for such an eventuality.

The commentary starts off fine and there's a lot to agree with. A recurring theme for Mr. McCellan is that navigational systems should be simple and easier to use and I agree that there is a tradition that mires pilots (especially GA pilots) with unnecessary amounts of detail about how things work. Mr. McCellan points out that many GPS instructional courses start out describing the constellation of GPS satellites and include many layers of complexity that have no direct relationship to successfully flying an instrument approach. Then it goes South with this amazing claim.

The box itself, and the instrument approach chart, show you everything you need to fly approaches with WAAS, and they do it automatically with no need for additional training.

He then goes on to describe the Garmin product line in such glowing terms that it makes me wonder if we're using the same equipment. Perhaps someone from that corporation actually asked Mr. McCellan to write this piece to divert attention from the user interface mess they have created. It reads a lot like (gasp!) an advertisement.

But here's the rub that is baffling many pilots and their instructors—you can't modify the procedure if you elect to fly it as published. ... The system won't allow you to skip a holding pattern, for example, if that is part of the published procedure...
... Stay with a vectors to final approach every time you can, and life will be easy. When a full approach is necessary you must understand that a WAAS box will not skip a thing.

With all due respect - Bladerdash!

Consider the RNAV RWY 34 approach to Willits, California.


Assume you are located somewhere near the Mendocino VORTAC (ENI), are proceeding direct to O28 (Willits), and then you learn the weather is not so hot. You request the RNAV RWY 34 approach and Oakland Center clears you "direct HERMT, expect the RNAV runway 34 approach." So you press the PROC button and select the RNAV RWY 34 approach and select HERMT as the transition. As Mr. McCellan points out, selecting and activating an approach is relatively straightforward once you've done it a few dozen times.



Here's where the 530W/430W units are a bit smarter than the older versions. Since the Initial Approach Fix (IAF) you selected has a hold in lieu of a procedure turn, the unit asks if you want to fly the hold. Mr. McCellan's simplistic description doesn't mention this behavior and here's where the FAA's regulatory complexity keeps instrument flight instructors busy. 14 CFR 91.175 says, basically, that in our scenario you shouldn't expect to fly the procedure turn. If you want to do a turn in the hold, say for currency, you need to ask ATC and get their permission.



Let's say that in our scenario we actually want to do a turn in the hold, Oakland Center gives us permission, so we answer YES to this prompt.



We've selected the full procedure. You can see the magenta line leading to HERMT and the hold depicted in white. Mr. McCellan claims that once the holding option is selected, it cannot be changed. Again I wonder if we're using different equipment or if he's in need of some refresher training.




Let's throw a twist into the scenario and say that you just learned that heavy precipitation has been reported 10 miles northwest of the airport and it's moving southeast bound. You decide to skip the hold. Press the FPL button, press the small knob to enter cursor mode, scroll with the big knob so that the hold is highlighted. Now press CLR and when the unit asks if you really want to remove the hold, press ENT. Viola! The hold has been removed. What's more, if the autopilot was engaged in NAV mode and was taking you to HERMT, it will correctly sequence you through the rest of the approach.





I've written before about the dangers associated with selecting Vectors-to-Final when the approach contains stepdown fixes outside the FAF. The short version is that if you take Mr. McCellan's advice then you won't see the intermediate fixes and you might descend into cumulus granitus if you're not careful. There are some new features in the Garmin units that make it a bit easier to handle this and I'll cover that in a future post.

Flight instructors are an easy target for frustrated pilots and for magazine editors who are trying to put lipstick on a hog. The problem with these units is that the user interfaces are a mess and by approving of these units, the FAA's fingerprints are all over them.

It's obvious that many flying magazines are dependent on advertising revenue from aircraft and aviation equipment manufacturers. And I wouldn't be the first person to point out that this often leads the columnists writing for these magazines to avoid taking off the gloves and drawing attention to the flaws and shortcomings in these products. I, on the other hand, have no relationship with these manufacturers and no incentive to ... well ... fib. I receive no income from these manufactures and I'm offering these observations for free to anyone who cares to read this. If you value my unbiased perspectives, please consider making a donation using the link found in the upper right side of this page. The amount you choose to donate is up to you, but it will help me continue to set the record straight.

Oh, and Mac, if you're reading this, feel free to drop me a line next time your in the Bay Area. If you buy me a coffee, I'll give you some free ground instruction in the use of the 530W. Or we can just chat about why you feel the need to blame flight instructors ...

Film at Eleven

Making my way back to the Bay Area by car after a long anticipated Thanksgiving break, I've had a chance to contemplate the last few weeks. Several people commented that I hadn't been blogging lately and asked why. There was really only one reason; I was busier that a one-legged man in a butt-kicking contest. In one 4.5 day period I gave 30 hours of flight instruction in four different aircraft types. For every hour of dual given, there's at least an hour or so of ground instruction. So there were some interesting things to report, just not enough time to write them down.

One flight with an instrument student provided excellent conditions for flying ILS approaches. The 1.8 hour cross-country flight involved only 0.2 hours in visual meteorological conditions and an ILS to minima where the approach lights were barely visible through a low layer of scud. A pilot who has seen this sort of approach doesn't have to hear a long explanation of how important approach lighting is at the end of an ILS.

Another instrument flight involved ATC giving us a 40 minute delay due to flow control being instituted at Oakland (yes, ATC does indeed issue spur of the moment holding patterns). Puttering back and forth in the holding pattern, a discussion ensued about fuel reserves. If we held for the length of time ATC had specified, then flew to Oakland, it was quite possible we would not have the required IFR fuel reserves for our destination. Teaching scenarios are one thing, but seeing the fuel totalizer tick off gallons remaining while you fly a holding pattern is much more memorable. Especially with 100 low-lead aviation fuel now approaching US$6 a gallon at some Bay Area locations.

I've also discovered some new-to-me, cool features in the G1000 and will post some screen captures just as soon as I get home.

In the mean time, here's a photographic puzzler. What is shown in the photo above, where is it on display, and what makes this particular display unique?