Readback: February 2012


Best Foot Forward
I really appreciate the article by Chet Ludlow “Setting Limits in IMC” published in the December issue of IFR. With initial recurrency instrument students, I have taught this way for many years and found it most effective. However, even when I apply the maximums of Chet there is still a missing ingredient.
That ingredient is inadvertent adverse yaw. Almost universally the pilots who wander back and forth, even minutely on an ILS final, are doing it without rudder. Consequently, at the initial input of bank, however small, the heading indicator goes the wrong direction. Thus the pilot holds the bank too long before returning to level wings and goes through the course.

The leveling of the wings ends up also with adverse yaw, which leaves the aircraft pointing away from the course. The reaction is to immediately turn back to the course—and thus repeat the errant process of a continuum of pilot-induced oscillations across the course. This is often aggravated by knee-jerk responses to attempt to stop the wandering from course. The term “chasing a needle” often applies well.

An illustrative exercise is to have the pilot, flying with visual references, put their feet on the floor and rock the yoke back and forth. Unless the aircraft is designed with connected controls, the nose will swing back and forth, often increasing the divergence as the inputs are continued. I then direct attention to the heading indicator to show what they are seeing when on instruments.

None have ever previously noted the slight heading change in the wrong direction when they initiate a bank without rudder. Many often express that they assumed that adverse yaw only had an effect when making major bank changes, and none have ever initially considered that adverse yaw also applies when returning from a bank to level wings.

Helping a pilot use coordinated rudder pressures, combined with Chet’s “think fast, think small” concept, solves the problem. I think every pilot I’ve worked with on this has commented, “I didn’t think I was capable of flying that precisely!”

Ian A. Worley
Cornwall, Vt.

DME to Where?
I was just reading “Belt and Suspenders” about the odd-duck approach at Akureyri, Iceland, (Decemeber 2011 IFR). Please note that the localizer and DME are not co-located as it says in the article. The DME is located where the Jepp plate shows the DME or TACAN symbol (I call it a saw-wheel), on the airport, approximately where a glideslope transmitter would be located, 0.1 miles past the threshold.

The localizer antenna is indeed offset, but if you look at the scale of the chart, you’ll notice that it is located almost two miles east of the ASR final approach course. If the DME was co-located with the localizer antenna, it would therefore not count down any lower than about 2 DME.

Incidentally, ILS-DME facilities in Europe typically co-locate the DME transponder with the glideslope transmitter, and not the localizer as the FAA does. That way the DME will read distance to touchdown, rather than distance to the overrun accident.

I noticed that the first time I looked at European approach plates. I’ve had my Apache over there twice, back in ’77 and ’85. I don’t think AeroNav charts show the actual location of a DME transponder the way Jeppesen does. I don’t like them and don’t look at them much.

Herb Pello
Benton, Kan.

The Rule of Unreason
I am aware of the restriction on using GPS in lieu of NDB for a final approach. What I’d like to know is the rationale for this.

At my home airport of La Grande, Oreg., we have a GPS approach with IAFs to the north and an NDB approach with an on-airport NDB. Most of my flights arrive from either the west or south, requiring me to spend 20+ extra minutes in IFR conditions to intercept the approach, as my plane is not equipped with an ADF.

I have asked the FAA regional office in Seattle to consider adding an approach from the west, which they claimed they would consider. This was after they told me they were not approving any more GPS overlays on NDB approaches. That was over a year ago.

Someone in the office told me, “If it were me, I’d fly the NDB approach with my GPS as long as the full approach appears on my GPS.” It does.
I know this isn’t an official approval to fly the NDB approach, but what should one reasonably do in this case? A friend with a twin Cessna with dual GNS 1000s just installed an ADF for another $8000 just so he can’t be busted using his GPS on the approach. He claims he will never rely on it, but the FAA requires it.

I am aware of a waiver for Part 135 pilots. Why can’t the rest of us get this as well?

Chip Ettinger
La Grande, Oreg.

We agree it’s a silly restriction based on regulatory obtuseness rather than legitimate safety risks. But we don’t know of any way to get the same waiver under Part 91 ops. While we can’t tell you to just fly the approach with your GPS, we won’t be the ones to tell you not to, either.

Sharing the Pain with Friends
I’ve read IFR for nearly 20 years. During that time the relevance and substance have so improved that, for me, IFR is now the aviation equivalent of The Economist, my magazine benchmark. However, I’ve rarely taken IFR quizzes. They’re hard and time-consuming enough to be daunting.

Months ago a non-pilot friend grabbed IFR from me over lunch and read the first question and each of four possible answers of a scenario-based quiz. I thought out loud. She asked questions and stoked my thinking. On my iPhone, I downloaded a FAR/AIM app. I researched the question and nailed it. Still, I missed three of 10 questions.

The next month, she said, “Why don’t we invite Dale,” a CFI. Now, Steve, a Cessna T310R pilot like me, has joined in. We pass one issue among the four of us. My friend still moderates and often says, “Hurry up, guys!”

Adding this social element and time clock to the quiz changed everything. The conversation, competition, fear of failure, and research occupies us for an hour or more on where-are-you-now quizzes, which are now a valuable, academic part of my monthly recurrency program. When I see a panel picture, I open my eyes wider. I smile in anticipation of Saturday lunch. IFR is now twice as valuable to me as it had been.

Frank Robinson
Santa Barbara, Calif.
Shore with us your pain, pleasure or perspective at [email protected].


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