Localizer Approach, CDI & OBS

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apr911

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apr911
So I've finally started my instrument training and I've decided to go 141 for it because I want to be thorough but get through it "quick" which is to say I dont want to spend days/weeks between flights coordinating with my instructor for availability. 141 gives me access to a full-time instructor so I dont have conflicts with my instructor's day job.

Being new to IFR, I'm obviously looking to my instructors for instruction and know my own knowledge may be incorrect. That being said, I've had 2 instructors now both tell me the same thing that I believe to be incorrect regarding a localizer approach...

They've both told my my OBS has to be set to the runway heading for the localizer. This is contrary to my own interpretation of how the localizer works: That being a directed signal that is always broadcasting the same "message" unlike a VOR that broadcasts one signal a "message" for "north" and a second "message" for "bearing" that moves at a constant rate from heading 0 to 360 which the nav radio interprets the time between the "north" signal and "bearing" signal to calculate the correct radial you are following.

It is also contrary to my own experience: I've flown the localizer before albeit not in instrument conditions/under the hood and using an HSI instead of a VOR/CDI and I know I didnt change the OBS and I am fairly certain the OBS heading was not set to the runway though the Localizer worked just fine...

It's my contention that if the Runway heading is 270 and I set my OBS to anything other than 270, my CDI needle will still be accurate as it disregards the OBS and only tracks the 270 course to the runway. Its also therefore my contention that it is impossible to reverse sense a localizer when flying TO it (I know many in the Localizers in the US broadcast in both directions such that flying through the localize will give you reverse sensing but flying to the airport gives you a non-precision approach to the opposite runway using the Localizer backtrack)

So while I know its a good practice to set the OBS to be in agreement with your actual heading, especially when flying instruments, I dont believe the information my instructors have given is correct. I plan to test my theory the next time I go up but its been a question that's been eating at me all afternoon and I dont fly again until Tuesday so here I am...

So will the CDI needle be accurate for a Localizer approach regardless of the selected OBS as I believe or are my instructors correct in stating that the OBS must be set to the runway heading for the CDI to offer the correct course information?

NOTE: This is not a best practice question but one of base/actual functionality.
 
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Functionality you're correct. It's just good habit they're trying to instill in you (I hope).
 
Thanks Mkosmo. That's what I thought. I did suggest it was a best practice/good habit to have when talking with both instructors about it but the authority with which they said it had to be set to the heading just left me going "huh?"

Maybe I wasnt clear enough in my suggestion either that or when I go flying on Tuesday and "test" my "theory" with the instructor, they'll learn something...
 
Yep, you are right. Any instructor who gets wrapped around the axle over this deserves to be dumped.

Note on the other hand that the COURSE ARROW on an HSI (which does what an OBS does on a regular VOR head) is very much important when tuned to a LOC. On an HSI turning the arrow rotates the CDI on the heading indicator face. While turning it has no affect on the needle displacement, the needle will be displayed in the wrong orientation if you don't set the arrow to the inbound course.
 
You are correct as to function, and the instructors are correct as to practice. I suspect that Ron has tagged the most compelling reason, as well; flying a localizer with an HSI course needle set improperly would be confusing, at best.
 
Correct. On an ILS, the OBS doesn't need to be set to the final approach course, however I always set it to give me the best situational awareness and can get confusing if not set correctly.
 
flyingron said:
While turning it has no affect on the needle displacement, the needle will be displayed in the wrong orientation if you don't set the arrow to the inbound course.
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Note: This means the "localizer's inbound course" not the pilot's, say for instance on a back course. There you'd set it opposite of the way you want to be heading on final.

dtuuri
 
dtuuri said:
Note: This means the "localizer's inbound course" not the pilot's, say for instance on a back course. There you'd set it opposite of the way you want to be heading on final.

dtuuri
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Correct. Nice thing about setting the course arrow correctly (localizer inbound course) is there's no "reverse" sensing when either flying the back course or outbound on the front course.
 
flyingron said:
Correct. Nice thing about setting the course arrow correctly (localizer inbound course) is there's no "reverse" sensing when either flying the back course or outbound on the front course.
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Good point... I've flown the back course with the HSI set to the "correct" heading and just flew it with reverse sensing; didnt really think about flipping it 180 and having it sense correctly...

I like to set the OBS; like I said, I recognize its a good practice to have but I dont mind when its not perfect, especially during the initial turn to final. Plus my runway numbers not the actual heading. So in the case of my local airport, I like to set OBS to 240 for heading 245 while my Instructor wants 245 for runway 240.

I also dont like to change it when trying to do single VOR operations and establishing on the localizer since having to change back and forth between VOR tracked radial to LOC tracked approach course requires a fair bit of attention.

I had an HSI in an aircraft I flew recently that had a bit of friction between the indicator and the compass cards and changes like that would see the indicator "catch" the compass card introducing error; doing it repeatedly while flying with a single HSI would compound the error significantly
 
apr911, welcome to the world of IR, you will enjoy your training.
Talk to your instructors. Discuss with them. The outcome should be an understanding that while setting the OBS/HSI to the rwy heading is a good habit, it is not required for the LOC signal to display properly. If they do not agree, try to explain it to them. If they refuse, find a smarter instructor.
(I have been lucky in all my training, I always had a smart instructor)

Again, enjoy your training, it is a blast!
 
It is a good habit to turn the obs to the correct heading. Makes different approaches work more identical. A vor approach could be a bad time if you forget to turn it to the right heading and certain vor approaches act very similar to a LOC approach
 
apr911 said:
Thanks Mkosmo. That's what I thought. I did suggest it was a best practice/good habit to have when talking with both instructors about it but the authority with which they said it had to be set to the heading just left me going "huh?"
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When I tell as student to the inbound course (not heading) because that's the way I want him to do it, I say it with authority also. :D

But yeah, if you don't it know already, instructors can be somewhat less than the font of knowledge we try to make them into. Many repeat what they were taught without ever "fact checking" the source. You know, a lot like real life. :wink2:
 
I tell my students to swing the CDI to the inbound course no matter the type of approach. This is to keep them use to doing it and gives them situational awareness.

If it's 146* I don't care about that 1* unless it's a digital CDI.
 
No need to fire anybody.

Next time you are on an ils or loc approach with one of the instructors, and comfortably established inbound, reach up and twist the obs to 90° off your heading.

See what happens, see if they have a reaction! :D
 
Let'sgoflying! said:
No need to fire anybody.

Next time you are on an ils or loc approach with one of the instructors, and comfortably established inbound, reach up and twist the obs to 90° off your heading.

See what happens, see if they have a reaction! :D
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Maybe even better since it might even be considered a reasinable procedure? At least without GPS.

The flip-flop on the nav is tuned to the VOR needed for the missed. Once comfortably established inbound on the localizer, spin the OBS to the radial/course needed for the missed, so the only thing you need to do going missed is hit the flip-flop button.
 
flyingron said:
.....
Note on the other hand that the COURSE ARROW on an HSI (which does what an OBS does on a regular VOR head) is very much important when tuned to a LOC. On an HSI turning the arrow rotates the CDI on the heading indicator face. While turning it has no affect on the needle displacement, the needle will be displayed in the wrong orientation if you don't set the arrow to the inbound course.
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That. (Minus the dumping the CFI part).

Your CFII is correct, you need to set your OBS to the approach course, not because the needle won't read the same, but because you're making your brain do much more work, working on a screwed up representation of your approach when compared to setting the OBS to the correct heading.

I know with a standard nav head this doesn't matter as much, but you have some caddy womous OBS setting with a HSI while you're shooting a approach to minimums in IMC, at night, while you're tired, it could really screw you up.

You practice like you want to preform and you'll preform like you practiced.


Listen to your CFI, and set the OBS to your approach course.
 
IRL in recent instrument training, I found myself glancing at the OBS while on a localizer as a regular part of my scan. It's a substitute for a heading bug, except it reads course.

It helps A LOT staying centered on that localizer.
 
James331 said:
.....
I know with a standard nav head this doesn't matter as much, but you have some caddy womous OBS setting with a HSI while you're shooting a approach to minimums in IMC, at night, while you're tired, it could really screw you up.

You practice like you want to preform and you'll preform like you practiced...
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^^^This!:yes:
 
James331 said:
That. (Minus the dumping the CFI part).

Your CFII is correct, you need to set your OBS to the approach course, not because the needle won't read the same, but because you're making your brain do much more work, working on a screwed up representation of your approach when compared to setting the OBS to the correct heading.

I know with a standard nav head this doesn't matter as much, but you have some caddy womous OBS setting with a HSI while you're shooting a approach to minimums in IMC, at night, while you're tired, it could really screw you up.

You practice like you want to preform and you'll preform like you practiced.

Listen to your CFI, and set the OBS to your approach course.
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James,

I agree fully and I DO understand the value in turning the OBS to match the heading for the localizer, especially when shooting the LOC under IFR conditions.

My question was based more on the actual functionality and of course the plethora of routes that use an airport's localizer as an intersection. The "argument" with my instructors was that the CDI needle would not function correctly if the OBS is not set to the heading indicated on the approach chart.

For an approach, it would make sense to set the OBS to match your heading but for an intersection, I like to set the HSI "off" the indicated heading for the LOC and more in tune with my directional heading.

As you indicated, it looks funky with the HSI being turned but doing so gives me a visual representation of where I am in relation to the interesection... That is if my heading is 360 my localizer is 090 and I tune 360, the HSI needle will be "low" when Im south of the intersection and "high" when Im north of the intersection but as my instructor was explaining it, this would not actually work despite my experience to the contrary (though I usually had a GPS backing me up and was thus less reliant on the accuracy of the VOR/LOC so I may not have noticed a discrepancy)...

I like to do similarly when trying to establish on the localizer as I've found I respond better and more on time to the turn to final using my heading for OBS on an HSI than I do trying to make the turn to final with the HSI set to the runway heading. Once I establish, I turn the needle correctly.

For some reason I process and react to the needle being low/high better & quicker than left/right in that initial turn and I find myself chasing the needle down the approach after overshooting the turn when my instructor "corrects" my OBS before establishing. Using the HSI in a horizontal orientation helps me make that turn smoothly in a more like a tiny Arc than a hard turn.

None of the above works correctly however if my instructor is functionally correct regarding the Localizer and the OBS having to match and not just as a best practice.

Of course, HSI's aside, a regular CDI indicator makes no difference since they dont change orientation like the HSI.

Also as someone else noted, until Im flying with an all digital glass cockpit, even with the HSI screwy orientation, setting the HSI to a gross heading that is reasonable to actual heading is close enough for the LOC approach to function and not require much brain power to do... That if Im flying that 090 LOC and I set OBS to 100, the HSI might be off a bit but not so much as to be diifcult to interpret and understand and more importantly, not so much that if I center the needle and follow, I will still be landing at my intended airport and not in a field on a house that's the same distance from my current location but 10 degrees further south.

Not to mention as I mentioned previously, it can be quite painful doing single HSI/VOR indicator operations and trying to turn the OBS card back and forth between LOC intercepts and your current heading and can introduce error other error on the instrument quickly
 
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In that case you're processing information wrong.

You need to set the OBS correctly and interpret it as such, learning bad habits will cause you issues later, or worse.

Yeah the mechanics will allow what you are talking about to "work" problem is what you're talking about doesn't really work in the real world.

There are some questions that I just shut down and do go down the path, this is one of them, learn it correctly (as your CFI was saying) and become a good IMC pilot.
 
Glad this is for James because you have me all confused.

apr911 said:
James,

... That is if my heading is 360 my localizer is 090 and I tune 360, the HSI needle will be "low" when Im south of the intersection and "high" when Im north of the intersection but as my instructor was explaining it, this would not actually work despite my experience to the contrary...
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You sure about that?

dtuuri
 
apr911 said:
As you indicated, it looks funky with the HSI being turned but doing so gives me a visual representation of where I am in relation to the interesection... That is if my heading is 360 my localizer is 090 and I tune 360, the HSI needle will be "low" when Im south of the intersection and "high" when Im north of the intersection but as my instructor was explaining it, this would not actually work despite my experience to the contrary (though I usually had a GPS backing me up and was thus less reliant on the accuracy of the VOR/LOC so I may not have noticed a discrepancy)...
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You've obviously not played with an HSI (or a simulation of it). If you the heading is 360 and the Course Arrow is 360, the needle will go left and right not up and down. (Further, cdi indications are really better described as RIGHT and LEFT than any other positional words even if presented horizontally....it's right and left wrt the arrow itself).

I like to do similarly when trying to establish on the localizer as I've found I respond better and more on time to the turn to final using my heading for OBS on an HSI than I do trying to make the turn to final with the HSI set to the runway heading. Once I establish, I turn the needle correctly.
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No, you need to find an instructor who can explain things to you correctly.
You need to set the course arrow to the LOC inbound course (which is NOT necessarily the runway heading) as soon as you tune it on the radio. It makes absolutely no sense for ANY REASON to do otherwise. If you want a reminder of what heading you want to fly for an intercept, that's what the HEADING BUG is for. That's the other knob (typically orange as opposed to yellow for the course) is for. You can spin the BUG all over the place without making any visual effect on the deviation indicator.
 
Set it to the inbound course so you do it the same way every time. KISS. Also, if you or others are interested...if you are flying an auto land authorized/equipped aircraft and for some reason you need to manually tune the localizer course in the FMS for an ILS approach with an auto land, if it isn't set within a couple of degrees of the correct inbound the aircraft will not have roll out guidance after touchdown and your landing capability will be downgraded.


Sent from my iPhone using Tapatalk
 
Another important reason to always set your OBS to the inbound course is to provide the course datum to the autopilot. It can't guess the no wind course.

An ILS localizer doesn't use the OBS setting as input that affects the CDI. For that matter, neither does a GPS course based on a flying a leg. A main value of an HSI is to aid in the visualization and therefore pilot situational awareness. Setting the OBS on the HSI accomplishes this, regardless if it affects the CDI left/right position, so if you were my student, I would insist on properly aligning the course on the HSI. On a G1000 system, the auto slew feature will do this for you.
 
This question has taken on a life of its own! Probably because I did a bad job explaining why I was asking and then compounded that with horribly wrong examples with bad terminology and worse explanations involving an HSI...

Let me see if I can rephrase and summarize the answer:

1) Question: Does OBS setting for a LOC really matter on a fixed orientation CDI?

Why Ask? 2 reasons.

Number 1, resource/task management and reduction of pilot load

Maybe you only have 1 CDI or you're using both CDI's for distinct purposes (tracking in to next station on CDI1 and out from last station on CDI2 or maybe CDI1 is GPS and you are cross checking the indications with CDI2 on VOR or any other distinct purpose you can conceivably argue) and/or you already have the NAV already programmed for the next leg. So what do you do when you receive an unexpected instruction to fly to an intersection identified by a localizer?

The frequent changes needed to the NAV system needed to maintain previous settings while tracking the intersection adds to the level of task saturation, adds an additional focal point inside the cockpit upon which to fixate while your situational awareness decreases and flight becomes increasingly erratic and dangerous, adds additional potential points of failure (maybe the pilot forgets to reset the OBS for the next leg) in the instruments through frequent retooling the configuration and so on.

If the CDI does not "care" what it's tuned to when using a localizer, you dont have to worry so much about directional OBS on the CDI and only have to be concerned about tuning to the station, identifying the station correctly and confirming when you do pass through that localizer's signal and thus the intersection all without mucking about with the OBS setting thereby allowing you to keep most of the NAV settings as configured and a radio channel swap push button away from returning to or continuing on to the next navigational point.

Number 2, flying a localizer back course. It was not clear how this would even functionally work if the needle only deflected correctly when the OBS was set correctly because this would mean setting the OBS to something other than the localizer's or your course (you are setting the reciprocal).

Additionally, if the CDI did have an impact on the localizer approach course there would never be any reason to reverse sense on the needle because you could just set the OBS to the reciprocal direction just like when going to/from a VOR.

Answer: It is a best practice to set the OBS to the direction indicated on the approach plate, especially since this is required for VOR navigation but the signal of the localizer will cause the same needle deflection regardless of OBS setting.


2) Question: Does OBS setting for a LOC really matter on an HSI where the needle orientation can rotate?

Why Ask? Technically, I didnt. I was asking about a fixed orientation CDI and then confused things by making reference to flights in which I used a CDI. The planes Im flying now for my instrument rating dont have an HSI so the HSI discussion is somewhat irrelevant to the topic of conversation I had with my instrutor. That being said the HSI conversation was fairly good and there are some considerations for the HSI which can be detrimental or beneficial to your flight if you know they exist so I've decided to include the question in my summary.

Answer: Like the CDI, the localizer will cause the same needle deflection in an HSI regardless of OBS setting so setting it is not strictly necessary to set the OBS direction, particularly when finding an intersection however when actually flying a localizer approach, the fact the HSI needle orientation is not fixed can cause issues correctly interpreting the output. This error however can also be leveraged to your advantage.

For example:
if you are flying the localizer approach and the OBS is set to +/- 45 to +/- 90 from the localizer course, the orientation can be difficult to process.
if you are flying the localizer approach and the OBS is set to +/- 90 to +/-135 from the localizer course, the orientation can be difficult to process and it is reverse sending. At OBS settings greater between +/-135 to +/-180, the orientation might not cause issues but you are now reverse sensing.

This behavior can be used to your advantage when shooting a Localizer Back-Course approach because you can flip the needle orientation 180 degrees and fly the back-course without reverse sensing.


Additionally, an HSI with the OBS set correctly will give the pilot an indication of their crab angle relative to the runway along the localizer course. Not that this cant info cant be gathered with a fixed oriented CDI with a heading indicator and heading bug, the HSI provides the reference at a glance.

Other than having to be concerned with the "pole" of the needle and correctly orienting it, the HSI has 1 additional caveat when compared to CDI's: The system is not completely frictionless and one of the issues with combinging 2 semi-related but independent instruments is the unexpected crossover between them. I did in fact experience an HSI that had a significant friction point between the compass card and the OBS and making changes to the OBS would cause the compass card to stop turning at certain points which induced minor heading errors. These errors were quickly compounded to a signficant error in the indictor/compass card due to multiple changes in short succession. While I caught during my next cross check of compass heading to HSI heading, it was well outside the acceptable precession rate of 3 degrees per 15 minutes and would have been inadequate for instruments. During the next tuning, I saw the catch occur and was able to 1) accurately sqawk the HSI (it had been noted before but on tests in straight flight found to be fine), 2) once on the ground, was able to find the points where the compass card and needle would catch and 3) because I now knew those points, I knew any time the needle orientation passed through that heading, I would need to correct the error and plan my turn accordingly (either correcting by continuing the turn longer than the heading indicator suggested and fixing the heading after the turn, or changing the OBS and fixing the heading ahead of the turn to avoid the "catch" while in the turn).



The last caveat in both cases is when using the localizer for an approach with an auto-pilot system. As SinglePilot and JohnCollins point out, these systems often need everything lined up as their "input" datum to adjust and correct for winds. I dont presently fly many planes with autopilot and even those I do, I dont regularly engage it nor do I particularly see myself using it in a final approach but as I step up into larger, faster aircraft on routes with more time, distance and/or complexity, I can certainly see how that will change.
 
Also, having reworked my earlier examples on a SIM, as I should have done in the first place, I can see trying to recall what I was doing almost intuitively as part of my normal "flow" nearly 2 months ago when I last flew an HSI equipped airplane was a bad idea. Not only was my visual picture wrong but I then did a bad job explaining it, using worse terminology which gave a really bad impression that I had no idea what was going on with an HSI and royally confused things further.

So here's the problems reworked:

Intersections:

LOC: 220
HDG: 360
OBS: 270

By always putting the OBS 90 degrees left of present course, I get a sight picture on the HSI that shows:
Before the intersection, the needle is way out in front of the plane
At the intersection, the needle centers through the wings of plane on the HSI
Beyond the intersection, the needle is way out behind the plane.

Or if Im using only a single HSI or have both HSI's doing "something," making no change to the heading allows me to find the intersection and then resume the previous task with minimal change (just swapping the radio channel).

Setting OBS to 320 does give a slight indication of that alignment but it also is reverse sensing since you are flying away from it.


Intercept:
After putting it in a SIM, I realized this is probably less helpful in IFR because:

1) The turn on course where I've found this helpful would probably utilize a procedure turn for entry in IFR.

2) In most cases, even if you started your turn as soon as the needle moved, you'd still blow right past the course centerline before you've come around at standard rate.

3) even the below illustration is toast in anything that goes too much faster than 100-130.

That being said, the only IFR approach I can think of that would illustrate what I was trying to describe and is actually doable completely using the HSI with LOC signal and no other references is an approach that uses a DME ARC for entry as the ARC would puts you out on a heading perpendicular to the intermediate fix requiring a 90 degree turn. Im sure someone will come and tell me no such approach exists and that's fine, at this point Im just trying to illustrate what I was doing because my last explanation didnt explain it correctly and further gave off the very bad impression that I have no idea what Im doing with an HSI (which may still be proven true but Ive used this on multiple flights at night over dark mountainous terrain so Im either very very lucky or at least have some understanding).

At a distance of 15 NM and 100kts, a standard rate turn initiated when the needle moves to 9 degrees of deflection will put you on course and, if done correctly, on center for final but its still a forced example.

Because the IFR example is still far from ideal, Im going to skip it entirely but here's an example of what I do when VFR. Under visual conditions with all that it entails (not needing to intercept the LOC and Glideslope at IF which means the ability to initiate the turn earlier and greater than at standard rate), it has worked well for me. Here's a VFR example:

1. Coming out on heading 335 for LOC 245
HDG 335
OBS 290
Bug 245

By skewing the halfway between current heading and final heading, I get a sight picture on the instrument that shows the tip of the needle/arrow in front of the plane and to the left.

2. As the needle comes alive, initiate standard rate turn until OBS and HDG match and roll-out. Maintain heading and, because HDG & OBS dont match final (as set by bug), reset obs.
HDG 290
OBS 275
BUG 245

3. As the needle moves to 8-10 degrees deflection, initiate 2nd standard rate turn until HDG & OBS match and roll-out. Maintain heading and, because HDG & OBS dont match final (as set by bug), reset OBS
HDG 275
OBS 260
BUG 245

4. As needle moves to 5-7 degrees of deflection, initiate 3rd standard rate turn until HDG & OBS match and roll-out. Maintain heading and, because HDG & OBS dont match final (as set by bug), reset OBS
HDG 260
OBS 245
BUG 245

5. As needle moves to 2-4 degrees of deflection, initiate final turn at variable rate until HDG, OBS, BUG match and needle comes to center.
HDG 245
OBS 245
BUG 245

Everything is in agreement and alignment and now I just need to offset as appropriate for winds to keep it that way.
 
In any case, my instructor and I discussed it further and after a pause we agreed on the operation but we also agreed why it was a good idea to set the OBS regardless...

Though we haven't flown any airway's with a LOC intersection without GPS where the real value (at least in my mind) of not having to set the OBS to the localizer course heading is...
 
Again, it's not bad practice as long as everybody understand what is going on.
 
apr911 said:
In any case, my instructor and I discussed it further and after a pause we agreed on the operation but we also agreed why it was a good idea to set the OBS regardless...

Though we haven't flown any airway's with a LOC intersection without GPS where the real value (at least in my mind) of not having to set the OBS to the localizer course heading is...
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:dunno: Why do you think not setting the LOC as a reference to the course heading would be a "real value" for an intersection?

I guess it just shows how different people are. There's a current thread where the question was asked about bugs and other ways to recall the altitude and heading one was given. Now here's a thread in which you are taking the view that setting a reference that takes less than a second doesn't have much value to you.

Flight, and instrument flight in particular is about SOPs and habit patterns. You may be one of the exceptions but I'd bet most CFIIs have seen pilots who don't like to set the OBS for a LOC do two things somewhere along the way with very little workload increase, probably both: (1) for a VOR, forget to set the OBS; (2) for a LOC, turn to intercept the the heading that is on top of the OBS rather than the LOC course.
 
midlifeflyer said:
:dunno: Why do you think not setting the LOC as a reference to the course heading would be a "real value" for an intersection?

I guess it just shows how different people are. There's a current thread where the question was asked about bugs and other ways to recall the altitude and heading one was given. Now here's a thread in which you are taking the view that setting a reference that takes less than a second doesn't have much value to you.
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Go back 2 posts and start at the beginning.

I dislike mucking about with my CDI's once they're set unless Im changing my course; this is particularly true when I may only have a single CDI.

Go fly an airwary in a plane with a single CDI and then come back and tell me there is value in changing the OBS from the airway you are on and tracking to the localizer heading you are intercepting solely for an intersection/waypoint reference.

Where is that value in that situation? You are doing a lot of OBS turning, possibly setting yourself up to incorrectly reconfigure your radial track or next turn just so you can get the OBS to match the course of the LOC when the LOC will display the same information regardless.
 
Yet another example of instructors barking orders without explaining the "why" behind what they want you to do..one of my biggest pet peeves when I worked in the training environment. The reason I always taught my IR students to twist the OBS to the inbound on a LOC is to enhance situational awareness of where you need to be headed and help you visualize any wind correction you're having to put in by comparing the DG and OBS. Plus it's a good habit to get into as correctly setting the OBS will become habit regardless of what type of approach you're doing (I can think of a few accidents involving approaches into rough terrain that were caused by improper setting of courses)..plus if you ever fly anything with an HSI, you'll need to properly set the OBS to make the approach doable.
 
apr911 said:
Go back 2 posts and start at the beginning.

I dislike mucking about with my CDI's once they're set unless Im changing my course; this is particularly true when I may only have a single CDI.

Go fly an airwary in a plane with a single CDI and then come back and tell me there is value in changing the OBS from the airway you are on and tracking to the localizer heading you are intercepting solely for an intersection/waypoint reference.
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Sorry, I didn't realize you were under a disability. ;)

But, OK, I will tell you, for me at least, there is value in that. And I don't even have to go do it and come back. My instrument training 20+ years ago was with a single VOR and an ADF, no DME or GPS, so, yeah, I do have a small idea what it is like. :yes:

I periodically tuned in a crossing VOR, hit the flip flop, and took an extra whole second or two to spin the OBS to get a crossing VOR radial. Heck, it was SOP on VFR cross country flights when I was a student and private pilot limited to VFR flight.

Value to me under IFR? Situational awareness not available otherwise and a consistent SOP for both VOR and LOC not likely to be forgotten when needed in high workload situations. If those aren't valuable to you, as I said, just shows how folks are different.

No, I would not want to do that while on the FAC of an IAP to try to get step-downs. Heck, I wouldn't want to do that with 2 VORs! I'd rather accept the higher minimums not using the step-downs.

But while in the relatively low workload en route cruise environment while tracking an airway? Plenty of time.
So I've finally started my instrument training
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Sounds like you may be having difficulty with managing workload. That's to be expected in the early phases of instrument training. But it should get better as your training progresses.
 
midlifeflyer said:
:dunno: Why do you think not setting the LOC as a reference to the course heading would be a "real value" for an intersection?
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Maybe I'm misunderstanding what you're saying, but this sounds like a really bad idea for the occasional case of crossing a localizer.

My SOP is to set the OBS for the localizer course, not the aircraft course. This makes it exactly like an extra-sensitive VOR. Setting it to current course would be massively confusing, as it would behave differently if the localizer were on the left side or the right side.

If I'm tracking the localizer, I'll consider setting it to heading (not course) in those aircraft that don't have a GPS, and fine tune it as the wind changes. Sort of like a heading bug.

On an HSI or glass panel, I generally don't have much choice over just showing the bearing to a crossing localizer, as the CDI will be set to the current course and primary navaid regardless.
 
MAKG1 said:
Maybe I'm misunderstanding what you're saying, but this sounds like a really bad idea for the occasional case of crossing a localizer.

My SOP is to set the OBS for the localizer course
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Unless I am the one badly understanding, the original scenario was as simple tracking of a LOC - whether one should spin the OBS to the on-course number. And, my answer agrees with yours and I think everyone who responded - the better practice is to set the OBS for the localizer course.

But the OP morphed the discussion into a scenario in which the pilot is following an airway (VORs) and identifying an en route intersection or crossing localizer with enroute functions (not that many but they exist) in the same way as one would use a crossing VOR radial for situational awareness - should the OBS be spun if the crossing navaid is a LOC rather than a VOR.
Though we haven't flown any airway's with a LOC intersection without GPS where the real value (at least in my mind) of not having to set the OBS to the localizer course heading is...
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My answer is the same - the better practice is to spin the OBS to the localizer course.

Edit: Thanks for the wise input guys
 
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Palmpilot said:
Don't you mean spin the OBS?
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Yeah, he need to get those mounting screws on the VOR head tightened.

Frankly, I don't fly a plane with one VOR head and I hope never to have to. The last plane I flew with one VOR wasn't one I wanted to take into real IFR anyhow (Cessna 170 with venturi-gyros).
 
Palmpilot said:
Don't you mean spin the OBS?
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No. I like thinking of the CDI as a miniature propeller
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