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Thread: NAV Questions

  1. Default NAV Questions

    Hi all,

    I've flown the Cessna 172 that comes with MSFS since Meig's Field was the default flight. I never really needed much more to play around.

    Last year, I printed out some airport charts and started learning to fly IFR. I can navigate most of Georgia, USA without ever needing to look out the windows.

    At some point, I "upgraded" to a Diamond with a Glass Cockpit. I've figured out how (mostly) to set up radios and use the CDI.


    So, here are the questions that are bugging me:

    1. KCTJ has an ILS. The Localizer is 111.7. There is no other radio beacon at the airport. I use VORTAC Lagrange and Rome to navigate in and out.

    How do I know how far I am from that Airport? VORTACs give DME info, but Localizers don't. I know some places have an OMI indicator. But it seems like distance from overrun would be critical info.




    2. Can I autopilot from NAV2? I want to fly a course until I intercept a radial. Then fly that radial until I intercept the glideslope. As it stands, I fly the bug (HDG with NAV armed) with the VORTAC on NAV1 active and ILS on NAV1 standby. Once I intercept the VORTAC, the autopilot does its thing. As I approach the airport, I switch back to the bug (HDG with APR armed) and flip from VORTAC to ILS.

    Seems like there is an extra step in that workflow. Is there a better way?



    3. Does the OBS matter on a localizer?



    4. Zoom and Pan suck. No real question here. Just that FS pan and zoom gets worse with every generation. 'Member when we could put a bunch of dials and gauges on screen with a tiny little 3D window? Panning around a virtual cockpit to flip switches may be more realistic, but it sucks for practical training.



    5. Can I hide the yoke? It obscures the lighting controls.

  2. #2
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    Default

    Do you have the approach plate for the airport (which you can get here)? The lower part of that plate shows that it is 3.6 nautical miles from the IAF (Initial Approach Fix and, in this case, also the FAF, or Final Approach Fix) called GPQ to the runway. Note that the ADF is required equipment for the approach, since it defines both the IAF and FAF.

    1. On the lower left of the plate is a FAF to MAP table, which provides timings at specific (ground) speeds, ranging from 60 to 180 knots (interpolate between values) to travel that 3.6 NM. The only other indication of distance is if you're tuned to the LAGRANGE VOR, which it shows is 31.2 NM from the FAF, though not being in alignment with your approach path it will only give a rough distance approximation for you IF you can receive it.

    But there's no need for further distance information, since you must either follow the glide slope until the time after FAF has expired or until you see the runway, if on the ILS. On localizer, you want to be at 2400 MSL crossing the FAF, then descending to 1480 MSL and no lower until the runway is in sight, or until the time runs out.

    2. If the aircraft you are flying has a way to use the AP with NAV 2, then you can certainly do that, but on the NAV1 radio you can set your initial course in the active and the LOC/ILS freq in the standby (as you indicate you are doing), then just switch STBY to ACT for LOC intercept. There's no other nav facility for you to use in the NAV radios on this approach, so NAV 2 can be set wherever you like, but won't really be much help. In any case, the AP doesn't do auto switching from NAV 1 to 2.

    3. No. When you tune a localizer freq, the operating mode of the NAV radio changes so that the L/R needle (CDI) is four times as sensitive as it was in VOR mode, and the OBS is disengaged, since you'll only be navigating with that freq when intercepting and flying the designed course, and more than 2.5º (if memory serves) off course there'll be no needle change until you're within that narrow range.

    4. That's why I have TrackIR, so that I can move my head around in the virtual cockpit, even move fore and aft and up and down, with touching any keys or other controls. That's also why I have a HOTAS-style stick so that I don't have to hunt in the cockpit for most controls I use -- just use the button/knob on the stick or throttle for most things. Even when I freeze the TrackIR so that I can then use the pan and zoom controls, the button for that is on my stick. This allows me to keep my head outside most of the time (or monitoring the gauges if IMC).

    5. Some aircraft allow that, some don't. I don't normally use the default aircraft, so don't know what they do.

    Larry N.

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

  3. #3

    Default

    Although you may be flying via NAV, not GPS, you could use the GPS to give you distance information.

    The cunning pilot uses ALL the information and informatics at his/her disposal.

  4. #4
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    Hmmm -- I didn't know the sim GPS worked at all with the switch thrown to NAV.

    Larry N.

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

  5. #5

    Default

    Quote Originally Posted by lnuss View Post
    Hmmm -- I didn't know the sim GPS worked at all with the switch thrown to NAV.
    Distance is read from the face of the instrument. All it has to have is a focus - usually an identifier for the `destination`. It does NOT need to be driving the navigation.

    Plenty of YouTube videos to illustrate.

  6. Default

    I usually fly the default 747 vc. In that an ils gives distance info. (on the hsi).
    So I think ils gives distance, ils is always a combi of localiser and dme I think.
    How else to know when to start the descent? Can't if no distance is known.

    If you don't see the dme info in your 'hsi', then fixing may be more of a matter of finding a usefull gauge.
    Or of using one that is in the aircraft already. On the default pros plane radio gauge (bendix?) is a distance info option. You can switch that to nav2 or nav1 distance. Try that.
    (not at pc a.t.m. Or I would try myself first.)

  7. #7
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    Quote Originally Posted by il88pp View Post
    I usually fly the default 747 vc. In that an ils gives distance info. (on the hsi).
    So I think ils gives distance, ils is always a combi of localiser and dme I think.
    How else to know when to start the descent? Can't if no distance is known.

    If you don't see the dme info in your 'hsi', then fixing may be more of a matter of finding a usefull gauge.
    Or of using one that is in the aircraft already. On the default pros plane radio gauge (bendix?) is a distance info option. You can switch that to nav2 or nav1 distance. Try that.
    (not at pc a.t.m. Or I would try myself first.)
    Nope -- not all ILSs have DME -- DME is a separate installation that may or may not be present.

    "ils is always a combi of localiser and dme I think. " should be "ils is always a combi of localiser and glideslope.

    On an ILS, you start your descent when you intercept the glideslope, but in any case (even with LOC only), you descend after the FAF (the GPQ NDB in this case), which is ALWAYS present on an instrument approach. Distance has nothing to do with it, in terms of when to start, unless it is specified as part of the approach itself (basically, as the FAF).

    A "useful gauge" can't display what's not available. Take a look at the approach plate for the specific ILS/airport that the OP specified: KCTJ, here. Find any DME on that plate other than on the LAGRANGE VOR.

    On ANY instrument approach, it is only legal to use DME as a defining part of the approach when it is specifically specified on the approach plate. IF a DME is available, it can be used as supplementary information when not actually part of the approach definition, but may not legally be used for defining the approach.

    Do what you like in the sim, but note that the above is part of why it takes a lot of ground time, as well as flying time, to get an instrument ticket in the real world -- there's a LOT to learn, and much (most?) of it is NOT intuitive. And please don't teach others the wrong information. I used to teach this stuff, and even though that's almost 20 years in the past, not that much has changed, and certainly not that.

    Addendum: Page 10-13 of the FAA's Instrument Flying Handbook starts the section on instrument approaches. There are 371 pages in this PDF, and they cover regs, weather, procedures, theory and much more. The section on approaches goes through 10-22, where Instrument Weather Flying starts.
    Last edited by lnuss; 03-14-2018 at 12:59 PM.

    Larry N.

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

  8. Default

    Of course, glideslope antenna, no dme needed, must have not had coffee yet.
    But didn't know that there are ils without dme. Good to know.

  9. Default

    Thanks all.

    So, I planned a flight from KCTJ to KJAX. FSX advised me to fly towards VNA (116.5) and then on to AMG (115.10).

    I put VNA on NAV1 and AMG on NAV2. I set my bug to 140 and ALT to 5K and take off. I get into a stable flight and then arm NAV.

    The first thing I noticed is that I can't actually "see" VNA. No worries, I'll just head that way and see what happens.

    Well, NAV2 sprang to life shortly after. I confirmed the DME reading of 167NM. Still nothing on NAV1.

    After some time, I start to question what I'm seeing/doing. Still no NAV1. I've checked and double-checked frequencies. Now I'm checking the in-game map. Still nothing.

    Finally, NAV1 springs to life. At 60NM on the DME!

    Do they change the power on these things?

    What's the point of a flight plan where I can't see the first step after takeoff?

    I'll be so glad when they invent some more reliable method of navigation...

  10. #10
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    Well, NAV2 sprang to life shortly after. I confirmed the DME reading of 167NM. Still nothing on NAV1.
    You're unlikely to ever see that in the real world, rarely more than 60-80 NM.

    What's the point of a flight plan where I can't see the first step after takeoff?
    First, pilots are responsible for their own flight planning -- ATC doesn't do that for you. It's the pilot's responsibility to ensure that there are usable navaids where needed. You could have flown outbound from the NDB (using the ADF, of course) until getting in range of VNA. Otherwise you can look into other available VORs. This is one big reason that pilots use charts to plan flights.

    When VFR, some folks may do as you did, but when IFR that isn't viable, normally, so you can sometimes have some odd routing in order to stay within range of needed navaids.

    Alternatively, you could use the GPS.

    Larry N.

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

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