Questions on intercepting a course(GPS)/a glide slope (VLOC) using HSI

[clairvoyant]

Folks, I need your IFR professional pilots' expert opinions here.

For the longest time, I usually use 30-40 degree angle to intercept a course then as the CDI is getting tighter (like between the closest dot and the aircraft symbol), I turn (1 rate/20 degree bank) to the selected course indicator.
Then, I met this flight instructor for my IFR flight test who told me to turn gradually once the CDI started to move inward, turned the plane so as to keep the lubber line on the tip of the CDI.

For whatever reason, I ended up chasing needles, chasing air speed, and over correcting using her method.
Did I miss something here?

During the ILS approach, that CDI is extremely sensitive once tuned to VLOC that I prefer not to chase anything and second guessing.
The difference between lining up on the runway for landing and lining up at someone's residence on MDA/DA/DH is not the risk worth taking here.
What's the best method/fail proof on intercepting HSI?
Ideally, I'd rather fly an aircraft with an autopilot during the IFR test/checkride but just in case......

Thank You for your insights in advance, folks.

[172_Captain]

You have your way, your instructor has her way. As long as your way is working, then you’re good to go. There’s many different ways to achieve the same result. One common thing in instructing seems to be viewing things as black and white. I say do what works best for you.

[clairvoyant]

Thank you, captain....
Will my way lead to "not recommended" for a flight test?
I wonder what the examiner methods or whoever has successfully passed the IFR flight test. I am trying to play safe here.

[AOW]

It is important to recognize what information the CDI is based on. For traditional VORs and ILSs, deviations are based on angles, so the closer you are to the station, the faster the needle will move. GPS derived CDI needles, on the other hand, are based on distance off track, so as long as the scale remains constant, the needle will move at the same rate regardless of how close or far you are from the fix.

My best suggestion is to learn how to incorporate raw data from your GPS into your scan. The two most important things for you are TRK and BRG (or whatever “present track” and “bearing to fix” are called on your display). Garmin GPSs stupidly (IMHO) prioritize DTK (desired track) over BRG; DTK is what your OBS should be set to, but after that you don’t have to do anything with it until you turn (or you have flown far enough east or west that the great circle route has caused a significant enough change in DTK).

To understand how to use BRG and TRK, start with the basics. BRG is the bearing from your present location to the next fix. So if you make your TRK equal to your BRG, you are on a direct track to the fix. It doesn’t matter at that point what your DTK is, as long as you keep your TRK equal to the BRG, you will pass directly over the fix.

Since we care about more than just passing over fixes, such as following the desired track to that fix, use the BRG and TRK information to help you intercept the DTK. If for example your DTK is 270, but your BRG is 250, you should expect the CDI needle to be some distance off to the left. You correct by turning 30 degrees to the left. This sounds like a reasonable plan...

But let’s say now your BRG is still 250, and your TRK is 251. That means that your heading change was not enough to even have you go directly to the fix, so if you maintain this track, you won’t intercept until past the fix. You need to turn even further in order to intercept the track before reaching the fix.

By using this method, as the BRG gets closer to the DTK, you can shallow out the intercept angle, to ease onto the correct course, and when the CDI needle centres, you should have BRG, TRK, and DTK all equal. Now keep adjusting your heading as required to keep all 3 equal, and you shouldn’t see the CDI needle budge off the centre. I always use the heading bug to mark the heading that is giving me the desired TRK, and that gives you an easy reference to aid your scan.

This method follows through to flying an ILS, or tracking a VOR even if it is not loaded in the GPS. As long as your GPS continues to display TRK, use it! Keep scanning the GPS for your TRK, and when the needle is centred, make sure the TRK matches the ILS course or selected radial. If you need to make corrections, especially on the ILS, make small ones, pay attention to the effects on your track, and always come back to the appropriate TRK. Bug the heading that works, and make your life easier!

I hope this all makes sense, and helps rather than confuses.

Good luck.

[clairvoyant]

Thank you so much for the insightful information, AOW.
I am using GNS430W for this training.
On my training, I did ILS and LPV. Somewhat LPV behaved as sensitive as that of ILS. Is that the case?
....and yes, don't forget to press the CDI button to switch from GPS to VLOC as I get closer to catch the glide slope.

....just to play safe here....
If I were to use an autopilot during an IFR flight test, [hypothetical emergencies and all other circumstances aside] at what point do I arm/disarm it during the IFR flight tests for climbs, approaches, en-route, etc.?

I heard horror stories how examiners throw a knuckle ball such as instructing students to hold at waypoints [unpublished holds]. I know how to enter the holds and such but I want to be able to push the OBS button at the right time, time the entry, and set up the HSI so I know [the references] when/where to turn.

....or perhaps this is the right time to change an instructor?

[Outlaw58]

Thank you, captain....
Will my way lead to "not recommended" for a flight test?
I wonder what the examiner methods or whoever has successfully passed the IFR flight test. I am trying to play safe here.

The examiner will look at your performance. Do you maintain altitude, speed and heading/track within tolerances. It isn't the how he is interested in, just the end result and you're overall S/A and airmanship which will determine which way he will lean in the odd cases of grey area. TC test standards are published, your instructor should have briefed you on them already. You can look them up!

58

[photofly]

It is important to recognize what information the CDI is based on. For traditional VORs and ILSs, deviations are based on angles, so the closer you are to the station, the faster the needle will move. GPS derived CDI needles, on the other hand, are based on distance off track, so as long as the scale remains constant, the needle will move at the same rate regardless of how close or far you are from the fix.

Just for information, if you have a GPS that will display an LP approach (are there any in Canada? I'm not sure) you'll find that unlike LNAV and LPV the course guidance is based on angular deviation and not cross-track distance.