Fibbing to the FAA

GPS Satellites in Orbit

I’ll admit that I fib to controllers. Not about my altitude, or airspeed or course, but about approach procedures. I secretly track GPS/RNAV approaches without telling.

The good news is that the FAA has proudly announced that it has published 3,052 LPV (localizer performance with vertical guidance) procedures as of mid January. An LPV is the approach that mimics and replaces an ILS in terms of precision and reliability.

The FAA has also published thousands more, 6000 in all, I believe, GPS/RNAV approaches. Those procedures all have lateral guidance with excellent accuracy, and many also have glideslope style vertical guidance. Those are called LNAV with V procedures.

I congratulate the FAA for moving more quickly than I ever thought possible to take advantage of GPS accuracy and availability. And to accommodate airplane owners who have installed GPS navigators in droves.

But I fib to controllers because all of this wonderful progress in creating GPS/RNAV approaches hasn’t made it to the radar control room. Most controllers I deal with continue to believe that an RNAV approach is a different animal than say an ILS, or VOR procedure and must be flown differently.

Invariably if I ask to fly the GPS/RNAV approach instead of the conventional procedure being advertised as active I am cleared to some distant fix far out on the approach. If  I were to fly the ILS the controller would simply vector me toward the localizer center line of the approach at some distance outside the final fix. There would be no need to go to an initial or intermediate approach fix. But ask to fly the LPV to the same runway and the controller sends me to an initial fix instead of vectoring me to the “localizer.”

There is absolutely no reason to treat the GPS approach any differently than a conventional approach. The centerline of the procedure is the same for the LPV and the ILS it overlays. A GPS approach on top of a VOR procedure is the same path over the ground. In our cockpits we can see the centerline right there on the moving map. Many flat glass displays have a dotted flight path prediction line so you can see where you will intercept the centerline of the approach based on your present heading.

My solution to this complication is to accept the clearance to fly the ILS while really having the LPV dialed in. The controllers see me intercept the LPV centerline exactly as I would the localizer of the ILS. And they see me start down at LPV glidepath interception just as I would when capturing the glideslope of the ILS. Everybody is happy.

And I don’t think my fibs are breaking any rules. I dial the second navigator to the ILS frequency. I glance at the “green needle” of the raw data ILS and confirm that it matches the LPV exactly. So I get the rock steady signal of the LPV while monitoring the less stable ILS signal. Am I really flying the ILS as I was cleared to? Yes. I am. I am flying exactly down the center line of the ILS even though the LPV is what I look at most for guidance.

Of course, the minimums can be different for a GPS approach versus a conventional procedure so you need to compare and be sure you know which decision height or visibility requirement to observe. For example, at my home airport at Muskegon, Michigan, the LPV minimums are the same 200 and one-half as the ILS to Runway 24. But on Runway 32 the LPV decision height is 300 feet compared to 200 feet for the ILS, but the visibility minimum is the same one-half mile for both procedures.

The FAA says it is totally committed to a world of WAAS aided GPS navigation. The entire Nextgen air traffic system is based on WAAS and GPS. And the procedures are established. All I want to do is fly those wonderful procedures without the hassle of flying extra distances to get out to some initial approach fix.

The FAA has even helped me in my innocent fibs by using the same names for final approach fixes on both ILS and LPV approaches in most cases. When GPS procedures were first overlaid on existing approaches the GPS procedure typically had different names for fixes, even though the outer marker or final approach fix was the same point on the ground. I used to compare the ILS and GPS approach charts to see if the fixes were in the same spot and to report the name of the ILS, not the GPS fix. But that’s not a problem anymore.

What I really think is happening is that many controllers do not understand that GPS, especially the LPV approach, is a total replacement for ILS. No procedural changes are needed for either pilots or controllers.

And I think there is also the issue of radar presentation. Controllers may not have, or may not be sure, of the exact path of the GPS approach course on their radar screens. For that reason they clear us to an initial fix so that we fly between fixes instead of intercepting a centerline that isn’t depicted on their scope.

I plan to keep telling the little white lies and fly the LPV or GPS approach. And I’ll dial up the conventional signal, too, until ATC catches up.

This entry was posted in Mac Clellan's Left Seat Blog. Bookmark the permalink.

19 Responses to Fibbing to the FAA

  1. Bruce Ziegler says:

    Similar thing happens at my home base (5G7) where we can get vectors to the VOR final approach course, but not the the RNAV LNAV+V approach. They told me it was because the RNAV approach course wasn’t shown on their screen yet but would be in a future update to their equipment.

  2. Tom says:

    Around here, our old-as-the-hills, “get-me-within-a-mile-or-so-of-the-field” NDB approach still exists. Funny thing is, the NDB approach is authorized day and night. The LNAV approach to the same runway, with nearly the name minimums, is NOT authorized at night. Many of the local RNAV approaches have this same restriction. What the deal with that?

    • Mac says:

      The FAA has a set of approach standards called TERPS that define clearance from obstacles, accuracy of approach guidance, runway lighting and so on to set minimum altitude and visibility standards. TERPS, like all FAA rules, evolve, but procedures that have been certified are not always brought up to different standards. So an NDB approach certified years or decades ago may not be possible if it were being created today, but it’s there and so it gets to stay there. In general the FAA does not remove certification from an airplane or activity because it sets a new standard for future airplanes and procedures. For example, there are airplanes that continue in production with flying qualities–stall behavior or stability–that would not pass in a newly certified airplane. But they met the rule when certified so they are allowed to continue. And that makes sense. If every airplane in production had to be modified to meet every new certification requirement it would be impossible to produce airplanes.
      So, an NDB approach that’s been around for years may have lower minimums than a new GPS/RNAV procedure with its superior guidance and along track position information. The solution is dial in the ADF frequency and then fly the GPS guidance.
      Mac Mc

  3. Margaret says:

    Having just started Instrument ground school, understanding the integration of the older nav technologies – which seem foreign to me compared to GPS – is one of the more interesting and tricky aspects. Thanks for sharing your “approach” to using the new to validate and support the old standard.

  4. Thomas Boyle says:

    It struck me, during my instrument training and when flying with instrument-rated friends, that IFR operations have a remarkably high level of “insider tricks”. It also struck me that the conceptual architecture of it all is very non-obvious, which probably accounts for why there are so many tricks, loopholes, etc. No doubt it was all carefully thought-through at each step, but now it just seems like a mess.

    Probably only because I don’t fully understand it.

  5. Dave says:

    If I understand your contention, you want to be vectored to intercept the RNAV final approach course inside the intermediate fix, but outside the final approach fix, just like an ILS. Unfortunately, FAAO 7110.65, the “Controller’s Bible”, prohibits the controller from vectoring you, or clearing you, to intercept an RNAV approach inside the intermediate fix, and then only if you have “advanced RNAV equipment.” That’s why you’re not getting vectored closer, they can’t! Read 4-8-1 and 5-9-1.

  6. BillyBob says:

    A big problem we have in central AL is non-radar airspace and pilots not understanding radar is required for GPS/RNAV operations. REF AIM 1-1-19 d.1. IFR GPS are considered area navigation (RNAV). According to AIM 5-3-4 3. Area Navigation requires radar monitoring.
    REF FAA 7110.65 4-4-2 Route Structure para g. Provide radar monitoring when transitioning…
    If the final approach course is not depicted we cannot vector something not displayed. However I have vectored outside a fix thereby creating an intercept of less than 90 degrees, making the course reversal unnecessary.

  7. Joe says:

    Mac –
    We need more commentary on GPS – its a technology I think we all want to maximize. Change is coming, and I am glad that the FAA is embracing it. However, i think Dave’s comments above are important to note – the first question in my mind while reading your article was, “Did Mac talk to anyone at ATC?” Makes me wonder if Dave is a controller……. Bottom line – if you can get more input from the guys and gals in the tower and at TRACON/Center, I bet we’ll get a clearer picture of what is going on, and consequently, what needs to change to avoid having to play these approach games. I appreciate your intention, but I personally like it best when i’m on the same page with approach control.

  8. Dave says:

    Yes, Joe, I was a controller, now retired. Spent 31 years in center, FSS and terminals, the last 24 in a tower with TRACON. Handled all the automation and radar mapping for my last 18 years. I am a pilot and have some instrument time, not rated, but passed the FAA IFR test in college.

  9. J.D. says:

    I am an active duty Naval Aviator, test pilot and general aviation pilot who just joined EAA on a 6-month trial membership. I am sad that this is the first article I’ve read and cannot believe your cavalier attitude toward flight safety and established procedures. I’m appalled that you, according to your profile, are a CFII and are advocating to pilots to lie about instrument approach procedures to the FAA. Not only are RNAV approaches different than ILS procedures, there are completely different certification requirements involved. While you may think that you’re flying the same ground track as an ILS approach on your RNAV LPV approach, you are using a completely different references to ground locations and obstacles. I would hope this fact is obvious, but according to your article you don’t understand the basic differences between ILS and GPS. EACH ONE OF THESE APPROACHES MUST ME CERTIFIED SEPARATELY, and the FAA spends a great deal of money doing so.

    The F/A-18 has a TACAN, but not a VOR installed. I cannot fly a VOR/DME approach to a VORTAC station using the TACAN signal, even though the radial and distance information is present. While it may seem that the VOR part of the VORTAC and the TACAN part of the VORTAC are covering the same piece of sky, the TACAN bearing isn’t certified for the approach. If I were caught flying an improper approach in IMC, the best result is that I lose my wings and never fly again.

    Believe it or not, the FAA is trying to save lives. If the EAA’s stance on flight safety is in keeping with the theme of this article, I may ask that my name be removed from the roster and I will certainly not be renewing my membership after the trial period is complete. At best, you lose my membership. At worst, the author or a reader does something that results in their death or the death of a loved one. Aviation is a dangerous environment, procedures are written in blood and instrument procedures are nothing to fib about. EVER.

    • Thomas Boyle says:

      I see that you have strong feelings about this.

      I also understand that there are procedures for certification and that, for example, GPS and ILS are different technologies that are not certificated as substitutes for each other.

      But – Mac’s approach seems both sensible and legal (he is, in fact, using the ILS equipment for the approach and, legally, is merely using the GPS as an aid to situational awareness).

      Do you know that there is a practical concern with using this kind of philosophy – or even (if Mac were doing so) with using a GPS in lieu of an ILS – or are you warning us not to assume that there isn’t?

      I ask, because experience has taught two lessons. One is that FAA certification standards are often excessive – and not just a little excessive, but excessive to the point of parody. The other is that sometimes they’re not.

    • Bob says:

      Six month trial membership! Evidently you’re not certain if you really want to waste your time impressing the unwashed masses with your tales of daring in the mighty Fa/18!

      Here’s a tip for you. Blogs are one person’s opinions and or experiences and don’t generally imply or claim to be talking on behalf of anyone else such as the EAA. You don’t have to agree with Mac, or how he fly’s approaches, but making general statements about the EAA like you are is wrong.

      If you can step down off of your high horse long enough, you may just find out how much the EAA has to offer you.

  10. KB says:

    As several other controllers’ comments illustrate, the real issue is the pace of rule making not keeping up with technology. There are a lot of ways we’d love to make use of what we know works, and works well, we just can’t because we’re not allowed by current procedures. Controllers also don’t yet have the toolsets to use some advanced navigation capabilities effectively at busy airports. NextGen is putting a lot of pressure on the FAA to change this and they are making some noise about doing it, but it could be hampered some more by budgetary issues. Either way, it’s still going to be a while. Stay tuned and keep your fingers crossed.

  11. Eugene Maximov says:

    Mac, I’m with you!
    All the reflections on the article carry good sense but of J.D. an effusive reaction. In my opinion, this on 6 months trial terms EAA member? is appears to be unnecessarily sharp and immodest. One would expect of the seasoned test pilot to be more open-minded to innovations coming in. Besides, to be an EAA member is a credit to every pilot… and vice versa.

  12. Pingback: C’est vendredi, on fait le tour! (6) « comiquaze

  13. Hugh Tapper says:

    As long as Mac Has the VOR/ILS dialed in and does monitor it, the GPS gives him an excellent and easy to follow guide. There is nothing illegal or unsafe in that,as long as you dont bust the minimums for which ever has the lowest minimum altitude.

  14. Pingback: Little White Lies | High Altitude Flying Club

  15. Jim says:

    Also don’t forget to fly the published missed procedure for the ILS. Often dramatically different than the GPS LPV missed approach.

Leave a Reply

Your email address will not be published. Required fields are marked *


You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>