Sunday, January 20, 2008

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.

Friday, January 04, 2008

VTF or WTF?

Many pilots are confused about who's responsible for terrain and obstruction clearance on a vectored approach, so here's the skinny: As long as ATC is vectoring you, they are responsible for guaranteeing obstruction clearance. Once you are established on and cleared for the approach, you are responsible for your own obstruction clearance by flying the altitudes on the approach chart.

Your approach clearance will contain the following item which you can remember with the acronym P-TAC:

1) Your Position (distance) relative to a fix or waypoint on the approach
2) Heading to Turn to or maintain
2) Altitude to maintain until established
3) Clearance for the approach.

Once you are established, comply with all crossing restrictions listed on the approach chart and you shouldn't run into anything. If there are intermediate approach fixes, you must be prepared to identify those fixes so you can maintain the appropriate altitude.

If there are several intermediate approach course fixes (IF) before the final approach fix (FAF), you're probably executing an instrument approach procedure to an airport surrounded by mountainous terrain or close to another airport that also has instrument approaches.

For non-RNAV approaches, a controller can vector you to most any point on the intermediate approach course, then give you the approach clearance. The controller's handbook says they are supposed to vector you no closer than 3 NM from the FAF with an intercept angle not to exceed 30˚ and that's usually what they do - but not always.

For RNAV approaches, controllers are restricted from vectoring you to a point inside an intermediate fix (IF). They should get you in a position where they can clear you direct to an IF with an intercept angle of 90˚ or less. And since you are RNAV (or GPS) equipped, you then resume your own navigation to the approach course and intercept it on your own.

Continuing on the previous discussion about Garmin's implementation of Vectors-to-Final for instrument approaches, I stumbled onto a way to get the Garmin 430/530, 430W/530W, and G1000 to display all intermediate approach fixes when being vectored to the final approach fix.
For the G1000, consider the Oakland ILS or LOC DME 27R:


I've seen many pilots hear a controller say "Fly heading 180, vectors for the ILS 27R," load the approach, see the "Vectors to Final" approach option, and then, almost unconsciously, select that option. For this approach, this is what you get when you select Vectors to Final. When the controller says "Barnburner 123, three miles from GROVE, cross GROVE at or above three thousand four hundred, cleared ILS 27R" you're now left trying to figure out where GROVE and UPACI are located.



Wouldn't you rather see this?



Here's how: Load the approach with the initial approach fix instead of vectors to final. Press the FPL button, press the small FMS knob to enter cursor mode, scroll with the large FMS knob to the final approach (FITKI in this case), press the MENU button, Activate Leg will be highlighted by default, press ENT twice, and you're good to go. This same sequence will also work with the Garmin 430W and 530W. The older Garmin 430 and 530 require a different sequence sequence, covered below.



If you're wondering how this setup works with the Garmin autopilot, the answer is "very nicely." Just set the heading bug to your assigned heading, activate the autopilot in HDG mode, and press the NAV button. The autopilot will stay on the assigned heading until the course comes alive, then it will turn and intercept.



As you approach the localizer course, the nav source will automatically switch from GPS to LOC.





To get the intermediate fixes to display the Garmin 530 or 430, the sequence is a bit different. For this example, let's consider the Salt Lake City ILS RWY 16R, which has three intermediate fixes outside the FAF.



Load the approach with OGD or FANDS as the transition: It doesn't really matter which one you choose.



Activate the approach and you'll be dumped into the flight plan view. Press the small knob to enter cursor mode, scroll with the big knob and highlight BNKER (the FAF), then press MENU.



The Activate Leg option is highlighted by default, so press ENT twice.



This view gives you pretty much what you need, but if you want to see the magenta line extended out farther, there are a couple more steps.



First, make sure your OBS or HSI is set to the localizer front course.



Next, press the OBS button and you'll see the magenta line extended outward. Small problem, the intermediate fixes have disappeared.



Press the OBS button again and like magician David Copperfield, you've reversed the disappearing act and the IFs are shown again.



Wouldn't it be nice if this was done automatically for you? WTF?

Wednesday, January 02, 2008

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 ...