Final approach course

rdsoxpilot

rdsoxpilot

Well-Known Member
I imagine most of yall could chaulk this up as a stupid question but as my mentor would say "there's no such thing as a stupid question" so here goes:

In a basic VOR approach, why are some final approach courses offset to the runway? I know that some VOR's are offset because they're obviously offset from the runway, and I undestand obstacle clearance & what not. But here's a good example of an approach with no FAF and no reason that I can find that has the final approach course roughly 15 degrees of course of centerline.

http://204.108.4.16/d-tpp/0812/00998V9R.PDF

Thoughts & comments are greatly appreciated. Cheers.
 
It is my understanding that the final approach course is once you turn inbound?
 
I'm not an approach designer, but my best guess is with the VOR to the south of the two runways, they have it set up so that you would pass the final for either 9L or 9R. If you were flying a final approach course (I'm not sure without a 10-9) of say "090" then you would be perfectly lined up to land on the grass near the VOR, not expecting an offset. It can be difficult to see the runway in low visibility, so expecting to find the runway at an offset helps.
 
Same disclaimer as the Commodore, but I'd add the final approach course delivers you to the approach lighting system for the runway.

By flying at an angle to the runway you actually end up closer to the lights.

Cheers
George
 
georgetg said:
Same disclaimer as the Commodore, but I'd add the final approach course delivers you to the approach lighting system for the runway.

By flying at an angle to the runway you actually end up closer to the lights.

Cheers
George
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hi george:D how's them big jets treatin' you?
 
I know that some VOR's are offset because they're obviously offset from the runway, and I undestand obstacle clearance & what not. But here's a good example of an approach with no FAF and no reason that I can find that has the final approach course roughly 15 degrees of course of centerline.
Click to expand...

I think you may have answered your own question. Even if it the VOR is 'slighty' offset you will not get an approach on centerline.

Think of the ILS. That will take you to centerline on a specific rw because that is the nature of its' setup. Unless the VOR is installed dead center of a rw, I don't see how an final course that you speak of could occur.
 
rdsoxpilot said:
I imagine most of yall could chaulk this up as a stupid question but as my mentor would say "there's no such thing as a stupid question" so here goes:

In a basic VOR approach, why are some final approach courses offset to the runway? I know that some VOR's are offset because they're obviously offset from the runway, and I undestand obstacle clearance & what not. But here's a good example of an approach with no FAF and no reason that I can find that has the final approach course roughly 15 degrees of course of centerline.

http://204.108.4.16/d-tpp/0812/00998V9R.PDF

Thoughts & comments are greatly appreciated. Cheers.
Click to expand...

On the right hand side of the plate, you can see the VOR placed on the west side of the airport. That is the only reason why. They couldn't/didn't align it with a runway, for whatever reason.
 
rdsoxpilot said:
no reason that I can find that has the final approach course roughly 15 degrees of course of centerline.
Click to expand...

The FAC must intercept the extended runway centerline within a distance of 3000 feet. A straight-in at this airport would never intercept the extended runway centerline.
 
tgrayson said:
The FAC must intercept the extended runway centerline within a distance of 3000 feet. A straight-in at this airport would never intercept the extended runway centerline.
Click to expand...

This is exactly right. In order to qualify this approach as a straight in, the final approach course must cross the centerline of the runway BEFORE the threshold (out to 3000 feet, as Tgrayson said). If it doesn't, then the approach is circling only.
 
Nice call, didn't know that regulation, is that an FAA requirment? And I'm guessing in an extreme circumstance where let's say the VOR is a mile south of the airport then the FAC would be too drastic for a straight-in and would be qualified as a circling approach?
 
rdsoxpilot said:
I imagine most of yall could chaulk this up as a stupid question but as my mentor would say "there's no such thing as a stupid question" so here goes:

In a basic VOR approach, why are some final approach courses offset to the runway? I know that some VOR's are offset because they're obviously offset from the runway, and I undestand obstacle clearance & what not. But here's a good example of an approach with no FAF and no reason that I can find that has the final approach course roughly 15 degrees of course of centerline.

http://204.108.4.16/d-tpp/0812/00998V9R.PDF

Thoughts & comments are greatly appreciated. Cheers.
Click to expand...

My guess would be because its a non percision approach. it brings you to the runway as long as your within minimums, so it doesnt have to be in line with the runway.
 
rdsoxpilot said:
Nice call, didn't know that regulation, is that an FAA requirment?
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It's a TERPs requirement. That's a set of requirements that instrument approaches must conform to, sort of like our highway system must conform to a consistent set of design considerations. There are some exceptions to the requirement for "operational advantage", which would usually mean lower minimums.

And I'm guessing in an extreme circumstance where let's say the VOR is a mile south of the airport then the FAC would be too drastic for a straight-in and would be qualified as a circling approach?
Click to expand...
Yes.
 
There's a state park to the south of the approach to those runways, but it's farther south than a strait in approach would be.

I would say, as the rest of the guys, that it has more to do with the placement of the VOR.
 
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