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Programming outbound track in FMS

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woody View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote woody Quote  Post ReplyReply Direct Link To This Post Topic: Programming outbound track in FMS
    Posted: 27 Jul 2018 at 6:51pm
so another avidyne user and I were discussing this the other day - if given an ATC instruction to ‘fly outbound on track xxx degrees gnss’, what is the easiest way to accomplish this on the IFD? I have just used the OBS function after a ‘direct to’ the origin airport and the course set to the instructed track, and flown outbound on the magenta line, but is there a way to enter an outbound track from the origin airport in the FMS?

Thanks, Martin
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Post Options Post Options   Thanks (0) Thanks(0)   Quote oskrypuch Quote  Post ReplyReply Direct Link To This Post Posted: 27 Jul 2018 at 8:09pm
Only alternative to OBS, is to create a user waypoint in the right spot. All GPS tracks are defined as from a waypoint, to another.

I have made a suggestion which would make creating such a waypoint very quick, but until that is implemented (if it ever is), you need to use the user waypoint dialog.
 

* Orest



Edited by oskrypuch - 29 Jul 2018 at 12:19am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DH82FLYER Quote  Post ReplyReply Direct Link To This Post Posted: 27 Jul 2018 at 9:07pm
Yes, adding a new waypoint based on a radial and distance, requires a lot of button pushes and knob spinning in what could be a high workload environment. 
The ability to set up a ‘pretend VOR’ from your departure point would be very useful to enable such outbound radials.
A feature for 10.3?

Thomas


Edited by DH82FLYER - 27 Jul 2018 at 9:24pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DH82FLYER Quote  Post ReplyReply Direct Link To This Post Posted: 27 Jul 2018 at 10:19pm
On further thought, the ability to set up a ‘pretend VOR’ at any waypoint (not just the current active “to” waypoint). This would be a neat feature, especially in view that VORs are being closed down around the world. 

Thomas


Edited by DH82FLYER - 27 Jul 2018 at 11:59pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote woody Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jul 2018 at 2:45am
I guess the OBS feature does a pretty good job of emulating a VOR for en route and destination wpts, but it is less intuitive for a track to be flown from the departure airport where no Navaid exists. It would be good to have the feature in the FMS to plan an initial outbound track that is not in the flight plan or in a SID, when the occasion arises. In my case I received a last minute revised clearance whilst lined up at the departure threshold, ‘fly xxx track outbound gnss until advised’ which resulted in lots of frantic button pushing and OBS-ing. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kgrant Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jul 2018 at 8:08am
I studied that a lot. A couple of airport I frequent are in airspace where the departure clearance includes a heading to intercept a VOR radial......  

Takes some thinking ahead of time but:

AFTER pushing "Activate Flight Plan"...
select direct to your departure airport ... (which appears on the flight plan page)
push the Nav Source knob in to activate OBS ...
dial in the outbound course.

If the leg you intend to intercept is in front of you (displaying on the map) you'll see it work.

I do a proficiency flight frequently where I depart my home airport and intecept a DME arc about 3 miles north of my departure airport.  It took me several tries and trips back to the Pilot Guide to figure out why my autopilot would fly right through it. You have to have a waypoint in your flight plan to generate the OBS outbound.  When you think about it though -- it makes sense. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bob H Quote  Post ReplyReply Direct Link To This Post Posted: 30 Jul 2018 at 9:30am
Quote I studied that a lot. A couple of airport I frequent are in airspace where the departure clearance includes a heading to intercept a VOR radial......Takes some thinking ahead of time but:
AFTER pushing "Activate Flight Plan"...select direct to your departure airport ... (which appears on the flight plan page), push the Nav Source knob in to activate OBS ... dial in the outbound course.
There is the tendency to try to program EVERYTHING into the GPS Box.  While it is a good exercise for learning when on the ground, it is not always necessary or efficient to do so during departure or in the air.  Sometimes just using raw data and flying the plane is the best course of action.  If I had the above clearance, I would simply fly the heading and intercept the VOR radial.  Besides, flying a track is not flying a heading.  If the controller gives you a heading to fly, that is what you should do.  If the radial for intercept is a segment of your flight plan, you should activate that leg and intercept on the given heading.  No, OBS manipulation necessary.  Much of the time the “fly heading” comes as part of the take off clearance.  That is not the time to start button pushing.  Just fly the plane as instructed.  Simple.
Quote if given an ATC instruction to ‘fly outbound on track xxx degrees gnss’, what is the easiest way to accomplish this on the IFD? I have just used the OBS function after a ‘direct to’ the origin airport and the course set to the instructed track, and flown outbound on the magenta line, but is there a way to enter an outbound track from the origin airport in the FMS?
From my perspective, “the easiest way to accomplish this on the IFD”, is to fly a track on the IFD just like you would a heading with the DG.  It isn’t necessary to have a magenta line in order to fly a track.  If you want the magenta line, then the OBS method you describe is the only way to go.
Quote Yes, adding a new waypoint based on a radial and distance, requires a lot of button pushes and knob spinning in what could be a high workload environment. 
The ability to set up a ‘pretend VOR’ from your departure point would be very useful to enable such outbound radials.
A feature for 10.3?
Please help me understand what is being asked for here.  If we are flying by reference to waypoints, we already have the ability to treat them as pseudo VORs by using OBS mode.  If a new point in space is desired that is not already defined, we still need to define where the pseudo VOR will be located.  Perhaps what is really being asked for is a simple and quick way to define waypoints per Orest’s post above, not pseudo VORs.

Bob
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kgrant Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jul 2018 at 7:45am
Originally posted by Bob H Bob H wrote:

Quote I studied that a lot. A couple of airport I frequent are in airspace where the departure clearance includes a heading to intercept a VOR radial......Takes some thinking ahead of time but:
AFTER pushing "Activate Flight Plan"...select direct to your departure airport ... (which appears on the flight plan page), push the Nav Source knob in to activate OBS ... dial in the outbound course.
There is the tendency to try to program EVERYTHING into the GPS Box.  While it is a good exercise for learning when on the ground, it is not always necessary or efficient to do so during departure or in the air.  Sometimes just using raw data and flying the plane is the best course of action.  If I had the above clearance, I would simply fly the heading and intercept the VOR radial.  Besides, flying a track is not flying a heading.  If the controller gives you a heading to fly, that is what you should do.  If the radial for intercept is a segment of your flight plan, you should activate that leg and intercept on the given heading.  No, OBS manipulation necessary.  Much of the time the “fly heading” comes as part of the take off clearance.  That is not the time to start button pushing.  Just fly the plane as instructed.  Simple.

I get your point but you missed the major part of mine.. 

If your flight plan first leg is a DME arc and you want to INTECEPT it without flying to the end of it -- you have to get the box to recognize you have intercepted it.  

You HAVE to do that with an OBS outbound track that intercepts the arc. (which requires a waypoint or the departure airport.)  I you you fly an assigned heading THROUGH the arc -- it never recognizes it. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bob H Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jul 2018 at 9:07am

Originally posted by kgrant kgrant wrote:

I get your point but you missed the major part of mine..If your flight plan first leg is a DME arc and you want to INTECEPT it without flying to the end of it -- you have to get the box to recognize you have intercepted it.You HAVE to do that with an OBS outbound track that intercepts the arc. (which requires a waypoint or the departure airport.)  I you you fly an assigned heading THROUGH the arc -- it never recognizes it.
No, I didn’t miss your point.  Quite the contrary.  I was simply pointing out that sometimes flying the airplane with raw data is the best course of action.  Not always, but sometimes.  It’s simply an alternate option to consider in lieu of programming the box.  You use statements such as “HAVE to do” and “requires a waypoint or the departure airport” or “fly an assigned heading THROUGH the arc”.  This all implies that flying a heading and intercepting a DME arc is not possible without programming the box.  This is just not the case.  Raw data can be used to do that as well.  We all have the tendency to want to program the GPS to do everything we want – me included.  There are situations where I must stop myself from programming the box and just fly the airplane.  We all just need to recognize this tendency and not be a slave to it.  Check out this video to see my point:  https://www.youtube.com/watch?v=pN41LvuSz10

Bob
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 94S Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jul 2018 at 1:05pm
Bob, that is a very good point about not being a slave to the box, but I think you missed a key point in the original post.  

The OP wrote, "...given an ATC instruction to ‘fly outbound on track xxx degrees gnss’" (emphasis added).  I've never heard that instruction here in the US, but it must be a thing in other parts of the world and maybe is here and I've just not heard it.  The OP is in Australia.  If my interpretation of that instruction is correct, ATC is not asking for heading to be flown but a GPS derived track.  In which case you would need to program the box to fly the track.

That being said, isn't possible to use the Origin airport as an anchor for OBS? I haven't had a chance to play with this on the simulator.  Or could this instruction be given at non-waypoint points any were throughout the flight?

David
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Post Options Post Options   Thanks (0) Thanks(0)   Quote HenryM Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jul 2018 at 1:21pm
My IFD-540 displays the current track right at the top of the map page. Wouldn't you just look at that number and be sure it is what the instruction says? No magenta lines, no fumbling with knobs. If you have the DME arc already programmed, you could activate that leg once you got to it, no? 

The main reason I see for wanting to add the instruction to the flight plan is to let an autopilot fly it. Otherwise, a few minutes of hand flying should work. Even on autopilot, I'd put my STEC-30 in HDG mode and set my DG accordingly. I'd watch it to make sure that the track displayed by the IFD matched the instruction.

Note I'm a relative newby with my IFD-540. I may not be understanding all the implications of not programming in that first instruction.


Edited by HenryM - 31 Jul 2018 at 4:27pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bob H Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jul 2018 at 2:35pm
Originally posted by 94S 94S wrote:

Bob, that is a very good point about not being a slave to the box, but I think you missed a key point in the original post.
The OP wrote, "...given an ATC instruction to ‘fly outbound on track xxx degrees gnss’" (emphasis added).  I've never heard that instruction here in the US, but it must be a thing in other parts of the world and maybe is here and I've just not heard it.  The OP is in Australia.  If my interpretation of that instruction is correct, ATC is not asking for heading to be flown but a GPS derived track.  In which case you would need to program the box to fly the track.
That being said, isn't possible to use the Origin airport as an anchor for OBS? I haven't had a chance to play with this on the simulator.  Or could this instruction be given at non-waypoint points any were throughout the flight?

David
Hi David,
I broke out quotes in my first post to address several different posited scenarios.

1. Kgrant wrote: “…departure clearance includes a heading to intercept a VOR radial…[& DME Arc]…”
2. Woody wrote: ‘fly outbound on track xxx degrees gnss’
One is a heading.  The other is a track.
I addressed Kgrant’s scenario in my first quote and Woody’s in my second.
In response to Woody, I stated: “…fly a track on the IFD just like you would a heading with the DG.  It isn’t necessary to have a magenta line in order to fly a track….”

So, it isn’t necessary to program the GPS to fly a track, UNLESS you want a magenta line or the autopilot to fly the course.  And, yes, if you decide to program the track, you can use the Origin and OBS mode.

The urge to program the GPS is so strong, for me as well, it sometimes feels that the only way to fly a course is via programming.  Both you and Kgrant responded to me by saying that “you need to” or “must” program the GPS, when in reality you don’t.  You can choose to just fly the required course using raw data, and there are times when that is the best option.  This applies equally to Track, Radials, DME Arcs, etc.  Please don’t take any of this personal.  I am not being critical.  I am making observations about how WE as pilots interact with and use our GPSs.  It’s the old adage “When all you’ve got is a hammer, everything looks like nail”.  There are other tools in our tool chest, but sometimes we forget that they’re there when they may just be the best option.  ME included.  Once on the ground, I will often ask myself, how could I have programmed that if I had wanted to.  That is a great way to learn the subtleties of the GPS in the comfort of your living room.


Edited by Bob H - 31 Jul 2018 at 4:17pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bob H Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jul 2018 at 3:52pm
Originally posted by HenryM HenryM wrote:

My IFD-540 displays the current track right at the top of the map page. Wouldn't you just look at that number and be sure it is what the instruction says? No magenta lines, no fumbling with knobs. If you have the DME arc already programmed, you could activate that leg once you got to it, no? 

The main reason I see for wanting to add the instruction to the flight plan is to let an autopilot fly it. Otherwise, a few minutes of hand flying should work. Even on autopilot, I'd put my STEC-30 in HDG mode and set my DG accordingly. I'd watch it to make sure that the track displayed by the IFD matched the instruction.
Yes, indeed!  Exactly my point.
Bob
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 94S Quote  Post ReplyReply Direct Link To This Post Posted: 01 Aug 2018 at 10:11am
Bob,

Thanks.  It wasn't until I read HenryM's post that your earlier post made sense.  I'd never thought of using the Trk displayed on the IFD for any practical navigation use.  I've only ever needed the DG or CDIs for guidance in the flying that I've done.   But then again I've never heard a "fly track" instruction either.  But now when I do, I'll know how to make that happen.

David
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bob H Quote  Post ReplyReply Direct Link To This Post Posted: 01 Aug 2018 at 10:25am
Clarity is not always my strong suit!
Bob
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kgrant Quote  Post ReplyReply Direct Link To This Post Posted: 01 Aug 2018 at 11:19pm
I think you need to go intercept a DME arc and see what it does. k
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bob H Quote  Post ReplyReply Direct Link To This Post Posted: 02 Aug 2018 at 8:01am
Originally posted by kgrant kgrant wrote:

I think you need to go intercept a DME arc and see what it does. k
I'm not invalidating or disagreeing with anything that you are saying.  I am only trying to make the point that in some circumstances the best course of action is to simply turn the plane manually to intercept the DME Arc rather than programming the GPS.  When you found yourself flying through the DME Arc, did you not do that?  DME Arcs existed long before GPS and we managed to fly them just fine using just DME and VOR information, which is what I mean by raw data.  So, there are times when it is prudent to do just that.  It is admirable that you spent the time to read the manual and work out how to program the DME Arc intercept into the GPS.  That is how we all become more adept at using the IFD.  But, there are circumstances where, even when we know how to program the GPS, that it is best to ignore the GPS and just fly the clearance using other methods.  In other words, don't worry about what "IT" does, but rather what "YOU" do.  Sorry that my posts have not been clear.

Edited by Bob H - 02 Aug 2018 at 8:05am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rolfe_tessem Quote  Post ReplyReply Direct Link To This Post Posted: 04 Aug 2018 at 10:58am
Maybe I don't understand the problem, but don't you just use the activate leg feature a couple of miles before you intercept the arc? The arc leg should turn magenta and the autopilot should intercept it.

Rolfe

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Post Options Post Options   Thanks (0) Thanks(0)   Quote kgrant Quote  Post ReplyReply Direct Link To This Post Posted: 05 Aug 2018 at 2:01pm
The problem is that the FMS doesn't display the arc itself as a leg. You can select the fix at either end of the arc -- but if you fly a track that intercepts the arc -- it doesn't recognize it.

I first caught it when cleared to join a dme arc for an ILS approach at SLN.  As soon as I recognized that it wasn't going to capture, I hand-flew it.

Since then I've tried multiple times to figure out how to configure it.  I assumed I was setting it up wrong, but I haven't found a solution -- only a "workaround".

If you have a flight plan in the FMS, select procedure and the initial fix of an arc for the transition -- you'll need to establish an OBS heading prior to your last fix if you are intercepting or fly the complete arc.

I hate to mention it -- but my 430W displays the arc as a leg.  Simply select it and hit direct.  It intercepts and flies it from your present position.   
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rolfe_tessem Quote  Post ReplyReply Direct Link To This Post Posted: 06 Aug 2018 at 9:05am
Originally posted by kgrant kgrant wrote:

The problem is that the FMS doesn't display the arc itself as a leg. You can select the fix at either end of the arc -- but if you fly a track that intercepts the arc -- it doesn't recognize it.

I first caught it when cleared to join a dme arc for an ILS approach at SLN.  As soon as I recognized that it wasn't going to capture, I hand-flew it.

Since then I've tried multiple times to figure out how to configure it.  I assumed I was setting it up wrong, but I haven't found a solution -- only a "workaround".

If you have a flight plan in the FMS, select procedure and the initial fix of an arc for the transition -- you'll need to establish an OBS heading prior to your last fix if you are intercepting or fly the complete arc.

I hate to mention it -- but my 430W displays the arc as a leg.  Simply select it and hit direct.  It intercepts and flies it from your present position.   

I have no DME arc approaches around me to try for real (probably a good thing)...

But, according to Michael Bauer's book on flying with the IFD, you select the VORDME approach and the arc should appear as a transition, which you also select. That puts the arc in the flight plan, from where it can be chosen and the activate leg selected just before you intercept it.

Does this really not work as he outlines in the book?

Rolfe

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Post Options Post Options   Thanks (0) Thanks(0)   Quote kgrant Quote  Post ReplyReply Direct Link To This Post Posted: 07 Aug 2018 at 7:16am
It allows you to select the ends of the arc but not the arc itself.  That's the issue. It sequences to the next waypoint rather than tracking the arc.  The FMS displays the outer ends and the inbound terminating waypoints.  You can't select the arc itself. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote HenryM Quote  Post ReplyReply Direct Link To This Post Posted: 07 Aug 2018 at 11:47am
I was playing around with the scenario on the simulator. 

To set up the scenario, I had to use a trick mentioned above and entered the departing airport a second time, after using it as the origin. This let me set an OBS course 'from"the airport to get me heading towards the DME arc at KSLN. 

The flight plan was then KCNK -> KCNK -> KSLN with the ILS 35 approach, Zomon IAF, that has the DME arc.

After departing, I selected direct to the second instance of KCNK and clicked the CDI/OBS button to activate OBS mode. I then quickly turned the knob to set a track at around 161º.

The interesting thing is that that track automatically set a turn into the DME arc where it intersected it as shown in the picture below. I let the simulation continue, and the plane turns into the DME arc and then the rest of the flight plan is followed. The only thing missing is the barber pole indication that it will continue with the DME arc.

I the re-ran the scenario, but about 2.5 nm before reaching the arc, I clicked on the D170W Waypoint with the 23DME R arc notation and hit the Activate Leg LSK. The OBS track disappeared and the plane just started turning to intercept the arc, fly along the arc, and then fly the rest of the flight plan as entered. 

You can't select D170W and click Direct To, because that will just get you going straight to the waypoint. However selecting the waypoint and activating the leg seems to work.

I can sort of see how put an OBS marker at my current location would be useful. However, in my flying in the US, I've only been given headings to fly, and in that case, I just hand fly the heading or set the autopilot to use the DG and not the GPS. I assume getting close to the DME arc and activating that leg should get things going again for the autopilot, as long as I remember to switch back to GPSS mode. I don't know of any DME arcs to fly nearby so I can't try this out for real.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bob H Quote  Post ReplyReply Direct Link To This Post Posted: 07 Aug 2018 at 7:19pm
I get the same behavior as Henry on the sim for both KSLN and another DME Arc approach.  On the sim, activating the DME arc leg always results in a magenta arc, next leg barber pole, and an intercept of the arc.  I don't understand "direct to" for activating a leg since the "Activate Leg" LSK or touchscreen must be used not "direct to".  IF the IFD in flight behaves as the Sim does, then it appears to behave normally when activating a DME Arc leg.  However, it is an anomaly to me that the OBS course discontinues at the DME arc and the arc is intercepted without that leg being activated.  If I have selected an OBS course, the IFD should continue to fly it until told otherwise.   However, at this point, I can't confirm if the sim and in-flight IFD behave identically.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rolfe_tessem Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 2018 at 3:11pm
The example above works for me in the sim as well. Interestingly, the example given in Bauer’s book, the VORDME22 at KHUT doesn’t seem to be in my database. 

As the book does note, when you activate the leg, the plane will immediately turn to intercept the arc at a tangent angle, so you don’t want to activate it too early...

Rolfe
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Post Options Post Options   Thanks (0) Thanks(0)   Quote HenryM Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 2018 at 3:33pm
I just tried entering the KHUT approach in my simulator, and it is there, including the DME arc from ZYMEX. I had cycle 1808 Nav Data loaded. I then noticed cycle 1809 was available and tried it. The approach is also included. Maybe you have an older database?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rolfe_tessem Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 2018 at 3:43pm
KHUT worked once I had the correct IAF selected :-).l

The screenshots in Bauer’s book are slightly different — looks as though a few things changed in 10.2.

Rolfe


Edited by rolfe_tessem - 08 Aug 2018 at 3:45pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kgrant Quote  Post ReplyReply Direct Link To This Post Posted: 11 Aug 2018 at 7:58am
Originally posted by HenryM HenryM wrote:

....

The interesting thing is that that track automatically set a turn into the DME arc where it intersected it as shown in the picture below. I let the simulation continue, and the plane turns into the DME arc and then the rest of the flight plan is followed. The only thing missing is the barber pole indication that it will continue with the DME arc.

I the re-ran the scenario, but about 2.5 nm before reaching the arc, I clicked on the D170W Waypoint with the 23DME R arc notation and hit the Activate Leg LSK. The OBS track disappeared and the plane just started turning to intercept the arc, fly along the arc, and then fly the rest of the flight plan as entered. 

You can't select D170W and click Direct To, because that will just get you going straight to the waypoint. However selecting the waypoint and activating the leg seems to work.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote kgrant Quote  Post ReplyReply Direct Link To This Post Posted: 11 Aug 2018 at 8:10am
Sorry I've been "offline"  a few days here.  I'll have to try that in the airplane. I've got a DME arc just a few miles from my home airport for an adjacent airports' VOR approach.  In all my my attempts, I've set the OBS "from" to intercept a point on the arc and it flies right through it without capturing.  

When I "activate approach",  the initial leg is the end waypoint on the arc. The box behaves as if the the waypoints are a direct line rather than an arc. (you can choose direct to either end but not the arc) Maybe I'm missing the "activate leg" LSK....

I haven't done as you suggest and try to manually sequence it close to the arc.  In the POH, it reads that an OBS "from" will automatically sequence when it intercepts the active flight plan. Maybe it treats an approach segment differently. k


Edited by kgrant - 11 Aug 2018 at 8:13am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rolfe_tessem Quote  Post ReplyReply Direct Link To This Post Posted: 11 Aug 2018 at 9:04am
Has anyone actually gotten a clearance that required an actual "track" to intercept something like a DME ARC? In all my years of flying, I can only recall being given a heading. This is in the US -- maybe other parts of the world are different...

Rolfe



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Post Options Post Options   Thanks (0) Thanks(0)   Quote kgrant Quote  Post ReplyReply Direct Link To This Post Posted: 11 Aug 2018 at 10:53pm
We get a vector to intercept frequently at Springfield.  I got one at Salina which got me trying to figure out how to make it work.  Not sure we would ever get a "track". k
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bob H Quote  Post ReplyReply Direct Link To This Post Posted: 12 Aug 2018 at 11:17pm

Originally posted by Bob H Bob H wrote:

However, it is an anomaly to me that the OBS course discontinues at the DME arc and the arc is intercepted without that leg being activated.  If I have selected an OBS course, the IFD should continue to fly it until told otherwise.
Think I’ll change my mind about this.  As kgrant pointed out, this behavior is documented in the PG and since the OBS track is part of a flight plan, it makes sense that the IFD should transition to the next leg that it intercepts. 

I continued to play around with the sim, and an OBS track always intercepts the DME Arc.   During intercept, the arc always turns magenta, but as Henry pointed out, never the barber pole prior to the intercept.  So, the sim at least, behaves as expected and documented, except maybe for the barber pole, but with the curved track in there, it is telegraphing the next leg, so I’m ok either way. 

Below are a couple of photos showing the OBS track to the DME Arc and the intercept with DME Arc change to magenta and reverting back to GPS mode.


Bob
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kgrant Quote  Post ReplyReply Direct Link To This Post Posted: 18 Aug 2018 at 10:00pm
So after a flight today, (thanks Jeff!) I think I got this DME arc intercept figured out.  As mentioned here -- the "Activate Leg" FSK works once I figured out what leg to activate!  

I was trying to activate the initial leg which commences at the outer end of the arc.  My head couldn't wrap around the reason the arc was the barber pole -- but wouldn't sequence. 

Before reaching the arc, I selected THE NEXT waypoint  (AFTER the arc) and then press "Activate Leg". Whal-la -- I get a pink arc.

Now when this thread started -- it was about getting an OBS outbound bearing to join the arc. I've gotten that to work by creating a waypoint at present position and dialing in the obs "from" to a point that joins the arc. Of course, as pointed out here -- a vector accomplishes the same. 

All good stuff to maintain proficiency with the "box".k


Edited by kgrant - 18 Aug 2018 at 10:02pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bob H Quote  Post ReplyReply Direct Link To This Post Posted: 19 Aug 2018 at 10:05pm
Originally posted by kgrant kgrant wrote:

So after a flight today, (thanks Jeff!) I think I got this DME arc intercept figured out.  As mentioned here -- the "Activate Leg" FSK works once I figured out what leg to activate!  

I was trying to activate the initial leg which commences at the outer end of the arc.  My head couldn't wrap around the reason the arc was the barber pole -- but wouldn't sequence. 

Before reaching the arc, I selected THE NEXT waypoint  (AFTER the arc) and then press "Activate Leg". Whal-la -- I get a pink arc.

Now when this thread started -- it was about getting an OBS outbound bearing to join the arc. I've gotten that to work by creating a waypoint at present position and dialing in the obs "from" to a point that joins the arc. Of course, as pointed out here -- a vector accomplishes the same. 

All good stuff to maintain proficiency with the "box".k
Excuse me if I get overly simplistic here.  But how we think about the IFD architecture and the nomenclature is important for using it and making it intuitive.  The language “…I selected THE NEXT waypoint (AFTER the arc)…” makes it sound counterintuitive that to select a leg you must select the waypoint AFTER the leg you want.  Since a leg is made up of two waypoints, one at the end and one at the beginning, it could appear arbitrary that Avidyne chose the waypoint at the end of the leg rather than the beginning.  But it certainly isn’t.  Perhaps Garmin habits get in the way of how the IFD works and shifting one’s “GPS thinking”.

The FP is only made up of waypoints, not legs.  You can’t select a leg.  You can only work with waypoints.  When on a FP the IFD is ALWAYS telling us TO where we are going, never FROM (ignore OBS as not relevant to a FP).  When we activate a waypoint, we are asking to be taken TO the waypoint.  So, when wanting to fly a specific leg (arc or not), the first step is to program the IFD to go TO a waypoint, the next step is HOW to get there.  The HOW are Direct or FP Leg.  Based on this, it ONLY makes sense to use the waypoint at the end of the leg we are trying to fly TO, not the waypoint we are flying away from.  It is out of sequence to want to activate a leg before defining where you want TO go.  And you certainly don’t want to fly a leg based on a waypoint that you have no intention of flying to.  So, I don’t care how a leg or arc is defined or what waypoints come before or after.  All I need to decide is where I am headed next.  Simple and intuitive.  And fortunately for me, it takes zero brain power.  If I had to think about what “…THE NEXT waypoint (AFTER the arc)…” was, I’d get my shorts in a knot.  Again, sorry if this is overly simplistic, but I wanted to give a more intuitive way to think about the IFD architecture when selecting a leg.

Bob
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