GPS Approaches & WAAS, Glide-Slope Intercepts & Portable Electronic Devices

by Michael J. Mick Kaufman

In my previous column, I concluded a series on the procedure turn – when to do one and how to eliminate doing one illegally according to FAA protocol.

A short time ago, I received a phone call from one of our readers, Bert Gosch, the flying button box player from La Crosse, Wis. We talked about his music (which I enjoy) and GPS approaches which gave me one of my topics on the next series for my column – GPS approaches and WAAS. Another reader, Mick McMahon of Madison, Wis., planted the seed for another topic on glide-slope intercepts and the news of allowing portable electronic devices to be used during all phases of flight, prompting a few additional comments for this issue’s column.

It is hard to move forward on the GPS approach topic without giving some history on how we arrived at where we are today in GPS navigation. The approaches we are now doing are mostly the result of one radio equipment series – the Garmin 430/530 – and for that reason I will be explaining several approaches and how they are accomplished on these two boxes in this column and in several of the following issues of Midwest Flyer Magazine.

We have moved forward from the Garmin 430/530 with newer technology, but these boxes will be the gold standard in GPS boxes for many years to come, as the King KX-170s were several decades ago. I still see the King KX 170 in many airplanes I fly; they just keep on working.

Even though the overall vote goes to the Garmin 430/530s, my favorite is the Apollo CNX 80, later known as the Garmin 480 after Garmin’s acquisition of UPS technologies. There is a cult out there of Garmin 480 fans, and I am one of them.

Early in our transition away from VOR and ADF navigation, there was Loran C that filled a gap before GPS gained its popularity, and there were a few Loran approaches commissioned. The next phase of GPS approaches were overlay approaches, which used existing approaches (VOR & NDB) and configured them for use with the GPS. I am not sure if there are any overlay approaches still in use at this time. So much for the short history course on navigation!

With so many approaches for a majority of U.S. airports, you will need to make a decision on which approach you would like to do. The decision should be based on weather, wind direction, runway in use, published approach minimums and direction from which you are approaching the airport. A review of the approach charts and current weather are very helpful at this point. If you are planning a landing at a busy airport, the ATIS will be advertising the approach in use, but that does not preclude the pilot from requesting a different approach. At non-tower airports, air traffic control will often ask the pilot which approach he would like to make and the initial approach fix or transition desired. I mentioned above checking several items to help you make a decision on the approach to choose.

It is interesting that the minimums for two LPV (Localizer Performance with Vertical Guidance) approaches to the same airport or runway can be radically different. An example is the LPV 09 for the Lone Rock, Wis. airport (KLNR), which is 381 feet lower than the airport’s LPV 27. If you were faced with low minimums and light wind, my choice would be Runway 09.

Once the approach has been selected, we need to set them up on our Garmin 430/530s. With KLNR selected as a Direct To waypoint or the destination (last waypoint in a flight plan sequence), we press the “procedures” button. The GPS responds by offering us a list of approaches to select. If we do not see the one we wanted from the list, we scroll down the list and the approach should appear below.

After selecting the approach by pressing “enter,” the next question the Garmin asks us is how do we want to get established on the approach? One of the options listed is “radar vectors.” My preference is never to select this option unless it is 100% assured that we will actually get radar vectors. The reason I suggest this is because it is an easier process to select a full approach and amend it to vectors to final than it is to reconfigure an entire approach sequence should ATC make a last minute change, or if they did not intend to give us vectors to final.

If we study the approach charts prior to choosing a plan of action, we will notice that there may be several initial approach fixes and transitions to the selected airport.

If you read my previous series on eliminating a procedure turn, you may remember that all approaches begin at an initial approach fix  (IAF) with some exceptions.

So let’s assume we choose an initial approach fix (IAF) and there is a transition taking us from an airway intersection to it. We return to the Garmin GPS, select it with the right scroll knob, and hit the enter key. We now can see what we have done and if it looks good, we have two choices… We can enter it into the current flight plan (load) or activate it at this moment. If we choose to activate it, the GPS now plots our course from our present position to the first waypoint in the approach. If we had chosen and activated vectors to final approach, course guidance is discontinued and the box will show the extended final approach course in a magenta color. If we are not ready to go there at that moment, we should have just loaded the approach, not activated it. There are a lot of other details I will cover in the next issue of Midwest Flyer Magazine, but we have now loaded a basic approach with a transition and an initial approach fix. The next issue will cover editing it and flying it.

Reader Mick McMahon sent me some excerpts from another publication and I thought them interesting enough to dedicate some space in my column to comment. I am addressing this topic with my thoughts, and many of you may not agree with me. You may email me with your opinions, which I value. The argument here is, when should we descend – and to what altitude – on a precision approach (approach with glide-slope or vertical guidance).

This depends on two criteria: clearance given by ATC and/or the published altitude on the approach chart.

Creating a scenario around the approach chart in FIG 1, let’s assume our final clearance was “Cessna N2852F, maintain 3,000 until established on a published segment of the approach. You are cleared for the RNAV/GPS 9 approach to the Lone Rock airport. Report cancellation or down time on this frequency or through flight service.”

Putting the aircraft at the position I depicted in FIG 1 at 3,500 feet MSL when this clearance was received, when may I descend below 3,500 feet, and when would I as a pilot descend?

Looking at the approach chart, the lowest altitude authorized for the segment I am on is 3,000 feet. I would descend to 3,000 feet after receiving this clearance.

After passing “FINKO” – the intermediate fix (IF) – the lowest authorized altitude is now 2,600 feet. The 2,600 feet indicates this with a line under it in the profile view on the chart. The underline below this altitude on the profile view is the minimum altitude allowed for that segment of the approach. If this were a mandatory altitude, there would be a line above and below that published altitude in the profile view on the chart. Here is where the controversy comes in… After the aircraft crossed FINKO, the glide-slope should became active and show that the glide-slope is above the aircraft (a good thing). The chart indicates that the aircraft may descend to 2,600 feet for this segment, but I would not do this. With the glide-slope above me, I would wait for it to come down to my altitude and center while at 3,000 feet. I would then follow it down from that point. In my opinion on a stabilized approach, either with the autopilot on or off, it eliminates making an unnecessary pitch and power change. While on the autopilot, it gives the aircraft more time to get established on the descent profile as well. This technique will not work on an approach without a glide-slope with multiple step down fixes, as you always want to take advantage of being able to reach the minimum descent altitude as soon as allowed by the published procedure. I also use this technique on ILS approaches, as it makes a much smoother transition to the descent profile. I teach this procedure to my instrument students and modestly accepting some bragging rights, they make good instrument pilots and fly great precision approaches.

One extremely important point I would like to add at this time may be a lifesaver in low instrument conditions on an ILS approach.

On the ILS 22 approach to Eau Claire, Wis. (KEAU) (FIG 2), it shows glide-slope intercept at 2,900 feet with the aircraft crossing the final approach fix (FAF) at 2,866 feet. The final approach fix (FAF) is depicted as 7.3 DME on the frequency of 109.5 Mhz. This is the spot where you can make a final altimeter check; they should match within a close tolerance. If they do not match, you may be in trouble and should make a missed approach.

Two items can cause an error as I have found out; you have the wrong altimeter setting or there is an instrument error in the altimeter or glide-slope indicator.

The last issue I wish to comment on deals with use of “portable electronic devices” in aircraft below 10,000 feet. The airlines used to have a strict rule that all passengers turn off portable electronic devices during the climb, final descent and approach (below 10,000 feet). The news media has been talking about this and on a recent flight to Richmond, Va., the flight attendant during her safety briefing stated: “You do not need to turn off your portable electronic devices, and we are the first airline to implement gate-to-gate use of portable electronic devices.” WOW!

For what it is worth from a guy who has worked with electronics for a good share of his life, this decision by the FAA and the airlines is a bad one. We don’t know what interference could be generated by these devices that could cause an ILS or autopilot deviation during an approach. The combination of selected ILS frequency and two or three portable electronic devices emitting so-called acceptable radiation, may overpower or capture the ILS receiver. From my experience as the former operator of a two-way radio shop and an amateur radio operator, it is not worth the risk to allow these devices to be used during the critical phases of flight – more supporting comments in the next issue of Midwest Flyer Magazine.

Till then, blue skies and tailwinds!

EDITOR’S NOTE: Michael J. “Mick” Kaufman is a Certified Instrument Flight Instructor (CFII) and the program manager of flight operations with “Bonanza/Baron Pilot Training,” operating out of Lone Rock (LNR) and Eagle River (EGV), Wisconsin. Kaufman was named “FAA’s Safety Team Representative of the Year for Wisconsin” in 2008. Email questions to captmick@me.com or call 817-988-0174.

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