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.

Surprise, Surprise

The concept of automation surprise has been around for years in the large aircraft world and now it's part of the GA aircraft that you are flying or might soon be flying. Automation surprise occurs when a system, such as a GPS receiver and/or autopilot, does something the pilot neither expected nor intended. The result is that the aircraft deviates from an assigned heading, route, altitude, or approach path and the pilot may lose situation awareness, too. Actually, it's the pilot-in-command who is considered to have deviated, not the plane or it's systems and blaming the machine is an argument that's probably not going to hold water. With all the technically-advanced GA aircraft out there, automation surprise is now something that GA pilots must understand and be ready to handle.

While I don't pretend to be a human factors expert, I've both witnessed and been on the receiving end of automation surprise on several occasions. Most of the surprises I've seen in GA aircraft resulted from the pilot making mode errors - not fully understanding the consequences of their knob twisting and button pushing. Yet I have also seen deviations result from equipment failures and even from shortcomings in the design of an instrument procedure. There can be a seemingly endless number of ways for things to go wrong in a complex, automated environment and while we may want to never make any errors, mistakes are going to happen. I'll provide just a few examples of how things can get out of hand when technology is busy making the pilot's job easier and what you can do when the magic turns evil.

Operator Error
Here's a mistake I've witnessed many pilots make with the two-axis KAP-140. ATC instructs "... climb and maintain 7000." You decide it's time for George to do some flying. So you press and hold AP for 1.5 seconds, then press HDG, then select 7000 feet, then press ALT, and are subsequently confused as to why the KAP-140 won't allow you to use the UP button to select a vertical climb rate.



The key is understanding that the KAP-140 goes into VS (vertical speed) mode by default when your press the AP button. The mistake was pressing ALT, which engages altitude hold mode irrespective of the altitude you just dialed in - an odd design, to say the least! Pressing ALT a second time restores VS mode and allows you to enter a vertical climb rate. The problem is that the second time you press ALT to enter vertical speed mode, the altitude you selected is not armed. That means you'll climb, but the KAP-140 will not capture the selected altitude and if you're not paying attention, you'll bust your clearance. Blast!

Having your own SOP (Standard Operating Procedure) for autopilot use, combined with actually looking at the modes being displayed, can help circumvent this problem. A better knobology sequence would be: Dial in 7000 feet, pitch up for the desired climb rate, press and hold AP for 1.5 seconds, then press HDG, then press ARM. This results in the following KAP-140 display: HDG [AP] VS 7000 ALT Armed. The KAP-140 will climb at 500 feet per minute, fly the bugged heading, and level off at 7000 feet.

Unexpected Mode Changes
In an effort to make the pilot's job easier, Garmin's G1000 will automatically switch the navigation source from GPS to a localizer on an ILS, LOC or LDA approach. Interestingly, the G1000 won't automatically switch back to GPS for the missed approach procedure - you must manually switch the navigation source back to GPS. While this may sound like a good feature, it actually creates unintended consequences in aircraft equipped with a Bendix/King KAP-140 autopilot. Here's the setup.



You're flying the Concord LDA RWY 19R approach, approaching from the South, you've requested pilot navigation, Travis Approach has approved, and you're cleared to "cross KANAN at or above 4000' cleared LDA 19 right approach." You've selected and activated the approach on the G1000 with KANAN as the IAF. Your KAP-140 autopilot is engaged in NAV and ALT modes and it is flawlessly tracking a direct course to KANAN.

Crossing KANAN, the GPS sequences to fly the procedure turn and the KAP-140 continues to do a great job. You select 2500 feet, press ALT to enter VS mode, press DN a few times to command a 400'/min descent, and remove some power to keep the airspeed under control. The GPS and the KAP-140 turn the airplane to the outbound procedure turn, then after a minute, they turn the airplane inbound to intercept the approach course.

Reaching 2500 feet, you restore some power and the G1000 then automatically switches the navigation source to the localizer. If you're not observant, you will miss this mode change. The HSI needle changes color from magenta (for GPS) to green (for the localizer) and the switch in navigation source causes the KAP-140 to silently enter ROL mode. That's right, there's no aural alarm to alert you that this mode change has happened, just ROL flashing on the KAP-140 display - which is out of your primary field of view. If you don't realize the KAP-140 is in ROL mode, the airplane will fly right through the localizer. Ooops!

One SOP you could use to prevent this is to always change the KAP-140 to HDG, manually change the navigation source to the localizer, and follow the GPS prompts to manually command the procedure turn using the heading bug. Once you've turned inbound to intercept the localizer, press NAV and the KAP-140 will capture the localizer course.

Missing the Missed Approach
The Garmin G1000, as well as the 430/530 GPS receivers, can help you fly the missed approach using GPS navigation as long as everything goes as planned. For an ILS approach, the GPS must handle two possible cases: The full ILS and a localizer-only approach. The GPS considers the MAP to be at the runway threshold, even though the MAP on an ILS is technically at decision height, on glide slope, and on the localizer course.

For these GPS receivers to suspend waypoint sequencing, you need to fly over the MAP at the runway threshold. Only then can you press the OBS key (or softkey) to re-enable waypoint sequencing, switch the navigation source back to GPS, and fly the missed approach using the GPS. If you don't fly over the MAP, waypoint sequencing won't be suspended and you'll need to do some more work to activate the missed approach. If you don't understand this GPS behavior, you could find yourself very confused at a high workload moment. Do'h!

Procedure Problems
Though rare, automation surprise may occur due to the way an instrument procedure was designed. This is exactly what happened to a pilot I was flying with recently on an approach I had flown many, many times before. The thing is, it had been quite a while since I flew this approach and the procedure had changed. Here's what happened.

The pilot requested the Sacramento Executive ILS RWY 2 practice approach with the published missed approach. Approach responded "... cross COUPS at or above 3000, cleared ILS 2 practice approach." The pilot selected the approach and activated it with COUPS as the initial approach fix. The autopilot was engaged in NAV mode and flew us to COUPS. What happened next was both dramatic and unexpected.

Reaching COUPS, the GPS commanded a 41 degree heading change to the left from a 015 track to a 334 track to navigate to the newly added Computer Navigation Fix (CNF) UBIYI: A 41 degree heading change for a leg that is only 0.2 miles long! The groundspeed was only 110 knots, but there was no time for GPS turn anticipation to smooth this out. As soon as the GPS commanded a turn to the left, it commanded a turn back to the right as the airplane blew through the approach course. It happened so fast that we both wondered what was wrong. Was this a GPS error or an autopilot error?

No sooner had we begun to doubt the automation, the plane was headed back to intercept the localizer. You have to look really closely at the chart to see that the GPS and the KAP-140 were just trying to fly the approach as it is coded. I emailed the FAA to suggest they take another look at the unintended consequences of the change that was made. Good idea!

Ounce of Prevention
The primary ways a pilot can prevent automation surprise are both simple and straightforward:

• Know your own limits with regard to currency/proficiency
• Know thy aircraft's equipment
• Monitor what the automated systems are doing
• Stay ahead of (or at least be in synch with) ATC's game plan
• Maintain situational awareness
• Develop and use SOPs (standard operating procedures)
• And be prepared to catch and correct errors.

I'd like to be able to tell you that the average pilot can fly a G1000-equipped aircraft once a month and maintain instrument proficiency. Sadly, this is usually not the case. Unless you are practicing regularly with a G1000 PC Trainer or other simulator, you'll get rusty - fast! Part of this erosion of skill is due to the vast number of features the G1000 offers, but much of the problem lies in the user interface's annoying design that requires you to recognize subtle changes in operational modes. I don't want to mince words here: The G1000 and other GA GPS receivers are not easy to use. They require regular use and practice for pilots to maintain proficiency.

PC-based simulators can be an effective and inexpensive way to maintain your instrument chops, but you need to have a plan. Sitting down and just screwing around is not going to serve you well. As they say in the music world: "If you play when you practice, you'll practice when you play."

A suggestion I've made before is to treat your autopilot and GPS like you would a low-time private pilot. It's okay to trust the systems, but monitor them to ensure they are doing what you intended. This is particularly important during transitions to climbs, descents, level-offs, turns to a heading, and intercepting and tracking a navigational course. So periodically interrupt whatever you were doing to ensure George is still flying the plane the way you intended. Did it capture the altitude you programmed? Has it intercepted the navigational course you intended? Is the autopilot still operating in the mode(s) you intended? If not, promptly drop what you are doing, intervene, fly the plane, and then try to determine why or George will trim you into a stall, flying you into the ground, or take you off course.

Remember that you are the last line of defense when automation goes bad. Never, ever forget that fact.

Barbs, Teardrops, HILO

Sorry for the delay since my last post. I've been busy ...

Procedure turns (PTs) are maneuvers that allow a pilot flying in instrument conditions to reverse direction and, if necessary, loose altitude. There are mainly two flavors of PTs depicted on Instrument Approach Procedures (IAPs) - the barb and the holding pattern (sometimes called Hold In Lieu Of a procedure turn or HILO). While conceptually simple, procedure turns can cause misunderstandings with air traffic control if the pilot is not up to speed on the regulations.

As always, don't use any of the following illustrations for actual navigation.



When flying the NDB version of the MOG NDB or GPS A approach, the procedure turn is required because the pilot must fly over the NDB station to establish his/her location prior to beginning the approach and descending. Knowing where you at the start of this approach procedure is important because there's plenty of terrain around to run into. You'd be cleared to MOG at a certain altitude, cross the station, turn outbound and track the 157˚ bearing from MOG for a minute or two, then turn to a heading of 112˚ for a minute (procedure turn outbound), then turn to 292˚, intercept the 337˚ bearing to MOG, and begin descending.

It's important to note that without GPS, RNAV, or other specialized equipment, you really don't know exactly where you are while flying the procedure turn. You only have positive course guidance when you are flying inbound or outbound from the NDB and you only know exactly where you are when you cross over the NDB or when you descend out of the clouds and obtain sufficient visual references.

The most common procedure turn is the 45˚shown below. Cross the Final Approach Fix and fly outbound for a minute or two (depending on the wind and your aircraft's performance), then turn 45˚ in the direction of the barb and fly for a minute, the do a standard rate 180˚ turn and intercept the inbound course.



Another accepted procedure turn is the 80/260. Once outbound on the approach course, turn 80˚ in the direction of the barb, then immediately turn 260˚ in the opposite direction to intercept the inbound course.



You can also fly a teardrop procedure turn, but it's a little more complicated. Cross the final approach fix and proceed outbound for 1 or 2 minutes (depending on the wind and your aircraft's performance). Then you turn either 30˚, 20˚, or 10˚. How long you fly outbound depends on the offset chosen; 30˚ for 1 minute, 20˚ for 2 minutes, or 10˚ for 3 minutes. When the alloted time is up, make a standard rate turn back to the inbound course, depending on the offset you chose: For 30° turn 210˚, for 20˚ turn 200˚, and for 10˚ turn 180˚. That's a lot to remember, but it gives you added flexibility in how long you want to make the procedure turn last.



On many (most?) procedures where the barb is depicted, the PT is neither required nor expected (more on this later) when you are being vectored by ATC. But if you need to fly the PT, you can maneuver however you want as long as you stay on the same side of the approach course where the barb is depicted. You also must stay within the distance depicted, usually 10 nautical miles from the final approach fix.

Some IAPs depict a holding pattern that can be used for course reversal and I'll refer to these as HILO (Hold In Lieu Of a procedure turn). In these cases, you have to enter and fly the hold as depicted. As you turn inbound in the holding pattern, you'll be established on the approach course. The holding pattern at WINCH (shown below) may or may not be required, depending on how you approach the fix. For RNAV approaches, the Garmin units will ask you if you want to fly the hold when you load the approach, but they don't ask for other types of approaches like VOR, ILS, or LDA approaches.



Often ATC will ask you to "report procedure turn inbound" and many pilots do not understand what this means. "Procedure turn inbound" does not just mean that you've begun your turn to intercept the approach course. It means you have completed your course reversal and you are established on the inbound approach course. Seasoned controllers will often avoid the potential confusion by just asking you to "report established inbound."

When I did my first 135 indoc training several years ago, I was impressed by how Director of Ops cut the Gordian knot when he described whether or not to execute a procedure turn or a HILO on a vectored approach:

"Don't" was the simple answer.

I later expanded that simple answer a bit:
"Don't fly a procedure turn or HILO on a vectored approach without first asking ATC."

When in doubt, ask. That's the most foolproof, all inclusive answer I can offer to the often asked question "When can I or should I do the procedure turn on an approach?" That's the gist of it and if you want to stop reading now, you can.

Still reading? Well for the long answer, let's all turn in our hymnals to 14 CFR 91.175. Buried in this section of the regulations entitled "Takeoff and Landing Under IFR" is a little kernel of wisdom on holding patterns and procedure turns, stuffed in here as if there wasn't any better place. Or were the authors of the regulations just trying to create their own sort of Easter Egg hunt? We may never know, but let's press on.

(j) Limitation on procedure turns. In the case of a radar vector to a final approach course or fix, a timed approach from a holding fix, or an approach for which the procedure specifies “No PT,” no pilot may make a procedure turn unless cleared to do so by ATC.

When using a Garmin GPS unit like the 430, 530, or G1000 to load an approach, especially a non-GPS or non-RNAV approach, it's easy to have a moment of confusion. Let's consider this clearance:

Barnburner 123 is cleared to the Santa Rosa airport, fly heading 310, radar vectors Sausalito, Sausalito 330 radial, BURDE, Santa Rosa 141 radial, COATI, direct. Climb and maintain ...

30 miles out from STS, you tell Oakland Center that you have the latest surface weather observation (ATIS) and you request the STS ILS RWY 32 approach. Center tells you to proceed direct to COATI and to expect the ILS and so you begin briefing the approach.


You load the approach, selecting COATI as the initial approach fix since that was what your clearance contained. When you're done, you see something odd on the flight plan page: Why in the hell is the procedure turn in there?

The high workload of single-pilot flying may cause you to miss the fact that procedure turn is in the flight plan, but looking at the moving map should give you pause.

14 CFR 91.175 is pretty clear that you shouldn't fly the procedure turn in this scenario since you're going to be pretty much aligned with the straight-in approach course. Approaching from the northwest, well that would be different story. So why doesn't the 530W see that you're approaching from the south and figure out that you don't need the procedure turn? Good question ...

Now you could just fly the localizer and ignore the fact that the 530W wants you to turn around after you reach COATI, but then you'll lose the distance and time to each waypoint on the approach. To delete the procedure turn, you'll need to press the FPL (flight plan) button, press the small knob to enter cursor mode, scroll with the large knob to highlight the procedure turn, press CLR, and press ENT twice. A faster and safer solution is to cursor past the procedure turn (or HILO) and press the Direct key, then ENT twice.





In the next installment, I'll discuss vectored approaches with HILO.