DME Arc question

[FlyboyZR1]

If you're cleared for an approach and nowhere near an IAF, can you legally just hop onto the arc at any point and follow it in, or do you have to proceed all the way to an IAF first? My guess is that if you're being radar vectored you could pick up the arc at any point, but if not then you must proceed to an IAF.

[meritflyer]

Originally Posted by FlyboyZR1

If you're cleared for an approach and nowhere near an IAF, can you legally just hop onto the arc at any point and follow it in, or do you have to proceed all the way to an IAF first? My guess is that if you're being radar vectored you could pick up the arc at any point, but if not then you must proceed to an IAF.

You could be vectored onto the arc at any position ATC deems fit. If you were cleared for the approach w/out being vectored you'd proceed to an initial approach fix, arc, intercept the final approach course and fly it.

[AlWaYs HiGh]

Originally Posted by meritflyer

You could be vectored onto the arc at any position ATC deems fit. If you were cleared for the approach w/out being vectored you'd proceed to an initial approach fix, arc, intercept the final approach course and fly it.

Just joining an arc 'somewhere' along it is a bad idea...if ATC ever tries to do that, which i doubt they will, i'd say it would be best to decline it.

[seagull]

Correct. There is a FAA AGC letter of interp that says you must start at an IAP absent radar vectors to the FAC.

[JEP]

Originally Posted by AlWaYs HiGh

Just joining an arc 'somewhere' along it is a bad idea...if ATC ever tries to do that, which i doubt they will, i'd say it would be best to decline it.

Granted it is in a training environment, but It happens all the time here in MSP. At KFCM if you are W/SW of the field they will vector you onto the Arc. Shoot, we request it that way.......The IAF is the 170 radial and if I am W/SW of the field, I have no desire to waste the time/gas/$$$ to hit the IAF at 170. Give me vectors, Ill ride the arc and shoot the approach...

[Dugie8]

Originally Posted by seagull

Correct. There is a FAA AGC letter of interp that says you must start at an IAP absent radar vectors to the FAC.

Which is total BS (not you Gul, the ruling), I can be vectored to anywhere on a approach (within reason) but I cannot intercept an ARC anywhere but the defined beginings. Total crap, luckily I have never had to use an ARC in the realworld.

[meritflyer]

Being vectored onto an arc happens all the time in PHX during training.

[MidlifeFlyer]

Originally Posted by Dugie8

Total crap, luckily I have never had to use an ARC in the realworld.

Interesting thought: the way something I've never done in real life works in real life is "total crap."

Seagull, do you have that particular interpretation handy? I've seen one that suggests what you say, but it's limited to a non-radar environment.

[clumpinglitter]

Originally Posted by JEP

Granted it is in a training environment, but It happens all the time here in MSP. At KFCM if you are W/SW of the field they will vector you onto the Arc. Shoot, we request it that way.......The IAF is the 170 radial and if I am W/SW of the field, I have no desire to waste the time/gas/$$$ to hit the IAF at 170. Give me vectors, Ill ride the arc and shoot the approach...

I heard about someone flying the VOR/DME-27 into ANE. He was flying southbound, and when he was cleared for the approach, he started to fly back north toward the IAF. ATC asked where he thought he was going -- the controller expected him to just join the arc southbound.

-C.

[FlyboyZR1]

Originally Posted by AlWaYs HiGh

Just joining an arc 'somewhere' along it is a bad idea...if ATC ever tries to do that, which i doubt they will, i'd say it would be best to decline it.

Unless I'm getting paid by the hour I'm not going to go out of my way to hit an IAF if I don't have to. One of the nice things about an arc is that you can join at any point while being radar vectored.

Thanks for the replies everyone.

[Dugie8]

Originally Posted by MidlifeFlyer

Interesting thought: the way something I've never done in real life works in real life is "total crap."

Well, in my opinion it is. We get vectored to approach courses all the time, but I can't get vectored to an ARC, total crap, luckily, I have not done them ever in "non" training flying.

No need to get snippy.

[MidlifeFlyer]

Originally Posted by Dugie8

Well, in my opinion it is. We get vectored to approach courses all the time, but I can't get vectored to an ARC, total crap, luckily, I have not done them ever in "non" training flying.

No need to get snippy.

Sorry.

Ever think that there's a reason you have not done one in a non-training flight? Chances are that if ATC is using radar vectors, it will be to a final approach course and not to an arc anyway - faster and easier for you and for them. (I'm curious, there's a bunch of piloting experience here - has anyone here received radar vectors to a DME arc in the "real world?")

I suspect that if you're in circumstances where you'd =need= to actually use an arc, the chances are pretty good that there is an obstruction or airspace issue that would make interception other than at the IAF problematic anyway. Besides, ever notice that those arc IAFs tend to be right on the airway or feeder route you'd be approaching on anyway.

(BTW, I still don't know if vectors to the arc are prohibited or not)

[meritflyer]

Originally Posted by MidlifeFlyer

(I'm curious, there's a bunch of piloting experience here - has anyone here received radar vectors to a DME arc in the "real world?")

Only on a practice approach did I have vectors to an arc. I was told something to the extent of this "Cessna 1234, turn left heading X, vectors for the 10 DME arc east off VOR X"

I complied. About half way into the arc, I was given a new heading to intercept the ILS. My belief was it was for spacing.

[MidlifeFlyer]

Originally Posted by meritflyer

Only on a practice approach

That's what I mean. Me too. For practice.

I don't even mean whether folks were vectored to the arc other than to an IAF. Just the use of a DME arc (other than for practice) where vectors were involved in the approach to the arc itself rather than a clearance via an airway or transition route.

In the real (not for practice world), Dugie suggests that if ATC can't vector you to intercept the arc other than at an IAP, it's "crap."

I'm wondering whether the "vectors to the arc" scenario even really exists outside of practice to begin with. If radar vectors are available and being used, I have a hard time figuring out why anyone - ATC or a pilot, would fly an arc, except for practice.

[fish314]

The only scenario that I can think of where this might happen, "in the real world" might be to an airport with a really strange approach like this: http://204.108.4.16/d-tpp/0608/05222VDTZ15.PDF (VOR/DME Rwy 15 at Martin State, Baltimore MD).

The whole approach is an arc, so I wonder if you could be vectored to "final" right on the arc?

I don't have an answer for this, just muddying the waters.

I have picked up approaches on the arc at points other than the IAF, but again, it was in the training environment. And I have to ask specifically for what I want to be able to do it. Haven't ever done it "in the real world".

[meritflyer]

Well, lets post it in the ATC forum to see what the controllers say.. see you there.

[clumpinglitter]

Originally Posted by meritflyer

Well, lets post it in the ATC forum to see what the controllers say.. see you there.

Hey ... smart!!

-C.

[seagull]

I have that interp at home, but not on my computer right now.

[meritflyer]

can you post it?

[FOD]

I asked this question once when visiting phoenix tracon. He gave me a funny look and said "i guess its possible, but have never seen it done".

[seagull]

U.S. Department of Transportation
Federal Aviation Administration

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 C.F.R. 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 IAP
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.

It 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

[TonyC]

Originally Posted by seagull

Correct. There is a FAA AGC letter of interp that says you must start at an IAP absent radar vectors to the FAC.

What the letter addresses is "executing a complete Standard Instrument Approach Procedure (SIAP) in a non-radar environment while operating under Instrument Flight Rules (IFR)." What it says is that in a non-radar environment, any approach must be commenced from an IAF, and a complete approach procedure must be accomplished.

To the point of the DME arc, the letter specifically says that intercepting a DME arc does NOT susbtitute for an IAF.


HOWEVER, you must remember that the basic underlying assumption of these interpretations is that we're talking about a NON-RADAR environment. Nothing in this letter precludes ATC from vectoring you (in a radar envionment, of course) to join the published arc and continue the approach from there. There is NO requirement, as your post states, to vector to only the Final Approach Course.




The idea to carry this conversation to the "Ask an ATC Controller" Forum was a good - - unfortunately the thread was hijacked and sent to the Lav. If you're interested in how it turned out... Vectors to an arc for an approach





.

[seagull]

Originally Posted by TonyC

What the letter addresses is "executing a complete Standard Instrument Approach Procedure (SIAP) in a non-radar environment while operating under Instrument Flight Rules (IFR)." What it says is that in a non-radar environment, any approach must be commenced from an IAF, and a complete approach procedure must be accomplished.

To the point of the DME arc, the letter specifically says that intercepting a DME arc does NOT susbtitute for an IAF.


HOWEVER, you must remember that the basic underlying assumption of these interpretations is that we're talking about a NON-RADAR environment. Nothing in this letter precludes ATC from vectoring you (in a radar envionment, of course) to join the published arc and continue the approach from there. There is NO requirement, as your post states, to vector to only the Final Approach Course.

The idea to carry this conversation to the "Ask an ATC Controller" Forum was a good - - unfortunately the thread was hijacked and sent to the Lav. If you're interested in how it turned out... Vectors to an arc for an approach



.

I must have been tired when I wrote that previous. I agree, ATC could vector you to intercept the arc. Can't imagine why they would, as I would guess it would be a nuisance for them and confusing to everyone involved, but I guess they could if they wanted to!

As for the other thread, I think I'll pass on one that diverged so badly that it ended up in the lav!