Great Circle and VOR radial

[WhiteKnight]

hi

I´m not quite sure if I got this right.

Let`s assume we`re flying on a radial 70° of a VOR. That means we are following a great circle, right? Thus, if there is no wind we start with a heading of also 70° .In a few hundert miles, or whatever, and still on the radial we should fly on a heading of maybe 80° (on the nothern hemisphere). Is this so far correct?

That means we have to alter continously our course in order to stay on the radial, just hold the CDI-needle in the centre?

Any help would be much appreciated.

[peb]

radial = great circle
There is not much help becsuse all you said is right.

[WhiteKnight]

Thank you for your response,peb!

But this would mean, that the radial is not your exact magnetic course! But obviously we treat the radial like a magnetic course. Is this because the distances between the VORs are relatively short?

[scroggs]

Don't forget that VOR radials are limited by line-of-sight. The maximum range that you'll get a VOR signal at normal cruising altitudes is 200nm or so, and you'd be pretty daft to attempt to fly a radial at much beyond 120 miles. Unless you're in northern Canada, the magnetic heading required to track the radial won't change very significantly in 120 miles.

Scroggs

[Alex Whittingham]

Its a monster question, or, at least, a monster answer to a simple question.

If you are talking about the Radio Nav exam question that asks something like 'You are following a VOR radial, what sort of track are you flying?' The answer is 'a great circle'. In order to explain this properly I'll need to post up some diagrams which will have to wait 'till tomorrow.

[Old Smokey]

Radio waves follow Great Circles. VOR radials are radio waves, and therefore are great circles.

Unless you are flying exactly north or south, AND along an isogonal, the Magnetic Track will constantly change to achieve the said great circle.