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Navigation Questions

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    Navigation Questions

    Ok, so I'm a newb to sims (at least REAL sims like this one). I'm slowly starting to get the hang of things. Right now I'm focusing on navigation. I've run the training mission 3 times now and am using the manual as a reference. I'm also doing some "training" on my own by flying around the instant action missions, just inputting waypoints and using different system.

    I'm just looking for some clarification on some questions that I can't seem to find answers for. (The manual is a bit muddled on them)

    Using EGI navigation there are the 4 steering methods methods:

    From the manual:
    Steering modes include:
    o TO FROM: The set course uses the great circle path along the course entered with the course set knob on the HSI to and from the selected steerpoint.
    o DIRECT: The set course uses the great circle path from the aircraft's current position at the time the DIRECT mode is selected to the selected steerpoint. Each time you select a new steerpoint, a course is computed from the aircraft's current position to the new steerpoint.
    o TO TO: The set course uses the great circle path from the set From point as displayed on the CDU FROM page to the selected steerpoint.
    o SCS: Selected Course Steering (SCS) uses the manually set course away from the aircraft's current position when SCS is selected. SCS cannot be selected when ANCHR is selected from the Navigation Mode Select Panel.

    Direct is obvious, it's the other 3 that are giving me some trouble. TO FROM seems like it should be the standard method of navigation you'd find in civil availtion. (Set HSI to radial you want to fly, follow CDI needle, etc.) right? TO TO is just a mode where the computer tells you what to set the HSI to in order to follow your flight plan? And can someone explain SCS to me, and what the LSK9 ON/OFF toggle does. I know that it effects my CDI/HSI, but I'm having quite a time trying to figure it out.

    Also, you can set these 4 option on both the ATTRIBUTES page, and the FPL Editing page, but the values don't seem linked. What is the difference? Is there a difference.

    Finally, (an it could be because I'm not quite sure how to set up the TO TO navigation,) it seems like my HSI and pitch indicator are backwards. i.e. If I actually try and fly towards the CDI needle it actually is taking me away from the FPL line on the TAD. However as fly away from the CDI needle (towards the FPL line) the needle centers. It seems like there could be a TO/FROM setting somewhere that I'm missing, as in civil av if you set the VOR on the opposite radial, the needles act in reverse. That's how I'm rationalizing it anyway.(This is evident in the training mission during the TO TO portion of the training (WPT 3 to 4 I believe). Any ideas on what's causing this/how to correct it?

    I know the questions are long, (and probably confusing) so please ask for clarification if I'm not making sense.

    Thanks to everyone in advance.

    I haven't flown the training mission myself, so if there's a specific issue or problem you're having with it, let me/us know so it can be properly addressed. Otherwise, we'll jump right in...

    DIRECT is indeed fairly straight forward. It draws a Great Circle line between the EGI position at the time of mode engagement, and the selected steerpoint. The CDU will display the magnetic course that must be set via the HSI CRS knob in order to obtain proper CDI indications. The HSI will then provide raw course deviation data.

    TO TO mode is nearly identical in function, except instead of using EGI Present Position as the "from" waypoint, you specify an actual named waypoint to navigate from via the CDU FROM page. The FROM waypoint can be entered by name, or by entering its ID number. As before, the CDU will display the magnetic course that should be set on the HSI CRS knob.

    TO FROM mode is a little bit different. It only uses a single "to" steerpoint, and draws the Great Circle line through that point according to the value you set via the HSI CRS knob. This mode behaves exactly as if you were navigating with a conventional VOR. As you spin the HSI CRS knob, you're selecting the desired inbound course, and the CDI will deflect as appropriate.

    SCS mode is like TO FROM mode in reverse. In this case, you're defining your EGI Present Position as the "from" from waypoint, then you specify the desired outbound course from that point using the HSI CRS knob.

    You mention reverse sensing in some cases, but since I haven't flown the mission in question, I'm not sure of the cause. Your gut instinct is probably correct though, try setting the reciprocal course on the HSI, and you should regain correct sensing.

    Regarding the waypoint attributes, the ATTRIBUTES page contains the default attributes that will be assigned to all waypoints created in the FPBUILD page, and to any waypoints that didn't have data uploaded from the DTS (not applicable to this simulator).

    If you want to change the attributes of a MISSION or MARK point, you may do so from the WAYPT page. FLT PLAN points can be changed from the WPTATT page.

    I'm not sure what you mean about LSK9? Can you clarify?




        Thanks for the replies

        Fredrerf: Those were some heated discussions RE: backwards HSI's. I've essentially come to similar conclusions regarding flexibility in FLT PLAN mode. It seems far easier to set to Mission and go from there as everything makes sense in mission mode. However, I assume that FLT PLAN mode will have it's advantages in actual missions, so: In your experience did you ever come to a conclusion in FLT PLAN mode as to whether the HSI is modeled correctly?

        BlueRidge: LSK9 Line select key 9, I forgot to specify left. I figured out what it does though. It just turns the SCS ON/OFF (now that I understand what SCS is actually doing.

        The concusions that I've come to are that you use the WPT INFO page if your in MISSION or MARK mode, and you have to actually go to the FPM menu if you want to make any changes in FLT PLAN mode.

        Other than that it's jsut the (seemingly) backwards HSI in FLT PLAN mode that still has me stumped. Obviously there is way more depth which I'll probably have to start getting into once I start flying mission where ordnance are being released.

        I'm sure you'll hear from me again.

        Thanks again everyone.


          FLT PLN is the only mode that allows automatic advancing of points, lines between points on the TAD, and probably some other features. Its "ineditability" is a feature more than a hindrance. When you make the original flight plan you sort out what attributes you want for each waypoint and don't want them accidentally changed. It is possible to edit these values, you just have to do it through the FSBuild thingy.

          As much as I've learned and observed about the CDU navigation and the HSI, I haven't seen a single instance of something I can confidently say is modeled incorrectly. I haven't learned or observed everything so there might be some mis-modelings in there somewhere.

          There is a TO/FROM flag on the HSI, just as in civvy VOR-NAV instruments. In TO-TO you have to manually crank the CRS to the proper value of course between the FROM PT to the STPT. In TO-FROM you have to have the "TO" flag showing to get non-reversed needle steering.

          The one I'm suspicious of is SCS with regards to reverse steering. You turn on SCS, set CRS 090 and see the line from the SCS origin out to the east. However as you fly out along the TAD line (to the east) one finds the CDI reverse senses. I can't get any normal CDI sensing more matter which combination of course, reciprocal, inbound, or outbound I try.


            Yeah, in SCS with a FROM flag and the CRS knob on the desired outbound course, the CDI should be in the correct sense but it presently isn't.

            There's also an issue where the CDU FROM page should only be active/editable in TO TO mode, but it's presently active in TO FROM as well. So the system is expecting a FROM waypoint in TO FROM mode, which isn't correct.

            This is also causing the ATTRIB page to incorrectly display DIAL HSI TO CRS: hhhh" in TO FROM mode. It should display "HSI SET AT CRS: hhhh" instead, since TO FROM mode is driven by the HSI CRS knob.

            I've been refraining from reporting any of this kind of stuff though, since the general consensus seems to be that the official testers don't want the feedback. At some point it's going to be too late to report this kind of thing, so it's a "damned if you do, damned if you don't" situation.