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Thread: Little Help With the PROC feature of GPS

  1. #1
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    Default Little Help With the PROC feature of GPS

    I am having some trouble utilizing the PROC function of the GPS in the B737-800. I want to fly a standard approach to the destination airport/runway, but I don't seem to be able to push the right buttons.

    What happens is, I press PROC, and then SELECT APPROACH. I next then ILS28 because I plan to make an ILS landing on RWY 28. I then must choose either VECTORS or HRV under "Trans." Here, I don't know what to do, so I have been selecting VECTORS. I don't know what HRV stands for or what it does.

    Next, I either select LOAD or ACTIVATE, depending on how far out I am. As I get closer to the airport, I will ACTIVATE if I have previously put the approach into LOAD. I have no idea how far out one should be before ACTIVATING the approach.

    OK - with the approach activated, and the airport coming up, I can zoom out on my Flight Plan view, and see a dotted white line (which was not there before) winding around the airport. It will have a hold circle in it and will appear to be the approach that I have selected. The problem is, the aircraft will never coincide with the dotted white line. It will generally fly over the airport and then begin a turn that will ultimately get it lined up with the intended runway, but I don't think that's the way it's supposed to work.

    What am I doing wrong? I keep the plane in GPS mode during all of the above.

  2. #2
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    Which airport for the ILS28 approach?

    OK - with the approach activated, and the airport coming up, I can zoom out on my Flight Plan view, and see a dotted white line (which was not there before) winding around the airport. It will have a hold circle in it and will appear to be the approach that I have selected. The problem is, the aircraft will never coincide with the dotted white line. It will generally fly over the airport and then begin a turn that will ultimately get it lined up with the intended runway, but I don't think that's the way it's supposed to work.
    An ILS approach (or any approach) might have different pieces, depending on the airport, the surrounding airspace, the terrain and maybe other factors. You need to provide the airport so we can look at the approach plate, and you need to mention what your heading and (relative) position is when you start this (big effect on the plane's path). You also might describe the turn a bit better than just "begin a turn" -- does the aircraft head away from the airport on the same side of the airport as the approach, go straight for a bit, then turn? Is it more than one turn? Is it anything like the holding pattern, or perhaps it's a 45º turn (right or left), brief straight, then a 180º, then turning on to final?

    Please supply some additional info to help us help you.

    Larry N.

    As Skylab would say:
    Remember: Aviation is NOT an exact Science!

  3. #3
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    Quote Originally Posted by lnuss View Post
    Which airport for the ILS28 approach?



    An ILS approach (or any approach) might have different pieces, depending on the airport, the surrounding airspace, the terrain and maybe other factors. You need to provide the airport so we can look at the approach plate, and you need to mention what your heading and (relative) position is when you start this (big effect on the plane's path). You also might describe the turn a bit better than just "begin a turn" -- does the aircraft head away from the airport on the same side of the airport as the approach, go straight for a bit, then turn? Is it more than one turn? Is it anything like the holding pattern, or perhaps it's a 45º turn (right or left), brief straight, then a 180º, then turning on to final?

    Please supply some additional info to help us help you.
    Will do. SB - going to dinner right now, but will get back to you ASAP. And thank you!

  4. #4
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    The white dotted line is the path to the holding point. If you decide to do a missed approach, the gps will fly the white dotted line to the holding point and the airplane will circle until you decide to do something else. On the approach you have 2 choices. 1 is to land the airplane manually using the gps to keep you lined up to the runway. On my lazy flights I will use this method. Actually I use the gps to line me up a lot. 2. long before you get to the ILS, having the gps line you up, dial the ILS frequency in nav 1 and at some point in your approach, switch to NAV and activate the ILS for an ILS approach. Basically the PROC is used to line you up to the ILS.

  5. #5
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    the gps will fly the white dotted line to the holding point and the airplane will circle until you decide to do something else.
    The OP said:

    The problem is, the aircraft will never coincide with the dotted white line. It will generally fly over the airport and then begin a turn that will ultimately get it lined up with the intended runway,
    which is why we need more information to help him.

    Larry N.

    As Skylab would say:
    Remember: Aviation is NOT an exact Science!

  6. #6
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    Quote Originally Posted by pdmike View Post
    I am having some trouble utilizing the PROC function of the GPS in the B737-800. I want to fly a standard approach to the destination airport/runway, but I don't seem to be able to push the right buttons.
    This is exactly the same situation I found myself facing when trying to use the Garmin 530. I opted for what I consider the far more intuitive GPS gauge by Gavin Munro available here in the library. Just do a search for "munro" (no quotes) and you will find a host of panels he has developed as well as the GPS gauge. He basically has taken all the functions of the Garmin and reprogrammed them into an easy to read and execute functions. You won't have to guess what button or arrow to click and in what order to bring up the function you are looking for, and then try and remember in what order you selected them in order to return to where you started. Commands are in easy to read labels and Icons.
    HP Omen Obelisk, i7 9700K 3.6 Base to 4.9 Turbo Boost, Nvidia GeForce RTX 2060 Super 8GB, 32GB HyperX 2666 DDR4 RAM. 1TB 7200 SATA HD, 1TB Western Digital M.2 NvME SSD, 750W PS. Let's fly!

  7. #7
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    Quote Originally Posted by lnuss View Post
    Which airport for the ILS28 approach?

    (1) An ILS approach (or any approach) might have different pieces, depending on the airport, the surrounding airspace, the terrain and maybe other factors.

    (2) You need to provide the airport so we can look at the approach plate, and you need to mention what your heading and (relative) position is when you start this (big effect on the plane's path).

    (3) You also might describe the turn a bit better than just "begin a turn" -- does the aircraft head away from the airport on the same side of the airport as the approach, go straight for a bit, then turn? Is it more than one turn? Is it anything like the holding pattern, or perhaps it's a 45º turn (right or left), brief straight, then a 180º, then turning on to final?

    Please supply some additional info to help us help you.
    (1) I understand that there may be a number of different approaches to any given airport and that each of these approaches may not have the same number of pieces (or segments).

    (2) I'll fly the thing again. I am approaching the Reno-Tahoe airport at 18,000 feet, 75 miles out from the airport in a stock, Boeing 737-800. I am flying a heading of 330 with GPS in control of the plane. I am not using ATC. As I begin the descent, I load an approach plan by doing the following: PROC/SELECT APPROACH/ILS16R/VECTORS/ACTIVATE. i notice that now, when I go to the alternate page of my flight plan, the various "pieces" of the approach have appeared: Approach ILS16R; TAKLE;RW16R; 6500; FMG; NICER; There is more, but it is off at the bottom the screen and I don't know how to scroll down to see it. (Question: What is all that other stuff doing in there below RW16R? I never use it. The only "pieces" I use are TAKEL and RWY16R.)

    So, having activated my approach.I continue my descent. As I do so, I notice that the GPS line of flight (in red) no longer appears on my main, flight plan page. Descent continues. I continue on a heading of 331. (I have leveled off at 12500 ft. because there is a mountain in the way of my descent path and I have to hold the descent at 12500 in order to get over the mountain. After leveling off, I am on a heading of 338.)

    As soon as we clear the mountain, the descent continues to 6,600 ft., which is 2000 ft. AGL. Note: The NAV/GPS switch is on GPS and the NAV HOLD switch is ON. Descent continues. I am now 6.8 miles out. The RWy16R ILS frequency is on. The airport is ahead, on my left at an estimated angle of 20 degrees. My heading is 331. My approach plan says I am heading for TAKLE and that is 17 miles away. I am now at 9,000 ft., flying right by the airport on a heading of 331. (I know, I know .... I started my descent a little too late but it is what it is.)

    Once I reach TAKEL, the plane begins a left turn. The next point of the arrival plan is RWY16R. I began the turn at a heading of 336. At the end of the left turn, the plane levels off on a heading of 128, 8 miles out from RWY16R. I switch to NAV and hit APP. The plane immediately begins to turn left - I assume to pick up the localizer. The plane then descends and crashes into the ground - I guess because when I activated NAV and hit APP, it deactivated ALT HOLD and I didn't notice that.

    If I had not crashed, the plane would have picked up the locaizer and I would have done an ILS landing on RWy16R.

    (3) See above for a description of the turn.

    So - that's it. Is this the way an Approach is supposed to work, because it seems to me there is an awful lot of unnecessary flying around the airport before landing.

    And what about the crash? Are we supposed to immediately re-activate the ALT HOLD, once we switch to NAV and hit APP?
    Last edited by pdmike; 03-09-2021 at 05:25 PM.

  8. #8
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    OK, I am looking at an approach plate for the KRNO 16R ILS, dated SEP 1999. The reason I'm using this one is because it's what I have on hand that still defines the points you are using (circa 2005) in FSX. The current plates are quite different, and there are two approaches for 16R.

    First thing to note is that TAKLE is the IAF (Initial Approach Fix) for the 16R ILS at KRNO. TAKLE is actually an intersection defined by the junction of the 316º radial from the Mustang (FMG) VOR and the I-RNO localizer. Of course on the GPS it is just a waypoint. The approach plate shows that you should be at 9000 MSL (not 6600) on the north side of TAKLE before turning inbound, then come inbound on the localizer descending to 8500, then cross TAKLE inbound at 8500 or intercept the glide slope at 8500 about 12 DME (nautical miles) from the runway. Before reaching this point you should have been established on the localizer for a while to let the aircraft settle down (hopefully you are down to a reasonable approach speed, not cruise speed before starting your descent, let alone trying the start the approach).

    I've included the approach plate I'm looking at below, so you can see what I'm talking about, but wife just indicated supper soon, so I'm going to save this post for a while, then come back to add to it later.

    Meantime, I want to mention something that may seem obvious to you, but needs to be brought to the front of your mind in discussing this. One reason for all the seemingly (to you) excess flying around in the area is that the design of the approach must first consider that the pilot can't see anything except clouds outside, and it must consider safety, both in altitude and in azimuth, that is, plenty of clearance from terrain AND obstacles (radio towers, buildings, etc.) throughout the approach, right down to touchdown. The FAA (and regulators in other countries) have established certain minimum altitudes and distances to clear the various things, and those are adhered to throughout the approach. Another reason is that, especially in faster aircraft, even at their slower speeds for approach, things can happen fast, and a pilot's mistakes must be allowed for (up to a point). And finally, the limitations of the nav equipment (including radio wave reflections from odd objects, odd atmospheric phenomena, etc.), human reaction time and perceptions, and more are considered. AND the aircraft MUST be on a stabilized approach path prior to reaching the IAF.

    One other note before I stop for the moment: Try hitting the APP mode before crossing TAKLE outbound, so that the GPS software has a chance to put the aircraft where it needs to be. Also, this approach is actually set up to use the NAV radios in ILS mode, and the approach chart I show is designed to navigate by VORs, not by GPS (that is true of the design of the approach in the GPS too).

    Back later for more.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	ILS 16R KRNO 1999 sm.jpg 
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    Larry N.

    As Skylab would say:
    Remember: Aviation is NOT an exact Science!

  9. #9
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    OK, I'm back. I'm flying the approach in a Baron (don't much care for the sim's airliners), and I was well southeast of the airport inbound on a northwesterly heading, with the GPS directing the AP Direct To KRNO. At about 12 NM from KRNO at 9,000 ft I activated the approach. The aircraft immediately made a right turn to head to a point somewhat past TAKLE -- the red line shows I will go well north of TAKLE, then a very sharp left turn to get on the localizer. A turn like that should instead become a procedure turn (the 45º left turn outbound at the top of the chart, with a barbed tip, and headings of 299º outbound and right turn to 119º to then intercept the localizer inbound.

    The aircraft turned left quite a bit short of where the red line took that obscenely sharp left turn, and made a circle back to get aligned with the localizer (I stayed at 9000 ft through all this) then flew right over the field. Nowhere on the GPS display did it show the procedure turn arrow, BTW, which hurts trying a coupled approach.

    So I went back well southeast again to give this another try. This time I flew from well southeast direct to KRNO then, almost over the airport activated the approach. This time it went straight out to TAKLE then, at TAKLE, started that left turn again. This is still at 9,000 ft, which needs to be maintained until established inbound on the localizer but outside TAKLE, where you descend to 8500 to pick up the glide slope (can't do that on GPS -- must switch to NAV and use NAV radios to perform the approach.

    What is all that other stuff doing in there below RW16R? I never use it. The only "pieces" I use are TAKEL and RWY16R.)
    It's used for other things. Ignore NICER and its associated holding pattern, that's for missed approach.

    As soon as we clear the mountain, the descent continues to 6,600 ft., which is 2000 ft. AGL.
    Why so low? Anyway, that's not 2000 AGL, except maybe at one or two spots. It IS 2200 feet above the field, but is way too low for there -- don't descend below 9000 until established on the localizer inbound, then only to 8500 ft, letting the glideslope guide you down once it's engaged (in NAV, of course).

    I am now at 9,000 ft., flying right by the airport on a heading of 331. (I know, I know .... I started my descent a little too late but it is what it is.)
    Too late? Again, 9000 until inbound on final outside (north of) TAKLE.

    Once I reach TAKEL, the plane begins a left turn. The next point of the arrival plan is RWY16R. I began the turn at a heading of 336. At the end of the left turn, the plane levels off on a heading of 128, 8 miles out from RWY16R. I switch to NAV and hit APP. The plane immediately begins to turn left - I assume to pick up the localizer. The plane then descends and crashes into the ground - I guess because when I activated NAV and hit APP, it deactivated ALT HOLD and I didn't notice that.
    Don't press APR or APP (whichever it is on your craft) until you are on final, as stated above, at 9000 ft well north of TAKLE, inbound and nearly on the localizer. You should still be a few miles from TAKLE when you do this. Then switch to NAV mode and hit APR.

    Note: In the vertical profile view on the plate (the part with the odd lines under the main plan view) it says "Remain within 10 NM". This is referring to the point (labeled 9000) where you turn around to go inbound, you should not be further than 10 NM N of TAKLE -- this is for terrain clearance.

    Hope this helps. Gotta go for this evening, but give it a try, perhaps with a bit more understanding now of what's involved, and being aware the the approach depiction (and guidance) for the GPS is usually less than perfect in FSX. There are approach plates for every published instrument approach, and the current version of each is online somewhere, though there have been changes in the 15+ years since the data that FSX uses was compiled.

    Larry N.

    As Skylab would say:
    Remember: Aviation is NOT an exact Science!

  10. #10
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    Final note here, with a better solution for you. Last night I was tired, and trying to duplicate your flight using VECTORS for the approach. For doing that you need to have ATC involved on an IFR flight plan and let them vector you to the approach. If instead of VECTORS you had selected TAKLE (maybe 10 NM out, or so, inbound to KRNO) it would have taken you through the outbound portion of the approach north from TAKLE and even through the procedure turn and would have established you on the localizer inbound, at which point you'd descend to 8500 and switch to NAV (from GPS) and then press APR on the AP. Assuming you're near 8500 when intercepting the glide slope the AP will start your descent when the GS needles center. You'll want approach flaps before TAKLE inbound and gear down no later than reaching TAKLE (then full flaps, of course).

    All the above need to be done at approach speed. 175 kts and more through the procedure turn will have the AP overshooting a lot, trying to correct then overshooting some more, so at least get it down to 150 kts -- I don't know what your aircraft needs for approach speed.

    Hopefully you've learned a few things. I've certainly reminded myself how FS works on the GPS -- it's been years since I tried much IFR stuff in the sim, mostly flying with a friend VFR and sightseeing.

    Larry N.

    As Skylab would say:
    Remember: Aviation is NOT an exact Science!

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