Selecting radials for radial interception

Question

I’m a beginner in intrument flying so sorry for my ignorance. Few months ago I was doing BIR training and with my CFI we were intercepting radials, we were doing that on HSI (Garmin G500).

He told me that If I want to intercept radial inbound I should set the tail of the needle to the desired inbound radial and if I want to intercept radial outbound I should set the head of the needle to the the desired outbound radial.

My question - is this way of setting desired radials correct? Because I read somewhere that we always should set the head of the needle to the course that we mean to fly, no matter if it is outbound or inbound - to avoid reverse sensing.

So if I want to intercept and fly radial outbound 180 I should set head of the needle of my HSI on 180 and if I want to intercept and fly radial 240 inbound I should set the head of the needle of my HSI on 240. Now I'm confused, please help me out.

Answer 1

Your instructor is correct - using his method, means you do not have to do any reciprocal course/heading/plus/minus 180 calculations - instead you must remember "Radial 050 outbound" set the head (arrow/course) on 050. "Radial 160 inbound" set the tail on 160 which means the head/arrow/course will be on 340. It's evident that you have to simply use the Radial as spoken by ATC and acknowledged by you without further calculation.

@Konrad, going back to your last paragraph

"So if I want to intercept and fly radial outbound 180 I should set head of the needle of my HSI on 180 . . . ."

So far, so good! but

". . . and if I want to intercept and fly radial 240 inbound I should set the head of the needle of my HSI on 240. Now I'm confused, please help me out."

but your instructor told you to set the tail of the needle to 240. Had you done this, the head of the needle of your HSI would be on 060 which is the course you must fly.

So your thought process should be like this:

"OUTBOUND" -> SET HEAD TO CLRD RADIAL - INTERCEPT AND MAINTAIN.

"INBOUND" -> SET TAIL TO CLRD RADIAL -> GLANCE AT HEAD TO READ OFF CRS + CONFIRM IT IS CONSISTENT (~RECIPROCAL) WITH THE HEADING TO BE FLOWN -> INTERCEPT AND MAINTAIN.

In either case, after these initial actions make a cross-check using pencil and paper or looking at a chart and the pilot in the other seat (if any) to maintain situational awareness (SA).

Some food for thought about nomenclature:

Better to say "cleared radial" rather than "desired radial".

When it's a HSI style display call it head/tail of "course selector" rather than "needle", (as compared to an RMI style display which has needles)

Answer 2

This is a terminology problem - and I think you're actually both right but you need to learn the terminology. Radials always radiate out from the VOR.

You should absolutely always set the needle to the heading you intend to fly in order to avoid reverse sensing.

However, if you're intending to "fly inbound on the 240 radial" then you're actually on the reciprocal heading of 060 - which is what should be set on your OBS. The flag should indicate "TO".

If you're flying outbound on 180 then you should set 180 on the OBS and the flag should indicate "FROM".

Answer 3

Well, all of you (and, the instructor) are correct for using your own technique on the aircraft in which you are familiar. The technique can vary depending on your equipment. So let’s clear up a few things.

1. You can not get reverse sensing with a properly working HSI (which the G500 should have). This is because the HSI should always orient the displayed heading (or, top of the instrument / lubber line reading) with the actual aircraft’s heading. You will only get reverse sensing when the indicated course or radial at the lubber line and the actual heading are in opposite half’s (top and bottom) of the instrument. This happens in a VOR OBS with a movable card since the desired radial is always at the lubber line.
2. The technique described by the OP makes sense. It completely ignores the “To/From” Indicator on the VOR which confuses some beginners. It sets the HSI up to indicate only To when you are inbound and From when you are outbound regardless of which side of the VOR you are on. It also has the added benefit of always aligning your Radial arrow with your desired course and heading. Similar to how it will be when you are lining up for your final course on an ILS or localizer. This will also avoid reverse sensing in a regular VOR OBS indicator. When you learn to properly use the HSI, you might stop using this method. Although it may behoove you to stop using it now since there will be VOR questions on the written Knowledge Test which will require you to have intimate knowledge of the VOR OBS and HSI.
3. Another method to use for the long run is to always place your desired radial to intercept in the course window to move the point of your needle to that degree. Then note where the To/From indicator is pointing. It will always point in the direction of the VOR. Upon intercepting the radial, turn towards and fly in the direction of the To/From indicator if you want to go inbound to the VOR. This method has the added benefit of giving you situational and spacial awareness of where you are in relation to the NavAid since the radial needle will always be pointing down the radial like an extended center line. And, the To/From indicator dispels ambiguity.

Answer 4

He told me that If I want to intercept radial inbound I should set the tail of the needle to the desired inbound radial and if I want to intercept radial outbound I should set the head of the needle to the the desired outbound radial.

My question - is this way of setting desired radials correct? Because I read somewhere that we always should set the head of the needle to the course that we mean to fly, no matter if it is outbound or inbound to avoid reverse sensing.

Both of these statements are true. By setting the tail of the needle to a desired inbound radial you're flying in the direction of the head of the needle.

So if I want to intercept and fly radial outbound 180 I should set head of the needle of my HSI on 180

Correct

and if I want to intercept and fly radial 240 inbound I should set the head of the needle of my HSI on 240. Now I'm confused, please help me out.

This is wrong. If you set the HSI needle (aka course bar) on 240 you are in fact planning to fly the 240 radial outbound, in the direction of the arrow. If you want to fly it inbound then put the tail on 240 so that you're flying the reciprocal direction (060) which is pointing the arrow toward the beacon.