Vor 7 Lwt

[Flysher]

Do any of you read IFR refresher? Its an excellent magazine and I highly recommend it to anyone looking to constantly challenge their IFR knowledge.

Usually every month they will pick out an interesting approach and discuss it. December talks about the VOR 7 into LWT. Below is a link to this plate.

http://204.108.4.16/d-tpp/0612/00231V7.PDF

My question is this, if one were cleared for the DME arc portion of this approach from the IAF, how exactly would you fly to that point? I would think that joining the arc anywhere inside of the 307 radial would be good enough, but what do you all think?

Another question maybe more for the ATC guys, is it legal to start an arc any place inside the IAF?

[tgrayson]

Originally Posted by Flysher

My question is this, if one were cleared for the DME arc portion of this approach from the IAF, how exactly would you fly to that point?

V611 lies on the 307 radial; seem likely you could only use that IAF if you were on the airway, since the fix doesn't have a name.

Originally Posted by Flysher

I would think that joining the arc anywhere inside of the 307 radial would be good enough, but what do you all think?

Technically no, because you need either vectors to final or begin the approach at an IAF, according to the FAA General Counsel's Office. There is a letter of interpretation to this effect.

Originally Posted by Flysher

Another question maybe more for the ATC guys, is it legal to start an arc any place inside the IAF?

That really isn't a question for ATC guys, because they generally don't know what's legal or not with regard to instrument approaches. That's "pilot stuff". However, I do know that ATC will often vector you to a portion of the arc inside the IAF and expect you to fly the approach from there on out. Legal? Arguably not, but done all the time in the real world.

This arc is pretty short; I'd rather not intercept it any closer than I had to, unless I had a lot of practice with this approach. I

[Flysher]

Well i found the answer to my own question

Cases in which an IAF is depicted as a radial crossing the arc with no corresponding intersection are usually coincided with airways that come off the VOR.

Still take a look at the approach, its got a bit of everything.

[Flysher]

thanks for the reply I think we pressed post near the same time.

Thanks for the info.

[MidlifeFlyer]

If you were cleared for the arc, you would have intercepted at the arc IAF. If you were coming from the south and overflew the VOR, you would fly outbound on the 307 until interepting it.

There =may= be a way for ATC to vector you to intercept an arc at other than an IAF, but in general you can only fly a DME arc approach from an IAF in the arc. It's not the best written, but here's what a 1994 FAA Legal opinion says on the subject (dealing with a non-radar environment):

==============================
First you ask whether an arriving aircraft must begin the SIAP at a published Initial Approach Fix (IAF). A pilot must begin a SIAP at the IAF as defined in Part 97. Descent gradients, communication, and obstruction clearance, as set forth in the U.S. Standard for Terminal Instrument Approach Procedures (TERPs), cannot be assured if the entire procedure is not flown.

You also ask whether a Distance Measuring Equipment (DME) arc initial approach segment can be substituted for a published IAF along any portion of the published arc. A DME arc cannot be substituted for a published IAF along a portion of the published arc. If a feeder route to an IAF is part of the published approach procedure, it is considered a mandatory part of the approach.
==============================

(...I was still typing when you guys were posting)

[Flysher]

Well now if you started it from the VOR then you would just fly 274 outbound and do the procedure turn.

I dont think you could start the arc from the VOR since the 307 radial doesnt depict an altitude or distance.

I could be wrong though

[tgrayson]

Originally Posted by Flysher

Well now if you started it from the VOR then you would just fly 274 outbound and do the procedure turn.
I dont think you could start the arc from the VOR since the 307 radial doesnt depict an altitude or distance.
I could be wrong though

I agree that without a specific clearance to do so, you could not fly outbound on the 307 to start the approach. It isn't part of a published route. You would need to pick your altitude carefully.