Is this turn legal ?

C

c310flyr

Pre-Flight
Joined
Oct 26, 2010
Messages
46
Display Name
Display name:
c310flyr
Please reference this approach at Auburn, Ca

https://aeronav.faa.gov/d-tpp/2108/09143R7.PDF


I noticed that from Rozzy to CITXU, the leg is labeled nopt, yet it is a 098 degree turn.

The turn from the other side is even more.

I thought turns like these had to be 90 degrees or less

Any thoughts ?
 
TERPS 2-4-3. Initial Approach Segments Based on Straight Courses and Arcs with PCG. a. Alignment. (1) Straight courses. The angle of intersection between two successive initial approach courses and the angle of intersection between an initial approach course and an intermediate course must not exceed 120 degrees. When the angle between an initial approach course and intermediate course exceeds 90 degrees, a radial or bearing which provides at least 2 NM of lead must be identified to assist in leading the turn onto the intermediate course (see figure 2-4-1).
 
TERPS (FAAO 8260.3) only applies to RNAV procedures when it is not otherwise superseded by FAAO 8260.58, which is the "TERPS" for RNAV. 8260.58B, para 1-2-5a(3) has the maximum of 90 degrees for RNAV procedures.

However, this was not always the case. Previously, the same (or similar) limitations applied for RNAV as non-RNAV. I would say that this was up until maybe 10-15 years ago, when the 90-degree requirement was requested by users due to some issues with FMSes (I believe - @aterpster might have more detail on that).

A procedure that has not had a major amendment (an up-numbering from Orig to 1 to 2, etc.) in a while might have been designed under the old rules.

So is it "legal"? Yes it's legal for you to fly it. It would no longer be able to be designed that way without a waiver, but it's a "legal" procedure.
 
RussR said:
However, this was not always the case. Previously, the same (or similar) limitations applied for RNAV as non-RNAV. I would say that this was up until maybe 10-15 years ago, when the 90-degree requirement was requested by users due to some issues with FMSes (I believe - @aterpster might have more detail on that).
Click to expand...
I do. We (NBAA) demonstrated to AFS-410 at a charting forum a few years ago that modern flight management systems could handle an RNAV course change of up to 120 degrees quite well, at least at terminal speeds. Our poster child was the KDLN RNAV Rwy 17, arriving at JOXIT feeder fix on V343 from the south (103 degree course change). Didn't matter, AFS-410 had its collective mind made up; i.e., arriving in that manner requires flying the arrival holding pattern. And, that requires more interface with ATC because arrival holding patterns require an additional ATC clearance. (sigh...)
 
aterpster said:
I do. We (NBAA) demonstrated to AFS-410 at a charting forum a few years ago that modern flight management systems could handle an RNAV course change of up to 120 degrees quite well, at least at terminal speeds. Our poster child was the KDLN RNAV Rwy 17, arriving at JOXIT feeder fix on V343 from the south (103 degree course change). Didn't matter, AFS-410 had its collective mind made up; i.e., arriving in that manner requires flying the arrival holding pattern. And, that requires more interface with ATC because arrival holding patterns require an additional ATC clearance. (sigh...)
Click to expand...
Was that in the Charting Group or the Instrument Procedures Group? Do you remember the Issue Number?
 
You must log in or register to reply here.
Back
Top