DME Arc question

[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]

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]

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!