Three Ways to Start an Instrument Approach: Vectors, IAF and Intermediate Fix (IF)

January 28th, 2014 by Max Trescott

KPAO GPS 31

A friend lamented on Facebook that the NDB procedure at the airport where he learned to fly is no longer available. He added  “For some reason it makes me a little sad.” I’m guessing his sadness had more to do with his feelings about learning to fly at that airport, than it did about flying an NDB approach. Or perhaps he was reminiscing about the pride he felt in mastering the NDB approach.

I used to enjoy the intellectual challenge of flying an NDB approach and the even greater challenge of teaching others to master it. But no more. There are no NDB approaches left in the S.F. Bay area where I teach and I say “good riddance.”

The approaches were inaccurate and difficult to fly and former Secretary of Commerce Ron Brown was killed when U.S. Air Force pilots failed to correctly fly a rare “dual NDB” approach. I’m much prefer to see pilots expend their intellectual horsepower on mastering flying IFR approaches with modern GPS receivers, which can be more work than learning NDB approaches, and staying up to date on rule changes.

One rule change that frequently causes confusion among pilots and controllers alike relates to the third way to fly an instrument approach. All instrument pilots know you can fly an approach with vectors or use pilot navigation to start at an IAF (initial approach fix). However there’s a third way that’s been around since 2006, but word about it has been slow to get out to pilots and even to a few controllers.

Pilots can now start an instrument approach, with some restrictions, by flying directly to the IF (intermediate fix). Just to remind those who may have forgotten, the initial segment of a typical instrument approach procedure starts at an IAF and ends at the IF. So typically the IF is the next fix after the IAF as you fly toward the airport.

You might be wondering, “What’s the big deal, why would I want to skip the IAF.” For many approaches it won’t matter, especially if the IAF is along your direction of travel toward the airport. But for some approaches it can save a few clicks on the Hobbs meter. For example, at my home airport of Palo Alto, Calif., the GPS 31 approach has two IAFs, but both are in the boonies and most pilots start the approach at DOCAL, the IF.

You’ll find the details about starting an approach at an IF in section 5-4-7(i) of the Aeronautical Information Manual (AIM), where it first appeared in 2006 (yes eight years ago!). However, you won’t read about it in the FAA’s Instrument Flying Handbook or even in the FAA Instrument Procedures Handbook, both of which are excellent publications.

The rule applies to all approach types, not just RNAV (GPS) approaches. Here’s the current text from the AIM:

ATC may clear aircraft that have filed an Advanced RNAV equipment suffix to the intermediate fix when clearing aircraft for an instrument approach procedure. ATC will take the following actions when clearing Advanced RNAV aircraft to the intermediate fix:

1. Provide radar monitoring to the intermediate fix.

2. Advise the pilot to expect clearance direct to the intermediate fix at least 5 miles from the fix.

NOTE - This is to allow the pilot to program the RNAV equipment to allow the aircraft to fly to the intermediate fix when cleared by ATC.

3. Assign an altitude to maintain until the intermediate fix.

4. Ensure the aircraft is on a course that will intercept the intermediate segment at an angle not greater than 90 degrees and is at an altitude that will permit normal descent from the intermediate fix to the final approach fix.

Here’s what it means to a typical GA pilot.

1) You need to be GPS equipped (which is the only practical way for most GA aircraft to be RNAV equipped). This let’s you find your way independently to the IF.

2) The controller might advise you that you’ll be starting the approach at the IF, but more typically, you’ll have already requested that of the controller.

3) You’ll be assigned an altitude to maintain until reaching the IF. Most likely you won’t be on a published segment of the approach until the IF, so you need to be assigned a safe altitude.

4) The controller cannot clear you directly to the IF until you’re in a position from which you can make a turn of less than 90 degrees to join the approach at the IF.

It’s the last part, making a turn of less than 90 degrees, where pilot and controller sometimes get confused. The idea is that the turn at the IF needs to be an easy one, much like turning left or right at the intersection of two streets. It can’t be a hairpin turn or resemble something like a U-Turn.

Think of it this way. If you were to draw a line on your chart at the IF that’s perpendicular to the intermediate segment, on one side of the line, the side farthest from the airport, you are allowed to fly directly to the IF, since the turn inbound is less than 90 degrees. If you’re on the other side of the line, the side closer to the airport, you can’t be cleared to the IF until after you’ve been vectored across the perpendicular line.

All of this presents some new challenges for pilots and controllers, especially if they’re unclear on the rule. We’ll talk more about those challenges….next month.

Max Trescott

Max Trescott specializes in teaching in glass cockpit aircraft. He is best known for his Max Trescott's G1000 Glass Cockpit Handbook and Max Trescott's GPS and WAAS Instrument Flying Handbook. He formerly worked for Hewlett-Packard and now is a full-time flight instructor. He is the 2008 National CFI of the Year. Visit Max’s website.

Tags: , , , , , , , , , ,

The opinions expressed by the bloggers do not reflect AOPA’s position on any topic.

  • John

    Why isn’t DOCAL marked with (IF)? I have seen (IF) on many IAPs including KCDR ILS2 when using TST as the IAF.

    • David

      That’s the trouble with BLOGs. Nobody is responsible for the reply. And the reply has no authority, since it is essentially from an unknown person. I too wonder why DOCAL is unmarked as IF.

      • Max Trescott

        David, I’ve replied to John.
        Max

    • Max Trescott

      John, I compared many GPS approaches and all which had “RNAV (GPS)” in the title had the IF marked. The title of the Palo Alto approach is “GPS 31″ which means it’s a fairly old GPS approach that hasn’t been updated to the new “RNAV (GPS)” format. My guess is that when the FAA’s Western Flight Procedures office updates the PAO approach to the new format, they’ll mark the IF on the chart.

    • John

      I noticed in this year’s AIM 2014 that is no longer in there (they stop at sub-paragraph h). It was in 2012′s, not sure about 2013. So does this mean they will no longer approve this approach? I am currently working toward my instrument rating and any info would help.

      Thanks

      John

  • Danny Wallace

    Excellent article,
    I’ve practiced this approach method many times in the simulator but not used it in the aircraft and found it gets a little busy fast at times. But like anything else, practice makes perfect, you save a lot of time not having to go to a point farther away from your airport of intended landing just to line up on final. The new educational experience for me from reading this article is, I never knew there were any restrictions or rules against performing the approach this way in the past. Thank you for the insight.

    • Max Trescott

      Danny, I’m glad you found the article helpful! I wrote it because I’ve seen a lot of confusion among pilots and controllers about this topic.

  • Clifford H. Rice

    Being a pilot with more that 28,000 hrs. of flight experience, I can assure everyone that the old ADF approach is easy to teach, a piece of cake to fly, and does not require any more mental gymnastics to execute than an ILS approach does.

    All VHF nav aids, VOR, Localizer, GS, transmit two signals that the equipment in the plane uses to determine where it is in relation to the course being tracked whether vertical or horizontal. Both, the ground transmitters and the receiving equipment in the plane must be calibrated for accuracy. As everyone knows, the VOR equipment installed in the plane only has to be accurate with in a few degrees thus the requirement for keeping an accuracy log in a plane.

    Ever wonder why there is no requirement to keep an NDB accuracy log? The answer is simple, since the ground station transmits only one signal, and the equipment in the plane only has to use one signal, there is no error! Granted, there were other problems with low frequency transmitters and receiving equipment which were usually easily identified.

    Being a pilot with more that 28,000 hrs. of flight experience, I can assure everyone that the old ADF approach is easy to teach, a piece of cake to fly, and does not require any more mental gymnastics to execute than and ILS approach does.

    All VHF nav aids, VOR, Localize, GS, transmit two signals that the equipment in the plane uses to determine where it is in relation to the course being tracked whether vertical or horizontal. Both, the ground transmitters and the receiving equipment in the plane must be calibrated for accuracy. As everyone knows, the VOR equipment installed in the plane only has to be accurate with in a few degrees thus the requirement for keeping an accuracy log in a plane.

    Ever wonder why there is no requirement to keep an NDB accuracy log? The answer is simple, since the ground station transmits only one signal, and the equipment in the plane only has to use one signal, there is no error! Granted, there were other problems with low frequency transmitters and receiving equipment which were usually easily identified.

    Bottom line, the ADF is only as accurate as the compass in the plane is. With good equipment, someone who knows what they are doing when flying an NDB approach can split the center line of the runway as accurately and easy as can be done with the localizer!

    • Rich Sugden

      I had the same problem w. ADF approaches … always had to go over them at least twice!! :o)

      • Max Trescott

        Rich, very clever. Of course a little redundancy never hurts :-)

    • James Carlson

      This isn’t entirely accurate. A VOR transmits two signals — a master reference signal (AM modulated) and a phase-varying directional signal on an FM subcarrier. The phase relationship between these two signals gives the radial. For an ILS, the localizer and glide slope use four signals and compute a difference in depth of modulation between them. They’re actually implemented differently, which is why the OBS does nothing when tuned to a localizer.

      The key difference here is that the orientation of the receiver (the aircraft) doesn’t matter with those techniques, but it matters greatly with an NDB, because an NDB is just a simple AM transmitter, and the receiver has to use directional antennas to figure signal direction. The accuracy depends on a number of factors, including the orientation of the aircraft (including bank!), the terrain features (buildings and bodies of water), time of day (day/night), signal strength, and so on.

      The reason there’s no “NDB check” as there is when using a VOR is that such a check would just be impractical. There’s no CDI to center, and accuracy on a good day isn’t that great anyway.

      As for splitting the centerline, NDBs are (unlike localizers) rarely right on the centerline at the field. So good luck with that.

  • Marc Rodstein

    “Being a pilot with more that 28,000 hrs. of flight experience, I can assure everyone that the old ADF approach is easy to teach, a piece of cake to fly, and does not require any more mental gymnastics to execute than an ILS approach does.”

    You’ve gotta be kidding. There isn’t one pilot in a hundred that would agree with that. If it is so easy, how come nearly everybody hates the thought of doing one? And don’t even start talking about accuracy! Especially if the approach requires outbound tracking, accuracy stinks. And that is without lightning static, which makes the signal nearly unusable.

    Speaking for the 99%, I agree with Max. Good riddance to ADF approaches!

    • shane dougal

      I guess I am one of that 100. Having flown dozens of NDB approaches (in a commercial airliner mind you) they are easy to do, with the right equipment, an ADF comes to mind. But you are right, the signal can be unreliable. Having said that, I have lost RAIM (WHILE ON THE APPROACH!) many times, more then I every had a problem with a NDB, so I don’t think there is a valid argument there. Just another example of the “new” glass-autopilot aviator from the “old” steam gage-hand flown folks. (Both skills are equally important these days.)

      • Max Trescott

        Shane, have you lost RAIM on a GPS approach recently? GPS has gotten much better in recent years. The last time I checked, basic GPS availability int he U.S. was running 99.99%, suggesting you’d only lose RAIM about one in 10,000 times when flying to LNAV minimums. That’s very reliable. LPV availability is not nearly as good, especially in Alaska. Still it is well over 99% availability in the lower 48 states and the outages are typically no more than 15 seconds. So perhaps one in 100 times, you wouldn’t be able to fly to LPV minimums, but in most of those cases LNAV minimums would still be authorized.

        • shane

          Not only have I lost it several times in the past year, but on the same approach. It has more to do with the approach then the GPS itself. GPS-W into KSUN (hailey ID), it happens usually right over the FAF, I don’t know why, but I’m guessing that it is because of the terrain (flying into a canyon) Most of the time it “comes back” quickly, but many a time I have gone missed, (that’s why my company has developed alternate missed if you lose RAIM, we must have the HLE NDB functional for this, go figure).

    • Max Trescott

      Hi Mark…nice to see you here. I totally agree with you. To that I’ll add whether ADFs are good or bad is fast becoming irrelevant (at least in the lower 48 states)…because they are disappearing rapidly!

  • Charles Gibbs

    Programming this on a Garmin 430/530 is a little tricky. Since there are three options for transitioning, I first tried (on the sim) using Vectors to final; but, it assumed I wanted a Rwy to PUDBY extended line. So, I next loaded one of the IAF transitions, activated it and then highlighted DOCAL and punched in direct to DOCAL. Is this my only option? Is this the best?

    • Dave Zittin

      “So, I next loaded one of the IAF transitions, activated it and then highlighted DOCAL and punched in direct to DOCAL.”

      Yes it is your one and only option, providing the controller has cleared you for a direct-to DOCAL.

      If the controller vectors you onto a segment of the approach, you highlight the end fix of the segment and use “activate leg”. Do not use direct-to end of leg!

      Now you know why vectors-to-final is not a good idea in all cases, the runway line does not follow the approach beyond PUDBY (FAF). I personally do not care for this ambiguity and would rather have a vector to the approach “outside of PUDBY”, or even better for reduced workload, a direct-to DOCAL when able (see Max’s comment on the less than 90 degree issue).

    • Max Trescott

      Charles, yes that’s the best way (and the only way!) to accomplish this with a Garmin 430/530.

  • http://justpickone.org/davidtg/ david t-g

    Sure, I’ll be happy to “expand [my] intellectual horsepower” … as soon as you’re happy to cough up the money to glass-ify my lovely steam-gauge 172, thank you. Not every airport has a localizer/glideslope or VOR approach, and for many small airports it’s either the acclaimed GPS or the lowly NDB. Yes, I’m sure I’ll have some sort of approved position source within the next six years or so, so just maybe I might be able to afford to fly a GPS approach, but until then the only way I can get to my home airport under IFR is via the NDB approach.

    • Max Trescott

      David, you’re ahead of me–my plane is VFR-only!
      No question, an NDB can still do the job. But the FAA continues to decommission them at a rapid rate, primarily to reduce the money they need to budget each year for maintenance. I hope your NDB stays around at least until you add a GPS to the plane.

  • Greg Faris

    I don’t agree with the 28000h pilot (maybe that’s 14000h, but printed twice makes 28? Only joking)!
    NDB’s ARE more mental gymnastics to deal with than other instrument approaches. Personally, I find these to be fun gymnastics to deal with, and there is definitely a sense of satisfaction in practicing them. They have a few things going for them, like no twisting to reset the instrument after a course reversal, and if you have an RMI they are much easier to fly. They hone your airmanship skills as well, as your tracking is thrown off by even a moment’s lapse in precise heading control. So I do not agree with those who say “good riddance” but when the weather is low I definitely feel more reassured with any other type of approach.
    To those who say “good riddance” – be prepared to say “hello again” the day you fly outside the US. In many European countries, major airports are equipped with ILS CATIII and RNP, but as soon as you get out of the major hubs (where small planes are not allowed anyway) you will be working with the NDB penetration, usually with holds in lieu of procedure turns.

  • Ross

    NDB approaches require no more mental gymnastics than other approaches, provided one is trained and is competent with ADF tracking, both to and from a station. Once learned, I agree that ADF approaches are very simple: no twisting of OBS or CDI knobs, it gives an accurate portrayal of one’s position at all times, and though it may not always lead to runway centerline, it will allow one to find the runway. It’s also very easy to hold or arc.

    Like the high-time pilot, I was trained in instrument flying in the Navy in 1969, and have always considered having an ADF as an excellent backup. It can even be used to track to a local AM radio station. Today’s pilots have a bad attitude towards it, which they could change if they really learned to use it. The skills also transfer readily to use of an RMI or HSI, using the pointers.

    So since competence in ADF navigation may still be required on FAA exams and practical tests, I would advise pilots to drop their opinions, probably based on other student pilots who haven’t accepted and learned to use it. Learn it, and you will have expanded your piloting knowledge and situational awareness.

    Since ADF has no ‘off’ flag, remember to monitor the identifier while navigating with it. That’s no harder than identifying a VOR or ILS before using it, which I hope is observed religiously (but I doubt it).

  • Colin Malaker

    Great Article … thanks!!

    BTW .. that Ron Brown thing. If you really delve into the thing you will find that they found a bullet hole in his head during the initial post crash exam and there must have been a massive cover up. Another Clinton cover up. Bad stuff.

  • Chris Thrasher

    Great article.
    When I did my Instrument rating, none of the planes I flew in the process had a operational ADF receiver on board. A couple were deliberately “inop” to preclude the Examiners from requiring its usage.
    I think the general mind set and aversion which most pilots I encounter have to the ADF system stems from the horrid test questions which appear on FAA Written Exams. Folks get burned out on ADF long before they ever have an opportunity to actually correctly learn and utilize them.

    Once I completed my IFR rating, I stumbled into a situation in which I was given the “keys” to a Redbird FMX sim and free reign to use it to my heart’s delight. I brought in my instructor and we “flew” all the unusual and irregular approaches we could find. NDB, back course etc etc. It was valuable experience but it was also valuable experience which had the FMX usage not been Gratis, I probably never would have actually pursued.

    As to using the IF over the IAF. Meh….if you are familiar with the approach and terrain, sure go for it. If you’re not, why would you want to cut yourself short on prep time during an approach? Just my thoughts.

    • Max Trescott

      Chris,
      I’m sure lots of people placarded the ADF inop before a checkride. Of course to be legal, there would also have to make a logbook entry in the aircraft logs–which examiners are smart enough to look for! You raise a good point about being familiar with terrain…if you start at the IF, you’re relying on ATC to vector you above the Minimum Vectoring Altitude (MVA) for that area until you get to the IF. Of course the same is true if you start at an IAF…though many IAF’s are on airways or feeder routes, so you’re a little more likely to have published route minimums if you start at an IAF.

  • Ben Lopez

    Flying the ADF is interesting. What makes it more interesting is what kind of ADF system your using. The old fixed card ADF is different from the RMI ADF, that most airlines used. The fixed card ADF did require a lot of mental gymnastics. Most pilots skipped this process in their early training because their instructors didn’t know how to instruct the fixed card ADF system. The discussions between instructors and students got rather interesting when considering that VOR radials were outbound from the station and ADF bearings are inbound to the station. That caused a fair amount of verbal confusion for students and instructors.
    Example, if your using a fixed card ADF and your airplane is heading is 090 degrees and the ADF needle was pointing to 050 degrees, then you were crossing the 140 bearing to the station (090+50 =140 bearing). That put you northwest of the station, since a 140 bearing is inbound to the station. So turning the airplane to the right 50 degrees you would be flying to the station. When learning ADF flying and identifying your position, a good instructor would never make it so simple. He would then say, now intercept the 90 degree bearing on a 90 degree intercept angle and fly to the station. We’re in the NW quadrant of the ADF station and the 90 degree bearing is going inbound to the station, so it would be the same as the 270 degree radial. You would turn your airplane to a heading 180 degrees and that would put you on a 90 degree intercept to the 090 degree bearing and upon intercepting you would lead your ADF needle by 10 degrees to complete the turn inbound on the 090 degree bearing. This got even more fun when working in other quadrants of the ADF station. Because if you were on an aircraft heading of 300 and the ADF needle pointing 240 degrees, you first had to add (300 + 240= 540-360 =180). So your crossing the 180 bearing due north of the station. This exercise in identifying your position in relation to the station and then flying a specific bearing inbound to the station or outbound was the only way to truly understand ADF. This gave you the ability to know what quadrant of the station you were in for situational awareness. Once you figured that out, it was easier to fly an intercept bearing to or from the station. So, when I hear the conversation about the ease of using ADF, I frankly doubt that most have really learned these principles in a way that it would never be forgotten. Only and instructor that taught this regularly might remember it in his old age. For the rest of us we more than likely ram dumped it within days of doing it. Ben

    • Max Trescott

      Ben, I think you raise some interesting points. Yes, flying an ADF approach in an airline with an RMI is much simpler than flying it with the fixed card ADF typical found in older single-engine aircraft. I’ve only flown one single-engine trainer with an RMI and it had been purchased from a flight school in northern California that had a contract to teach airline pilots for JAL. And yes, after the IFR checkride, I suspect many GA pilots do forget the subtleties of flying ADF approaches (a RAM dump, as you said). Of course, I think they also forget the finer points of using the GPS after the an IFR checkride. We still have a long way to go to make avionics easier to use.

  • Warren Webb Jr

    Many great comments, everyone. We used to have an NDB approach at Hartford-Brainard (KHFD) which used the same course as the LDA to runway 02 (the NDB was its FAF). Before the NDB was decommissioned and before GPS approaches added more options, you could count on doing an ILS, a VOR, and an NDB approach for your checkride. That may still be the case in some locales. The NDB approach could be flown about as accurately as the LDA if one were proficient, which was easy to see during many practice approaches flown in VMC over the same landmarks. On one trip I took to Piqua, OH years ago, the only available approach was an NDB and it was IMC – so being proficient with the NDB approach, we made it in easily in a Baron 55 and avoided a diversion. Another commenter made a great point about traveling to Canada where someone today may encounter the same circumstances.

    Max’s lesson on approaches starting at the Intermediate Fix is a good one. This concept started way more than eight years ago. I’ve had ATC vector me on a downwind parallel to the approach course, and then turn me in to set up the 30 degree intercept angle just outside the IF. Now that is service. This didn’t occur on a GPS approach but in a C172 in the Jurassic age (about 20 years ago) for the VOR RWY 2 approach to Westfield-Barnes Rgnl (KBAF) still available today. The IF is NUTTN INT. In this case, the approach starts in Bradley’s Class C airspace, so you can imagine that ATC can’t have the pilot starting at another fix and creating conflicts with a number of airliners, or doing a procedure turn causing the same problem.

    Bottom line, the more options a pilot has, the better – but don’t attempt something if not proficient. I found the NDB approaches plenty accurate and was glad to have them as an option but they were a higher mental workload than VOR’s and ILS’s.

    • Max Trescott

      Warren, no question, ADF receivers are still handy to have in Canada, Alaska and other parts of the world. Regarding your example flying the VOR RWY 2 at KBAF, what you describe about being vectored on a “30 degree intercept angle just outside the IF” sounds like you were getting classic vectors. Maybe I’m missing something, but it doesn’t sound at all like starting an approach with up to a 90 degree turn at the IF.

      • Warren Webb Jr

        Max, I meant to comment on the general concept of starting approaches at the IF (“You’ll find the details about starting an approach at an IF in section 5-4-7(i) of the Aeronautical Information Manual (AIM), where it first appeared in 2006 (yes eight years ago!).”, not so much on the technicalities of the turn. It sounded to me that you were saying that approaches never started at IF’s before 2006.

  • Ben Rolfe

    It is sad to see so many people never learned to fly an NDB approach. As a CFII I love the ADF for one very good reason: it is an outstanding way to reinforce fundamentals. When I find an instrument pilot who is having trouble flying accurately, 9 times out of 10 the problem is in fundamentals, and often it is as simple as not holding a heading. The ADF tells you nothing if you can’t hold a heading accurately and consistently for long enough to get an accurate bearing. When a pilot is having trouble nailing the localizer or glideslope, I used to take them up and do NDB tracking and approaches. The most common slop I see flying an ILS is too much movement and never flying a stable, constant heading or descent rate long enough to figure out how to adjust – chasing the needles prevents a really accurate approach. With the ADF, if you can’t hold a heading it all goes so badly wrong, it makes a good teacher. With a VOR or ILS, needle chasing seems to work OK for a while, that pilots don’t see the root cause of those final heroic gyrations near the runway.

    As to the mental gymnastics, it really is simple if you learn it right and understand what the ADF is (and isn’t ) telling you. And god yes my antique radios are SOO much easier to use (and there is really no excuse for the “new” stuff being so user unfriendly). I’ve found that teaching with the ADF made everything else come more quickly. Sadly, it is a tool no longer available.

    Now, anyone want to talk about my most VERY favorite approach gimmick – DME Arcs?

    B

    • Max Trescott

      Ben,
      I totally agree about “the ‘new’ stuff being so user unfriendly.” There is a lot of room for improvement!
      Max

  • Ben Lopez

    Ben Rolfe, I agree with you about the art of flying ADF. I also used ADF as a tool to learn basic instrument flying. As you can see from my example, having to think reciprocally to figure your quadrant from the station was great for adding levels of orientation and to help the students learn to multi-task. You can only do so much basic instrument flying and not bore your student to tears. Using stair step learning methods made the boring endeavor of basic instrument instructions more interesting for the student and the instructor. Ben

    • Max Trescott

      Ben, I agree, approaches with many step-downs really make students (and pilots) work hard. The good news is there are plenty of non-NDB approaches left with lots of step-downs. Sure, tell us about your approach gimmick for flying DME Arcs.

  • Eric

    Can anyone answer John’s question about why DOCAL isn’t marked “(IF)”? Is it just an oversight, or does it have some meaning?

    • Warren Webb Jr

      Eric, I did some poking around in the approach chart legend and in terps but haven’t seen any explanation so far. I have a contact at Bradley International who over many years has been able to answer questions of this type. So I sent him an email and I’ll let you know what happens.

      • Warren Webb Jr

        Eric, Here’s the answer I received to your question from a support specialist for airspace and procedures at the Bradley TRACON, Windsor Locks, CT. Max is correct. Approaches with the title of ‘GPS’ like this one use old design criteria that is no longer used. When the procedure is reviewed again, it will be brought up to current criteria (RNAV etc). He believes the old criteria left it to the procedure designer to label the fix as an ‘IF’ or not. And in reality most times this was an oversight on the designer’s part, and it slipped in without it.

        On the other hand, with the intermediate fix not being labeled ‘IF’, the controller’s handbook specifically states in 7110.65 Par. 4-8-1d2, that one of the conditions to issue an approach clearance to an aircraft proceeding direct to the IF, is that the fix be labeled ‘IF’. Without it, ATC is not permitted to issue that approach clearance. It does happen, but it is not supposed to.

        Out of curiosity I looked at probably thirty airports around the country via SkyVector looking for another ‘GPS’ only approach, and would you believe I could not find even one. Max, you must have the last or near the last ‘GPS’ approach.

  • Stanley Salter

    Expecting a technical and mundane read, I became very
    interested in the polarized responses that were elicited from this
    article. In particular, I noted that
    the experienced professional pilots, Mr. Rice and Ross, seemed to be in
    disagreement with a comment that the ADF approach is “inaccurate and difficult
    to fly”. My curiosity led me to the Ron
    Brown Air Force Accident Investigation Board Report referenced in the article.
    I was surprised to find:

    The investigative board determined that the approach was not
    approved for Department of Defense aircraft and should not have been used by
    the aircraft crew. This particular approach required two operational ADF
    receivers and the accident aircraft only had one.

    The resulting CFIT accident was not due to any shortcoming
    involving the ADF approach. The type of approach was irrelevant. No approach
    should ever be attempted if the required equipment is not available. In fact, the cause of the accident goes
    beyond pilot error and borders on pilot stupidity.

    It appears to me that, in this instance, the reputation of
    the ADF has been unjustly besmirched. I
    greatly appreciate the learning opportunities these forums provide.

  • Pingback: watch salem season game of thrones season watch duck dynasty season

  • Pingback: student loan consolidation

  • Pingback: chloe sims removing taking off gel nails at home

  • Pingback: boutique dresses wholesale uk

  • Pingback: charlotte garage door services

  • Pingback: proper lighting

  • Pingback: t-mobile store in rolling meadows