Big Turn, Little Turns, Big Turn

DME arcs can be problematic for infrequent IFR flyers because, like holding patterns, arcs are not that common. A DME arc simply involves flying a circular course around a VOR/DME or VORTAC station (aka the station) at a specified distance, as if the aircraft were attached to the station on a string. Distance Measuring Equipment (DME) onboard the aircraft displays the distance from the station, though an certified GPS receiver can substitute for DME. It's easy to visualize a DME arc if you have a moving map and many late-model GA aircraft with fancy GPS units will fly a DME arc on autopilot while you sit back and watch. Without a moving map, joining an arc and tracking it accurately is more challenging, but it can be an enjoyable challenge. To that end, here are well-tested techniques for flying DME arcs, with or without GPS.

Anatomy of an Arc

The primary protected area around an arc is quite large (4 miles either side), but during a check ride or proficiency check pilots are expected to remain within one mile of the specified arc distance. Approaches incorporating a DME arc will have at least one minimum altitude to maintain, but altitude step-down fixes may be defined at particular radials along the arc.

DME arc Required Obstruction Clearance

Instructors and examiners often use the term right arc for an arc that keeps the station on the right wingtip of the aircraft, or left arc where the station stays on the left. Air traffic controllers usually refer to the general direction from the station where you will fly the arc, such as "arc Southeast." I've see at least one approach chart use the phrase arc clockwise. With calm winds, the station should remain directly off the wingtip. 

Remote, non-radar environments tend to have instrument approaches that use DME arcs because they help air traffic controllers who lack radar to maintain separation between aircraft. I saw a lot of approaches with DME arcs flying in the Caribbean for that very reason. Arcs also allow pilots to fly on their own navigation and get established on an approach course from en route environment. Consider the KLOL VOR/DME-A approach where you could be arriving via the Lovelock 219˚ or 054˚ radial, which happens to correspond to Victor 6.

Get Ready, Get Set ...

From a proficiency standpoint, flying a DME arc demonstrates your ability to plan and maintain orientation. Here are the basic steps.

1. Get established on the correct radial leading to the arc
2. Fly toward the arc
3. Turn approximately 90 degrees onto the arc
4. Maintain orientation as you track the arc
5. Depart the arc on the appropriate radial

More simply, flying a DME arc consists of:

• Big turn
• Several small turns
• One last, big turn

Consider the three basic navigation equipment set-ups found in most GA aircraft:

• Two CDIs (Course Deviation Indicators)
• One HSI (Horizontal Situation Indicator) and one CDI
• One HSI and one RMI (Radio Magnetic Indicator, G1000's call it a bearing pointer)

If you have two separate VOR receivers, set one to navigate to the arc and the other to the fly the radial or course you'll use to exit the arc. Early editions of the FAA's Instrument Flying Handbook cautioned the reader that DME arcs should not be attempted without an RMI/bearing pointer. That wording was removed several years ago.

Tune your DME to the correct station and identify the Morse code id, remembering that these identifiers are broadcast just twice a minute. Beware of DME units that automatically use a frequency tuned on one of your VOR receivers, sometimes called remote channelling, because it's easy to inadvertently get distance information from the wrong station. When possible, consider manually tuning and identify the DME frequency. If you're using an IFR-approved GPS receiver to fly an arc, you have several options covered later.

Fly to the Arc

In the example shown, the aircraft is Southbound, tracking inbound on the CEC 343 radial toward the 11 DME arc. You could set HSI course pointer is set to exit the arc on the I-CEC localizer with the course needle set to 114 degrees and set the #2 CDI is set to fly to navigate around the arc. In this example the aircraft is headed TO the station to join the arc, but other approaches may have you headed FROM the station to join an arc. The first common mistake pilots make is they lose track of the station's position relative to their aircraft. Don't let this happen.

Some folks get all wound up about whether the radial should be at the top or bottom of the CDI. Keep it simple: Set the top of the OBS so it matches the general direction you need to fly to join the arc, in this case 163 degrees. For an HSI, set the course pointer so the arrow generally points in the direction you need to fly.

The Big Turn


Do yourself a big favor and get established accurately on the arc from the get-go. If you blow through the arc by turning early or late, you've made a lot of work for yourself and you're more likely to bust the 1 mile tolerance. It may sound simple, but you need to clearly understand which way you'll be turning initially to join the arc.

Approach charts are oriented North-up and if you're a Track-up person, the chart representation can seem upside-down: There's no shame in rotating your approach chart to a track-up orientation to help you visualize your situation.

With the chart oriented Track-up, it's obvious you want to turn right and keep the station off the left wing. If you're flustered or task-saturated and you simply guess, you have a 50-50 chance of getting it right. You certainly want better odds than 50-50 when flying in the clouds, right?

Many pilots recall a DME arc as being a series of small turns, forgetting that the initial turn onto the arc requires a big turn - roughly a 90 degree turn. You need to turn right, so look at the heading at the three o'clock position of the HSI or CDI. In this case, you'll be turning to a rough heading of 253 degrees. If you have a heading bug, bug that heading.

A 90 degree change in heading at 3 degrees-per-second takes time so you must to lead the arc to account for the distance covered during the big turn. A rule of thumb is to use 5% of your groundspeed as the lead distance. Assuming your ground speed is 120 knots, start turning onto the arc about 0.6 miles before the arc or when the DME reads 11.6 miles. Depending on winds aloft, your groundspeed may differ significantly from your indicated airspeed, so select the groundspeed readout on your DME and pay attention to it. When your DME reads 11.6, make the big turn.

After the big turn, the course pointer points to station

Turn Ten, Twist Ten

Regardless of which way you turn to get on the arc, stay on the arc by making a series of small, strategic changes in heading while adjusting your OBS or HSI to track your progress. Let's say you are using an HSI to fly the arc, twist the OBS so that you just barely have a full-scale needle deflection in the direction you are flying. Not sure which way to twist the course pointer? It's really simple, same side safe:

1. Determine your current heading
2. Locate that heading on the OBS or HSI
3. Twist the OBS or HSI course pointer so the needle deflects on the same side of the CDI as where you found your current heading

Current heading on same side as course deviation bar = Same side safe

Using an RMI/bearing pointer is much simpler: Just adjust your heading to keep the arrow head of the pointer generally aimed at the station.

While you fly the arc, consult your DME to determine your distance and speed relative to the VOR/DME station. By setting the DME unit to ground speed/time-to-station mode, you can strive to see a ground speed (relative to the station) that is below 20 knots or so. That's taxiing speed and you won't get too far off the arc at those speeds.

If you have a heading bug, use it to track your chosen heading and adjust the bug each time you change heading to remain on the arc.

Let's say after joining the arc the DME indicates 11.2 miles. You're outside the arc and need to turn at least 20 degrees toward the station. Don't be afraid to make an aggressive heading change if you are outside the arc. On the other hand, if you joined the arc and the DME indicated 10.5 miles you are slightly inside the arc and that's not a bad place to be. Maintaining the current heading which should eventually take you back onto arc or turn away from the station by just 10 degrees. Wait 5 or 10 seconds and you should see the DME distance increase.

If the DME distance is within 0.1 or 0.2 miles, fly your present heading and wait for the CDI needle to center. Once it does, twist the OBS another 10 degrees, and consider turning the aircraft 10 degrees toward the station. Whether or not you change heading depends on the winds aloft and what the distance readout says.

Stop the Arc, I want to get off ...

To exit the arc on the desired radial or course, you need to make another big turn. Many instrument approaches with DME arcs depict a lead radial to alert you that your exit is approaching. Just like the turn to join the arc, exiting the arc require approximately 90 degrees of heading change.

This bring up the fact that there are four basic DME arc variations:

• Fly TO the station, join the arc, exit the arc flying TO the station.
• Fly TO the station, join the arc, exit the arc flying FROM the station.
• Fly away FROM the station, join the arc, exit the arc flying FROM the station.
• Fly away FROM the station, join the arc, exit the arc flying TO the station.

Additional Challenges

There are many places (the SF Bay Area being one) where there are few published DME arcs. That means a pilot on a check ride or proficiency check may be asked to demonstrate a made-up DME arc with no charted representation. When flying a made-up arc, your examiner or instructor should have specified either a left arc or a right arc, so figure out which way you'll need to turn to keep the station on the left or right side of the aircraft.

A particularly challenging DME arc can be found in the MTN VOR/DME RWY 15 where you arc right to the runway threshold, complying with various step-down fixes as you go. You'd obviously want to fly this arc very accurately. And if you need to fly the missed approach, you get to fly another arc to the missed approach holding waypoint. I've only flown this approach on a simulator, but would welcome the opportunity to try it in a real aircraft.

The Easy Way

If you're using an IFR-approved GPS receiver to fly an arc, here are your options:

• Load the instrument approach defines the arc, specifying the appropriate transition
• Make the VOR/DME station the current waypoint (proceed direct-to)
• G1000 and G530 can display distance to any VOR station that has been tuned

The obvious choice with most late-model GPS receivers is to load the approach with the appropriate arc transisition and let the GPS guide you.

Practice Makes Perfect

The best way to maintain proficiency with DME arcs is to practice in a simulator or in a real aircraft. Like a good crosswind landing, there's a satisfying feeling to flying a good DME arc. Try it, you'll like it.

Jepp, Aeronav and You

Active instrument instructors are frequently asked by their students, "Should I use Jeppesen charts or Aeronav charts?" The easy answer for career-oriented pilots is to use Jeppesen because that's probably what you'll be using once you land your dream flying job. For non-career pilots, the cost-effective answer is Aeronav (at least for the time being). It's fascinating to see pilots become attached to one brand of chart or the other in a Chevy/Ford, Honda/Toyota sort of way. Instrument instructors should ideally be adept at using both types of charts, but even non-instructor pilots may find themselves confronted with a brand of chart with which they aren't accustomed to seeing. Here's an overview of just how different Jepp and Aeronav are, the advantages each has to offer, and some tips for moving back and forth between the two formats.

Name and Version

All approach charts start to look alike when you're tired or stressed, so before briefing an approach it's a good idea to first verify the name and version. Both Jepp and Aeronav put the approach name in the upper right corner, but Aeronav also puts the same information in the lower right corner. Jepp puts the city/state in the upper left corner while Aeronav uses the upper and lower right corners. Locating the city and state on a chart may seem unimportant, but it's a surefire way to be sure you have the right chart given the tradition of assigning multiple names to an airport (e.g. John Wayne/Santa Ana/Orange County or Charles M. Shultz/Sonoma County/Santa Rosa).

Jeppesen Naming Conventions

Aeronav Naming Conventions

The airport identifier on Jepp charts is in the upper left corner and includes both the FAA and ICAO format. Aeronav charts show the same information (sans the ICAO identifier) in the right corner. Aeronav really needs to standardize on ICAO format for airports: It would certainly remove the common confusion between GPS waypoints representing an airport and those representing a VOR with the same name as the airport.

Flying an approach with an out-of-date chart is ... well, stupid. Jepp puts the revision and an optional effective date on the top of the chart in day-month-year format. This is inherently problematic because by themselves, these dates are meaningless. They tell you when the chart you are reading became effective, but they don't tell you if a more current version is available. The assumption is that you've applied any Jepp updates that have been released and while this works fine for electronic charts, you know what happens when you assume ... Jepp also has a proprietary indexing schema that you can memorize if you wish and they may put an amendment number on the lower left edge and the reason for the revision at the bottom of the plate. This stuff may be interesting, but it doesn't really answer the question "Is this chart the current one?"

Jepp Revision and Effective Dates

Aeronav prints a valid date range for the chart on both the left and right edge of the plan view. If today's date isn't in the range shown on the chart, the chart is out of date. Simple, straightforward, and (dare I say it?) fool proof.

Aeronav Valid Dates

Briefing Information

The BriefingStrip™ was a Jeppesen innovation designed to provide the essential information for the approach in a consistent format. Many pilots begin briefing an approach by reading this strip, though I find this technique can overlook some important information. A few years back, the Aeronav (nee NACO) folks began incorporating a similar feature they named Pilot Briefing Information. Whether you call them strips or information, they mostly contain the same stuff in a slightly different order.

Jepp Briefing Strip™

Aeronav Pilot Briefing Information

Jeppesen's Briefing Strip starts with the radio communication frequencies, then the WAAS channel or navaid frequency and approach course. Aeronav puts the WAAS channel or navaid frequency and the approach course first. Jepp includes the minimum altitude at the final approach fix and the minimum descent altitude or decision altitude. The missed approach descriptions are virtually identical. Aeronav charts display the minimum safe altitudes on the plan view. Jepp puts them in the briefing strip, except for RNAV approaches that have a terminal arrival area where Jepp also shows the MSA sectors on the plan view: There's not a lot of difference between the two products, until you consider the Notes section.

Noteworthy

Jepp, being an internationally oriented product, starts the Notes section with the units used for the altimeter setting and the transition altitude (where the flight levels start). In the US this information is superfluous, but outside the US it is indeed important. Jeppesen prefixes each note with a number, which increases readability.

Jepp Notes Format

Aeronav charts add an inverse T to indicate when non-standard takeoff minima are present or to indicate that a charted departure procedure is available for the airport.

The inverse A indicates when an approach has non-standard alternate minima. And to be consistently inconsistent, the N/A suffix can be used with the inverse A to indicate that an airport is not authorized for filing as an alternate. Jepp buries the fact that the airport can't be filed as an alternate on the separate airport info page, which is also where you'll find the airport's obstacle departure procedure. Not too handy, but it kinda makes sense.

Jepp Airport Diagram, Alternate and ODP info

Aeronav may include an inverse W on RNAV approaches to indicate that WAAS NOTAM service is not available for an airport. Translation? WAAS may not be available at all times, you may only get LNAV precision, and there won't be any WAAS service NOTAM to warn you during pre-flight planning.

Consistencies between both brands of charts in the Notes include (but are not limited to):

• Procedure is not authorized at night
• Visibility reduction by helicopters not authorized
• Required equipment or when simultaneous reception of two navaids is required
• Alternate altimeter settings
• Approach course out of alignment with runway
• Visual glide slope and descent angle or electronic glide slope not coincident
• Conditions under which a visual descent point is not authorized

Pilot-Controlled Lighting:

• Jepp lists lighting limitations in the notes section
• Aeronav depicts it with an inverse L in the communications section

Circling Restrictions:

• Aeronav puts circling restrictions in the Notes
• Jepp puts them in the minima section, which makes a whole lot more sense

One maddening convention both charts follow is that if a different airport's surface weather is to be used, they don't provide that ATIS, ASOS, or AWOS frequency. In an age of electronic cross-referencing, this is simply criminal.

Aeronav uses the Notes section to tell you how many feet to add to the DA or MDA when using a different altimeter setting, but Jepp courteously does the math for you in the minima section.

Jepp Circling Restrictions and Minima with Alternate Alitimeter Setting

Plan View

Both charts have a North-up plan view depicting information a pilot needs to get established on a segment of the approach. Relevant obstructions are depicted on both types of charts. Note that there seem to be some discrepancies in obstruction heights on the Jepp and Aeronav charts.

Jeppesen Plan View

The highest obstruction are designated with a bold black arrow on Jepp charts and with a bold, black dot on Aeronav charts. One advantage of Jepp charts is that the Morse code for all navaids is shown, but Aeronav just gives you the navaid identifier.

Aeronav Plan View, missing some Morse Code ...

Profile View

Once established on a segment of the approach, the profile view depicts approach fixes (waypoints) and crossing restrictions for each fix. Both charts follow the convention of showing the profile from right-to left for final approach courses between 360 and 179 degrees, otherwise the profile moves from left-to-right. Given that the English language is written from left-to-right and English is the official language of aviation, changing the flow of the profile view to fit the magnetic course has always seemed a bit strange to me. Whatever ...

Neither chart product shows the profile view to scale. Aeronav just shows a diagonal line for each segment. Aeronav depicts glide slope intercept with a lightning bolt arrow and in this example, puts the graphical depiction of the missed approach procedure in a more logical and intuitive location since it is near the graphical depiction of the missed approach point on the profile view. And for those occasions when you need to conduct a circling approach, the inset map is a very handy feature.

Aeronav Profile View and Minima Section

Jeppesen clearly depicts step-downs with a level-off. Crossing restrictions are shown above the profile line, which is much more user friendly. The graphical depiction of the missed approach is located below the profile view, which is less intuitive. And when multiple minima are possible, Jepp does a thorough job of depicting those on the profile view.

Jeppesen Profile View and Minima Section

Approach Minima

Another area where these products differ is in the minima section. Jepp clearly depicts the changes in the minima when approach lighting or other components are out-of-service. With Aeronav, you must reference the Inop Components table in the front of the approach booklet - This is a really bad arrangement and one that most GA pilots hope they seldom have to deal with. Having to locate the Inop Components table when using electronic charts is B-A-D for single-pilot operations.

Jepp provides a wider range of speeds, timing from the FAF to the MAP (if appropriate), and descent rates than the Aeronav counterpart. Jepp will also depict the approach lighting that is installed, if any.

STARs and SIDs

Minor differences exist in charted arrival and departure procedures, but they aren't that big of a deal. Jepp scores some extra points by putting crossing altitude expectations next to the fix on the plan view while Aeronav buries it in the narrative.

Airport Diagrams

Aeronav provides a single airport diagram. Jepp may provide several pages of information in addition to the airport diagram, such as low-visibility taxi routes. On the airport diagram, Jepp may include Lat/Long for various parking gates, which is helpful to airline flight crews. Both products depict Hot Spots - areas where pilots historically have become confused or where runway incursions have occurred.

Extra Cost Justified?

Jeppesen has claimed that the extra cost for their product is a result of the quality control/assurance functions they perform, but the claim seems a bit hollow given how Jepp was tardy in including current RNAV approach charts for several smaller airports in California. Most recently, Jepp published an ASOS frequency for the Rio Vista airport before it was certified. I pointed this out and they removed the ASOS from the two approach charts. Then, when the ASOS was officially put into service, Jepp was one cycle behind in adding the frequency back to the charts. On several occasions I've notified Jepp about errors in their charts, but they never told me I was part of their QA team.

For their part, Aeronav makes their share of mistakes and does some weird things, too. In the case of the Rio Vista approaches, even though the ASOS frequency is published on the chart, the notes tell you to use either the Vacaville or Concord surface weather (and of course they don't give you that frequency). I've also found errors in Aeronav charts and like the Jepp folks, they are generally very receptive to feedback. After a jet blast encounter with a wayward biz jet crew a few months back, I suggested to the Aeronav folks that the depiction of one hot spot on the Oakland airport diagram wasn't in the best location. Lo and behold, they listened and changed it!

I've said it before and I'll say it again: Jeppesen is much more expensive than Aeronav. Of course, if/when Aeronav products pricing structure is modified, this could change.

Keeping it All Straight

If you're an active instrument instructor or a pilot who needs to occasionally use both types of charts, you've got your hands full. Your best bet is to practice using both types of charts on a regular basis. And you don't need to be in a real aircraft to practice: You can fly any approach in your arm chair or in a simulator for little or no cost. It's certain that I haven't covered all the differences, advantages and disadvantages of each brand of chart product. If you think I have missed something important or have your own tips and tricks to share, I'm all ears.

Sweat the Small Stuff

Papers pile up on your desk, stuff accumulates in your garage, weeds grow in your garden, and you reach a point where action must be taken. Call it cleaning house or a garage sale, nothing beats finally clearing away all the junk, reorganizing, and simplifying. Think about complexity in aviation, specifically under Instrument Flight Rules, and it's easy to see some house cleaning is in order. Needless complexity in aircraft equipment and instrument procedures has increased errors, gaffes, and worse on the part of controllers and pilots alike. Both the FAA and GA manufacturers could take simple steps to clean things up and here is a list of just a few of the needed fixes and improvements.


By Any Other Name ...

The FAA Instrument Approach Procedures Division has done a great job of creating a plethora of RNAV approaches with vertical guidance. Kudos! Now it's time to tackle a much simpler problem: Instrument approach procedure names. They have become needlessly convoluted and naming conventions are important because pilots and controllers say those names over the radio, thousands of times a day. Pilots have to look-up instrument approaches, sorting through long lists of similarly named procedures. Add to the mix similarly named approaches to parallel runways and it's obvious that selecting the wrong approach by mistake could have serious repercussions.

Controllers and pilots can often be heard saying something like "Cleared RNAV GPS 32 approach" when it should be simply "Cleared RNAV 32 approach." Many pilots and controllers apparently don't realize that approach title items that appear in parenthesis are not to be used when referring to the approach. Who came up with that convention? Bet it wasn't a pilot or a controller.

Complicated, dumb naming conventions add no value, but they do create confusion and extra workload for all concerned. Consider this subset of the RNAV approaches at my home airport:

• KOAK RNAV (GPS) Y RWY 27R
• KOAK RNAV (RNP) Z RWY 27R
• KOAK RNAV (GPS) Y RWY 27L
• KOAK RNAV (RNP) Z RWY 27L

How about a naming scheme where RNAV would refer to approaches for use with appropriate area navigation or GPS, RNP would refer to approaches with curved paths reserved for authorized aircraft and aircrew (i.e. not most GA aircraft)? And lose the stuff in parenthesis fer cryin' out loud! The list of KOAK approaches would then read as follows:

• KOAK RNAV RWY 27R
• KOAK RNAV RWY 27L
• KOAK RNP RWY 27L
• KOAK RNP RWY 27R

That would make it easier (and safer) for everyone, now wouldn't it?

Smart Vectors-To-Final

Adhering to crossing restrictions at step-down fixes leading to an ILS is important because early interception of the glideslope does not necessarily guarantee compliance with altitude crossing restrictions outside the final approach fix (FAF). This is where Garmin's implementation of Vectors-To-Final (VTF) for instrument approaches comes under scrutiny.

Let's see, 5 plus 2.3 plus 2 = ...

Since the late 1990s, when the 430/530 units were first introduced, activating an approach with VTF has remained virtually unchanged. VTF causes any step-down fixes outside the FAF to disappear, the current waypoint becomes the FAF, and the only distance displayed is the distance to the FAF. To locate step-down fixes before the FAF, the pilot must perform some interesting mental math. This is particularly vexing because when a pilot hears a controller say "fly heading 210, vectors ILS 27 right" and they see an option named "Vectors-to-final," they naturally assume that's the option to choose. The standard operating procedure is actually to never use VTF on approaches with step-down fixes outside the FAF, even if the controller says "vectors RNAV 28 left approach."

The vectors-to-final option should result in the GPS receiver figuring out where the aircraft has intercepted the approach course and all fixes outside the FAF should be depicted. If the current behavior is required by the relevant Technical Standard Order (TSO), then Garmin and the FAA need to work to change those TSOs. Touch screens interfaces on GPS receivers are great, but pilots have been waiting for a fix for VTF behavior for over a decade. This isn't rocket science.

Alternate Airports

With the exception of the discontinued CNX 80, Garmin GPS receivers do not provide the ability to define an alternate airport as part of a programmed flight plan. In fact, the flight plan behavior of the Garmin units is so convoluted that it would take an entire blog post to describe the work-arounds pilots have to do when navigating to their alternate after a missed approach. Pilots don't need increased workload during critical phases of flight. Hello? Garmin?

Required Equipment

When pilots and instructors sit around the hangar and debate the possible reasons why ADF is required on an approach, something is wrong. An instrument approach needs to be clear so that it can be accurately flown. In the evolving world of RNAV, the convention of encoding the equipment required for an approach in the procedure name is quickly breaking down. So here's some heresy: The design details that require certain equipment for an approach should be opaque to pilots.

Pilots don't need to know why, we just need to know what. The FAA needs to list the required equipment (along with other  restrictions) on the plan view, in plain view, and in a font big enough that pilots can read. Pilots shouldn't have to theorize what stuff they need in the panel to legally fly a particular approach.

User-defined Holding Patterns

The CNX 80 allowed the pilot to program an ad hoc holding pattern and then allowed the GPS and autopilot to fly that holding pattern. The CNX80 has been discontinued and follow-on models still don't seem to have the user-defined hold feature. It's great that Garmin is working on voice-controlled avionics, but user-defined holding patterns is a basic feature that's still missing. Again beating up on Garmin, but they make it so easy. 

PT Required or No PT?

A decade ago it appeared RNAV approaches would all be designed with Terminal Arrival Areas (TAA) that would simplify the delivery of approach clearances, reduce workload on controllers, and allow pilots to navigate on their own using RNAV. While some older RNAV approaches do provide minimum safe altitude information by TAA sectors and explicitly include the No PT notation for entire TAA sectors, the TAA seems to have fallen out of favor and isn't included in many of the new RNAV approaches. Perhaps this is a cost-saving maneuver, but it sets up a bad situation with regard to procedure turns.

You were just cleared direct to an Initial Approach Fix on an RNAV approach with a 30 degree intercept to the approach course, but you're not on a transition that tells you the Hold-In-Lieu-of-Procedure turn is not required (NoPT). If the controller doesn't say "Cleared straight in RNAV ..." you're expected to fly once around the hold. Of course if the controller simply forgot to specify "straight in" and you fly the hold, you'll probably get yelled at or worse (cf. Limitation on Procedure Turns). The best advice for pilots in the situation is to query the controller if they don't get a straight-in clearance.

Perhaps depicting MSA sectors is not feasible for technical reasons, still the FAA should find a way to clearly specify when a procedure turn on an approach is required and when it isn't.

Which Weather?

Approach procedures into some non-towered airports specify that you should use the surface weather for a nearby airport. In the current age of electronic information, why can't the FAA (and by extension, Jeppesen) include the frequency for that airport's surface weather? This sort of simple cross-referencing is what computers are good at.

Digital Charts

The days of individual paper chart purchases are quickly fading and the production of these charts needs to be modernized. VFR and IFR charts need to be produced in a way that allows seamless electronic display. Many EFB users may not realize it, but there is significant effort going on behind the scenes to stitch together these charts for EFB display. And while we're at it, geo-referencing on instrument approach charts should not require significant third-party effort and cost to provide. The times they are a changin' and the Aeronav folks have been working hard to keep up with those changes. Let's hope their chart products continue to be modernized.

Jeppesen has had over a year to get their digital chart act together for the iPad, but geo-referenced en route and approach charts are still missing in action. One assumes that once these features are finally available, they still will cost you your other arm and/or leg.

Digital Documents

Cessna/Textron has probably made more training aircraft than any other manufacturer in history, but you can't get PDFs of their pilot information manuals. Diamond, Cirrus, and even Garmin provide important documents for download as PDFs. Given the rapid acceptance of electronic tablets like the iPad, Cessna needs to get with the program.

And speaking of Cessna, ever try to figure out if your aircraft's Approved Flight Manual and all of its supplements are up to date? Good luck to you because it's a nightmare!

Anyone Listening?

You may have ideas for simple fixes that would result in big payoffs for little investment, but you may ask "What's the use? Is anyone in a position to make the changes actually paying attention?" Before glossing over the idea that seemingly trivial improvements really can have a tremendous impact on any system, take a few minutes to watch Rory Sutherland's TED talk on the subject. The important points are toward the end, but it may just change the way you look at small stuff.

Sound of Ten Thousand "D'ohs!"

NORCAL: Cessna 123, verify you're direct ALTAM at this time?
Cessna 123: Not yet, we're still wrestling with our GPS ...

Never shy to point out the shortcomings in Garmin's 430/530/G1000 user interfaces, I'll admit I'm all excited to see the announcement of the GTN 650 (MSRP $11,495) and GTN 750 (MSRP $16,995) products. The 430/530/G1000 were, in a sense, a victim of their own success. So many units were sold that the user interface, as bad as it was, became something of a standard. Not unlike Microsoft Word, many of us got used to the dance of cursor-mode-big-knob-little-knob-enter and tended to forget how bad the user interface (UI) really was. To their credit, Garmin has done the sensible thing: Confronted with a bad UI that suffers from the Tyranny of the Installed Base, they started over from scratch with a touch-screen interface. While I've yet to actually handle one of these units, a lot can be gleaned from the videos that have been released and the information at Garmin's website.

Same Market, New Interface

The GTN 750 and 650 clearly target the aging GNS 530W and 430W, both in size and features. The new units provide the same basic stuff for aircraft owners and operators who want to freshen up their panels: Communication transceiver along with a WAAS GPS and VOR receiver as well as a moving map with some additional features.

Both units can provide an interface to remotely control a Garmin GTX mode C or mode S transponder. The GTN 750 can also control a remote audio panel. These interfaces to remote devices have the advantage of reducing the panel footprint, but the downside is that they can increase the complexity of the user interface. When a GTN unit becomes the single lens through which you access other important functions, the advantage of a smaller panel footprint doesn't look quite as attractive.

Why a different keypad? Why not one style of keypad with the 8 & 9 disabled for transponder use?

Out with the Old

A recurring problem with avionics designs is that, in an effort to reduce production costs, manufacturers are motivated to limit the number of buttons and knobs. With fewer knob and buttons, the UI designers must overload the function of those knobs and buttons: Depending on the state of the device (which is not always obvious), a knob or button will do different things. Overloading creates user interface complexity because the user must be cognizant of the device's state (which is not always obvious). One only has to witness a 100 different pilots experience the same UI frustration at high workload moments to know that overloading and convoluted, deep menu structures are B A D.

Manufacturers next tried to overcome the shortcomings in overloading by using softkeys - physical buttons whose displayed function changed depending on state of the device. The success of this was limited in the G1000, as an example, because different modes take control of different softkeys and the precedence is seldom clear. Try adjusting the flight plan on the MFD while the other pilot is using the lean-assist function and you'll get the feeling that there were different groups of programmers working on the different G1000 areas: They don't seem to have worked that closely with one another.

No Place like HOME


At the center of the new GTN units is a capacitive, touch-sensitive screen. There are just two knobs, two physical buttons, and an SD card slot (presumably for terrain and aviation databases). Grip points are provided on the sides and bottom of each unit so you can steady your hand in turbulence. And there are suggestions (but no details yet) on voice control features in the future, but for now the UI flexibility comes from having a touch-screen.

Both units clearly display the com and nav frequencies at the top of the screen. The active frequencies are at the top with the standby frequencies underneath. From the demonstrations it appears you swap the active and standby frequencies by tapping on the active frequency, which seems a bit counter-intuitive. Tapping on either standby frequency causes a pop-up a keypad to appear in the middle of the screen and you just tap in the new frequency. I hope there's an option for eliminating having to enter the leading "1" since all VHF nav and com frequencies are in the 1##.### range.

Different number keypad than for the transponder. Why?

The HOME button allows you to return to the main screen which is the starting point for a refreshingly simple and relatively flat menu structure. Unlike the subtle context indications in the 430/530/G1000, the HOME screen gives you a clear idea of the top level of functions. To access a function, just tap on the icon.


A dedicated Direct-To button is provided and this is a really, really good design choice because pilots, depending on your perspective, become creatures of habit or slaves to their devices.  In a high workload moment, there are few things worse than having an important button buried in a row of not-so-important buttons.

The knob in the upper left corner adjusts the volume and squelch for the com radio while the knob at the bottom allows you to change either the Nav or Com frequency. This a shame because the location of the bottom knob violates a basic UI concept: Whenever possible, physical knobs and buttons should be located directly adjacent to the display item they affect. If you need proof, witness someone trying to adjust the barometric pressure setting on a G1000 at a high workload moment.

Having a physical frequency selection knob means there are multiple ways to change frequencies. Alternate ways to accomplish the same task isn't necessarily bad, but it is something that earlier Garmin interfaces suffered from because some of the methods were Easter Eggs. Examples in Garmin's older interface designs? Pressing Direct-To once provides one feature while pressing it twice provides another feature. Or being transported into a hidden set of options when turning the small knob counter-clockwise (instead of clockwise) while in insert mode. If describing a user interface in words is this complicated, something in the design isn't right.

At the bottom of the screen are some icons for displaying system messages as well as a relatively small status line that tells you the GPS course sensitivity as well as which NAV source (GPS or VOR) is being displayed on the CDI or HSI.

Map View

The map view is similar to what we've become used to with the G1000 and one suspects it will offer similar options for North- or Track-Up, a compass rose ring around the aircraft, a fuel endurance ring. In one of the demonstration videos, the refresh rate of the map looked a bit slow. Not sure if this was an issue of the screen refresh rate interacting with the video camera's sampling rate or a limitation of the GTN's processor speed. I hope it's the former and not the latter.

Terrain, Traffic, Weather, Music, Intercom

The terrain features look pretty nice. And with the appropriate remote hardware installed, both units give you access to traffic and XM weather. Presumably TIS traffic data is available from a mode S transponder (for as long as the FAA radar sites continue to support it), from a dedicated transponder-based TAS system, or from the much vaunted (but yet-to-be-widespread) ADS-B facility that NextGen is supposed to have. If you choose the XM subscription that includes entertainment radio, you can access that, too.

One of the shortcomings of using the GTN 750 to provide an audio panel or other interface is that you lose the moving map when you access one of these features. The simple act of adjusting the pilot or co-pilot intercom volume will temporarily hide other features, like the moving map display with traffic, weather, or terrain data. It also appears to be a single point of failure: Lose the touch screen and you'll be hard pressed to change your transponder code, adjust your intercom volume, and so on.

One assumes that if there's an imminent traffic or terrain threat, that display will override any trivial function you might be performing. Hard to say without actually handling one of these units in flight.

Terminal Procedures and Taxiway Diagrams

Aeronav and Jeppesen charts can be displayed on the GTN 750, but the size is pretty small and requires scrolling around. Geo-referencing is offered, though the subscription costs tend to be high and much more cost-effective options are available on the iPad or other off-the-shelf consumer devices.

Crux of the Matter

With all GPS designs, the ease with which one can enter and modify a flight plan is what makes or breaks a user interface design. While there are many pilots out there who just fly VFR and only use Direct-To, there are IFR pilots who'll need to enter a sequence of waypoints that match the clearance they just got from ATC.

Assuming you have a steady flight path, the GTN 750 lets you enter waypoints into your flight plan by simply tapping on their representation on the moving map. You can also enter waypoint using a pop-up keypad. No more singing the alphabet as you scroll through adding a waypoint with the big-knob-small-knob interface. Last but not least, you can drag an existing flight plan course line on the map to add a new waypoint to the flight plan. I'll have to use this in person before I can say whether it rocks or is just more usable than the old big-knob-little-knob interface, but these flight plan features alone may be worth the price of admission.

With the GTN 650's small screen, there's an odd kludgey selection process. Bummer about that ...

Grace Under Pressure?

My initial research hasn't turned up any examples of  loading procedures and I'm particularly curious to see if the vectors-to-final behavior has been improved.

Simulator, Please!

One of the really smart things that Garmin did with the 430/530 was they made a PC-based simulator available to download at no charge. It is my contention that having a simulator to practice with was one of the driving forces behind pilots' and aircraft owners' widespread acceptance of the 430/530 series. As of this writing there is no such simulator available for the GTN series. Surely Garmin will see that it is in everyone's best interest to provide one. Soon.

A New Leaf

As to whether or not these units are a good deal or attractively priced, I'll leave that assessment to the aircraft owners and other pundits out there. After all, I'm but a humble, professional flight instructor and freelance writer who rarely has more than a couple of coins to rub together and the mere prospect of owning an aircraft is beyond my ken. Garmin doesn't invite me to their media events, so I've taken an academic yet honest approach in this review because I hope this is what my readers have come to expect. I'd certainly like to fly one of these units in the near future, perhaps even train the next wave of instrument pilots to use them. Who knows, maybe the introduction of the GTN series will transform the sound of 10,000 pilots crying D'oh! to the sound of a single Ommmmm ...

ForeFlight Geo-referencing and OpSpec Approval

Don't Use for Navigation

Even if you're an old school pilot who secretly thinks the road to hell is what's displayed on a moving map, I'll still wager that you'll find geo-referenced approach charts and airport diagrams compelling once you see them in action. ForeFlight's new geo-referencing feature is the result of licensing of original technology developed by Seattle Avionics. This option increases the yearly ForeFlight subscription from $74.95 to $149.99, but you can also buy subscriptions for more than one iPad or inquire about a corporate subscription plan. And while a Jeppesen has generated a lot of buzz by announcing OpSpec approval for at least one operator using their iPad app, you should know that the same approval for ForeFlight Mobile HD (FFM) on the iPad has also been accomplished. More on that later.

Required Ingredients

To use ForeFlight's geo-referencing feature, you'll need two ingredients. You'll need to pay the additional fee and you must have some sort of GPS. If the additional fee seems costly, consider this: The annual FFM subscription includes all of the Aeronav charts and procedures one could want for a cost that is only slightly more that what you'd pay for a Jeppesen Mobile TC subscription for California only (sans geo-referencing, by the way). That makes FFM a pretty good value, if you ask me.

The built-in GPS-A found in the 3G iPad may work okay on the ground, then again it may not. In the air, relying on the built-in GPS-A would be a pretty dicey plan. For my testing, I used the GNS 5870 bluetooth GPS which I've been flying with for several weeks now. To date the GNS 5870 has performed flawlessly: It has achieved satellite lock reliably and quickly and the data it provides to ForeFlight Mobile HD has basically matched the GPS data I've seen displayed on panel-mounted GPS receivers like the Garmin G1000, 530W and King KLN 94. I certainly don't sanction relying on a bluetooth GPS for primary navigation, but it's a nice back-up to have on board.

You are ... Here

The geo-referencing in FFM is provide on approach procedures and airport diagrams only. When this feature is available, you'll see a light blue box drawn around the plan view on the approach chart or around the airport diagram. Once you are within the area being covered by the chart, your location will be shown with a little blue airplane surrounded a pulsating animation.

If you want to see your groundspeed, track and other GPS-derived information, you'll need to go into the settings and disable the Auto-Hide Toolbar option. Otherwise, the navigation tab will disappear after a few seconds and you'll have to tap on the center of the chart to get it back. Displaying navigation information during an approach is overkill if you have a panel-mount GPS, but on the taxiway diagrams it provides a good indication if you are taxiing too fast (a bad habit that many pilots have).

There are some accuracy limits to the taxiway diagrams. On a couple of occasions I noticed the airplane's position was being shown slightly off the taxiway we were actually on, but most of the time it was spot on.

On the Main Ramp, but showing "in the dirt"

In the air, I found the accuracy with the GNS 5870 was quite good. In particular, the map gives you a good idea when you're about to intercept an approach while being vectored and helps you maintain situational awareness when flying a full approach with a procedure turn or hold-in-lieu-of-procedure-turn. I even tried it out on a circle-to-land approach: I zoomed in on the approach chart, saw the aircraft's position as being abeam the touchdown zone, and the position was spot on.

Right downwind, abeam RWY 20

One minor gripe is that when you zoom in on a geo-referenced chart, the blue airplane that represents your position is not scaled to match the new chart scale. The result is that the more you zoom in, the smaller the airplane symbol appears.

To Buy or Not to Buy

If you have a panel-mounted GPS and are on a tight budget, you can probably forego the geo-referenced approach chart and taxiway option in FFM. But for not a lot of extra dough, I find this option to be useful enhancement to safety and situational awareness. You'll also need to invest in either a bluetooth GPS like the GNS 5870 MFI Bluetooth GPS Receiver or something like the Bad Elf GPS Receiver.

Getting Approved

Operators who want to get approval to use an iPad solution from their FAA Flight Standards District Office may be interested to know that Cutter Flight Management, Inc. has received authorization to use the iPad with ForeFlight Mobile HD and Jeppesen Mobile TC. Cutter will use ForeFlight to provide domestic en route charts and terminal procedures with Jeppesen providing terminal procedures for international operations. The process for operators gaining OpSpec approval for an EFB is detailed in AC 120-76A, the EFB Job Aid, and in Order 8900.1, volume 4, Chapter 15, Section 1: Electronic Flight Bag Operational Authorization Process.

The EFB evaluation process usually takes about six months with an additional two months for the approval process. Currently, operators must demonstrate the iPad can withstand rapid decompression and that the device doesn't interfere with aircraft avionics and systems. Seeing it has already been demonstrated that the iPad meets these requirements, it seems odd that each individual operator must go through this. Operators must also develop a training program for their flight crews in how to use the device and the EFB software.

Less Paper, More Bytes

It looks like the dream of a paperless cockpit continues to evolve and the rate of acceptance of EFBs in the cockpit is on the rise. In the coming months it should become clear if EFBs really do reduce the time, effort, and expense associated with maintaining navigational charts and procedures. And just imagine how much lighter all those pilot's brain bags will be.

U-Turns

My usual goal is avoid anything to do with aviation on my day off, but I feel compelled to help out today because I’ve learned something important over the years: Everything in aviation is connected - people, planes, airports, weather. Today’s short flight is to ferry an aircraft to a nearby airport for it’s 50-hour oil change and to have some squawks (minor problems) addressed. I haven’t flown this aircraft in a while, but things can change in a heartbeat. I never know when my teaching schedule could make me dependent on this particular plane. Obviously others are flying this plane, otherwise it wouldn’t need an oil change and the best time to wrench on a plane is when the weather prevents it from flying anyway. Unnecessary down time causes everyone to lose and the simple act of ferrying this plane will help the owner, the operator, other instructors, other pilots, and ultimately myself. The way I look at it, aviation is just a really big family.

For the last six weeks the weather has been nothing short of spectacular, better than many summer days. Today the conditions just turned decidedly winter-like with the first of what promises to be a series of cold fronts. The surface winds are out of the Southeast in the vicinity of 15 knots with gusts up to 30 knots, the ceilings and visibility near my house are low with light rain and mist, but the departure and arrival airports are still reporting weather consistent with visual flight rules (VFR). Experience tells me the conditions near my house will eventually spread to the Southeast, engulfing both airports, making them switch to the more complicated and time-consuming instrument flight rules (IFR). It only takes a little imagination to see that if I begin the flight soon, it will be a short, simple affair under VFR. A later departure will make the flight more complicated and time-consuming. I hope for the simple version, but because I know life is complicated I also file an IFR flight plan before leaving the house.

With traffic, I’ll need about 40 minutes to complete the 15 mile drive to the airport. There are a bunch of non-aviation chores to be done on my day off that I’m hoping to do first. And since the ferry flight will be a one way trip, I coordinate a ride back to my car with a friend. Glancing at the time, I do the mental math, consider time to dispatch and preflight the plane, add an extra 30 minutes, and decide on a departure time of noon. On the way, Google maps on my iPhone shows slow freeway traffic. Only after experiencing the slow-and-go firsthand does the cause become clear: Two blocked lanes where CalTrans is sweeping the median. 20 minutes of my 30 minute fudge factor are now gone.

During the dispatch and preflight, I take note of the minor discrepancies other pilots have reported. More delays slowly eat into the remaining 10 minutes of my fudge factor before I have the engine started. Then I discover a minor problem with the number two radio that was previously unreported. Hey, it’s not my fault! As a freight dog friend of mine used to say, “I don’t break ‘em, I just fly ‘em.”

The delays have compounded and the weather is deteriorating rapidly. Low ceilings and rain are creeping in from the Northwest, but the Bay Area is on the Southeast plan and that will help my cause: I’ll be headed directly to my destination right after takeoff. What doesn’t help is that the ground control frequency is busy and the controller seems distracted. I call for taxi and am told to hold my position. I hear two landing bizjets inform the tower they broke out on the approach at 500 feet. The current Automated Terminal Information Service (the airport’s weather report) was reporting an overcast ceiling at 2500 feet. The ATIS obviously need to be updated and that may explain the distracted controller. As I sit and wait, I can see my VFR plans fading rapidly. After another two minutes of waiting I throw in the towel, switch to clearance delivery and request an IFR clearance. I’m glad I filed that IFR flight plan. Calling ground control again with an IFR clearance, I get immediate taxi instructions.

The last card I may be able to play is to depart IFR and hope to remain out of the clouds long enough to see the nearby destination airport. That could allow me to call the field in sight and still proceed visually to the airport. That plan looks doubtful as I hit the clouds at 500 feet after takeoff and aside from brief glimpses of the ground, I can’t see the destination airport.

Looking on the bright side, I’ll get a rare, solo IFR flight in a nice, steam gauge aircraft. A change of pace is always good. The ride gets a bit bumpy, then I break out between cloud layers for a few moments. Further to the East the conditions are still VFR. I can see the Livermore airport for a few minutes before I’m turned back into the clouds toward my destination.

All the instrument approaches to my destination are to the West-facing runways. The strong, gusty surface winds dictate a circle to the opposite, East-facing runway once I enter visual conditions. In essence, the entire flight has been a very large U-turn in the sky, followed by another U-turn before landing. This flight is a good illustration of how IFR flights can be much more complicated and time-consuming that a short VFR hop. Southeast, three miles out on the approach I see the destination airport and the slow-moving wall of precipitation closing in from the Northwest.

The tower controller’s instructions are to circle to the South and I’m cleared to land on the East-facing runway. Flying the downwind leg, parallel to the runway, requires about a 20 degree wind correction angle to the left to keep the wind from pushing me over the runway. Though I’m in visual conditions, I’m careful to not descend below the minimum circling altitude until I’m on final approach to the runway. My base turn is just clear of the rainy goo that is about to engulf the airport.

Completing the final U-turn and aligned with runway, the 20 degree wind correction angle is now to the left. Unprompted, the tower controller informs me the surface winds are out of the South, gusting to around 25 knots. Flaps 30 and this will be a good crosswind component. The little gray cells are fully engaged as I focus on the white paint on the runway pavement. The aiming point on the runway appears to move up the windshield and the plane is bounced about. A little wind shear, but my left hand has unconsciously moved the throttle in to increase engine power. A few seconds later, the aiming point is moving down the windshield and I reduce power. This dance continues until the aircraft is right over the runway pavement.

Tracking right over the centerline, the nose is still pointed to the right to compensate for the wind. Slowly move the throttle toward idle, the plane sinks to the pavement, just ease in left rudder to align the nose with the centerline, simultaneously turning the yoke to the right to offset the wind. The right main wheel touches first, lightly, and time seems to stop with the plane balanced on one wheel. Gradually the left main wheel touches down, the nose wheel follows, and it’s time to turn the yoke all the way to the right, retract the flaps and gently start braking.

Taxing clear of the runway, the ground controller clears me to taxi and there’s a moment to reflect. Few things in life as satisfying as a well-executed crosswind landing, but that’s just icing on the cake. I’ve hit the trifecta - a nice solo flight, an instrument approach, and I’ve done my part to keep my aviation community running smoothly. Who knows what tomorrow will bring, but today the shortest distance between two points consisted of two U-turns.