VOR Radials

[n65z]

To preface, I rely on my GPS to get me from point A to point B too much.

I want to learn to fly like the big kids, so I am practicing my VOR radial tracking (offline) until I am confidant enough to do it with PE ATC.

I am almost there, except.....

Going from KSNA to KCRQ. Upon leaving KSNA, I tune to the SLI VOR and set my course to 120. This supposedly...and looks like it does, put me on the V23.
Everything is peachy at this point. I am now tracking SLI120R on the V23 with no problems.

2.5 Questions. 1) Looking at my GPS for reference only, I notice that I am off track and V23 is to my right. How far off-track am I "allowed" before getting "yelled" at by ATC? Why am I off-track?
2) At which point do I switch to OCN and track that inbound?

[wmburns]

How far off-track am I "allowed" before getting "yelled" at by ATC? Why am I off-track?

The distance between SLI and OCN is listed as 40 nm. Therefore the Victor airway is 8 nm wide (4 per side). So they are actually fairly wide.

<source Widipedia>
When VORs are less than 102 nautical miles (NM) (189 km) from each other, the airway extends 4 NM (7.4 km) on either side of the centerline (8 NM (14.8 km) total width).

When VORs are more than 102 NM from each other, the width of the airway in the middle increases to account for the increased margin of error in the VOR signal. The width of the airway beyond 51 NM from a navaid is 4.5 degrees on either side of the centerline (at 51 NM from a navaid, 4.5 degrees from the centerline of a radial is equivalent to 4 NM). The maximum width of the airway is at a designated changeover point between the two navaids, usually half way.

http://en.wikipedia.org/wiki/Victor_airways

Why am I off-track?

The VOR's and GPS disagree because the Earth's magnetic poles drift over time.
http://www.askacfi.com/3857/true-course ... adials.htm

2) At which point do I switch to OCN and track that inbound?

Halfway between VOR unless there is a "switch" symbol stating when to switch. Since the distance between SLI and OCN is 40nm, then switch at 20nm.

Take a look at PDZ V8 between SLI and PDZ for an example of the switch symbol.

[n65z]

Thank you. So, just to be clear...on the v8 between SLI and PDZ, the changeover would be at OLLIE?

[Keith Smith]

(This was my post I started hours ago but have been on the phone the whole time).

The airways are 4nm wide either side of the centerline except at extreme distances from the VOR where they get even wider.

In terms of switching over to OCN, it would be at the halfway point unless a COP (Changeover Point is defined).

See the Workshop on Enroute procedures for more detail.