DME arcs

[CloudyIFR]

Can ATC vector an aircraft onto a DME arc in a radar environment anywhere upon it's length?

Can ATC vector an aircraft onto a DME arc in a non-radar environment anywhere upon it's length?

What is the maximum turn in degrees that you're allowed to turn upon an arc?

Here's an approach with DME Arc's.
http://204.108.4.16/d-tpp/0602/00192I27.PDF

So if I'm inbound on the 053 radial can I turn left onto the arc then proceed inbound on the ILS in a radar environment? How about in a non-radar environment?

From what I've been hearing lately from the Part 121 guys is that the only place to enter a DME arc is at the very end. Okay, I think I understand that intercepting it anywhere upon it's length won't guarantee the TERPS descent gradient. Fair enough.

However, if I'm inbound on the 053 radial say at 30nm and wish to fly the arc and request direct to the HLN 336 radial at 15nm with my trusty RNAV, when I arrive there I'll have about a 180 degree turn to get onto the arc. Depending on the airplane I'm flying, i.e. groundspeed, I may not stay in protected airspace during the turn but once I get turned around I'll maintain the descent gradient for the approach. But wouldn't it be much safer to turn onto the arc at the 053 radial since it's only a 90 degree turn, I'd still have plenty of time to make a normal descent to the altitudes on the arc.

I realize I could just come to the VOR then out to the end of the arc but I'm trying to understand fully why I can't join the arc anywhere upon it's length if I decide as the Capt that I can provide normal descents onto the arc and the approach.

I hope I wrote this clearly enough to start a nice discussion about this.

Of course any references would be nice.

Thanks
CloudyIFR

 

[avbug]

Nov. 28, 1994
Mr. Tom Young, Chairman
Charting and Instrument Procedures Committee
Air Line Pilots Association
535 Herndon Parkway
Herndon, VA 22070
Dear Mr. Young

This is a clarification of our response to your letter of August 23, 1993. In that letter you requested an interpretation of Section 91.175 of the Federal Aviation Regulation (FAR) (14 CFR Section 91.175). You address the necessity of executing a complete Standard Instrument Approach Procedure (SIAP) in a non-radar environment while operating under Instrument Flight Rules (IFR). Our response assumes that each of the specific scenarios you pose speaks to a flight conducted under IFR in a non-radar environment.

Section 91.175(a) provides that unless otherwise authorized by the Administrator, when an instrument letdown to a civil airport is necessary, each person operating an aircraft, except a military aircraft of the United States, shall use a standard instrument approach procedure prescribed for the airport in Part 97.

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.

Finally, you ask whether a course reversal segment is optional "when one of the conditions of FAR section 91.175(j) is not present." Section 91.175(j) states that in the case of a radar vector to a final approach course or fix, a timed approach from a holding fix, or an approach for which the procedures specifies "no procedure turn," no pilot may make a procedure turn unless cleared to do so by ATC.

Section 97.3(p) defines a procedure turn, in part, as a maneuver prescribed when it is necessary to reverse direction to establish the aircraft on a intermediate or final approach course. A SIAP may or may not prescribe a procedure turn based on the application of certain criteria contained in the TERPs. However, if a SIAP does contain a procedure turn and ATC has cleared a pilot to execute the SIAP, the pilot must make the procedure turn when one of the conditions of Section 91.175(j) is not present.

If you have any questions regarding this matter, please contact Patricia R. Lane, Manager, Airspace and Air Traffic Law Branch, at (202) 267-3491.

Sincerely,

/s/
Patricia R. Lane
for Donald P. Byrne
Assistant Chief Counsel
Regulations Division

 

[81Horse]

Can ATC vector an aircraft onto a DME arc in a non-radar environment anywhere upon it's length?

 

[avbug]

Yer killin me, horse.

 

[81Horse]

I can't help myself, 'bug -- I was educated by nuns.

 

[satpak77]

Avbug - what career field are you in?

 

[Catbert]

Dang avbug, where do you find all these interpretations? Where I work we're always talking about these beasts, but can never find them. You pull them out like you've got a stack of them on your desk.

Seriously, is there a central place to find these things, or do I have to keep stumbling across them here and there?

 

[avbug]

I used to have fantasies about being educated by nuns.

I don't work. That's a misconception. I get paid, but I don't work.

If you get ASA's Flight Library (the pro edition), you'll have all FAA pubs and a bunch of manuals and books all on one CD, for eighty bucks. Same one the FAA uses. Makes searches fast, copying information quick, and saves having to lug around a bunch of paper. Although in honesty, I prefer paper. The more I write in the margins, the less I can see of my computer screen. Presently the viewing area is about the size of a matchbook.

Satpak, I fly, but you're the first to call this wreck of mine a "career." Thank you, anyway.

 

[flx757]

Dang avbug, where do you find all these interpretations? Where I work we're always talking about these beasts, but can never find them. You pull them out like you've got a stack of them on your desk.

Seriously, is there a central place to find these things, or do I have to keep stumbling across them here and there?

Not a stack of them...just a reference CD (and update subscription) issued by this company:

http://www.summitaviation.com/

(Of course, you have to have nothing better to do with your time than look this stuff up, then copy and paste on message boards such as this... )

 

[Catbert]

Thanks avbug and flx757, I didn't know such a disk existed. Very helpful. I feel an aviation-related expenditure coming on.