I am studying the Satellite Based Augmentation System (SBAS) from PANS OPS manual 8168, Volume II, sixth edition, and I have a problem concerning the criteria of SBAS-NPA.
In Part III, Section 3, Chapter 5 called "SBAS NON-PRECISION APPROACH, APPROACH WITH VERTICAL GUIDANCE AND PRECISION APPROACH CAT I PROCEDURES", it states:
5.1.1 Procedure construction This chapter describes the SBAS criteria for the NPA, APV 1 and PA CAT I procedure segment, which are specific to the performance of SBAS systems. Throughout this Chapter SBAS OAS refers to both SBAS APV OAS and SBAS CAT I OAS. The APV or CAT I segment includes the final approach, and the initial and the intermediate phases of the missed approach segment. The other phases of flight are generic in character and are presented in Part III, Section 3, Chapter 1 and Chapter 2.
However, a few chapters before and, specifically, in Chapter 3 called "NON-PRECISION APPROACH PROCEDURES", it describes the rules concerning the Non-Precision approaches in general.
3.1.1.1 This chapter describes the non-precision approach criteria for RNP APCH procedures.
The problem is that it's not clear to me which criteria to follow. Do the rules of the general Non-Precision approaches also apply to SBAS Non-Precision procedures, or the latter follows its own distinct rules covered solely in Chapter 5?
Another issue that troubles me is that the topics discussed in this manual are scattered through its sections, without any easy way to track the desired information. For example, in Volume I, it states:
1.2.4.2 Straight-in approach. Wherever possible, a straight-in approach will be specified which is aligned with the runway centre line. The pilot should be aware that for non-precision approaches, a straight-in approach is considered acceptable if the angle between the final approach track and the runway centre line is 30° or less
On the other hand, in the aformentioned Chapter 5 of Volume II, Part III, where it discusses SBAS, it has a special paragraph discussing the use of SBAS approach with offset alignment.
5.7.1.1 The final approach track shall intersect the runway extended centre line:
a) at an angle not exceeding 5°; and
b) at a point where the nominal glide path reaches a height called intercept height of at least 55 m (180 ft) above threshold.
This becomes really confusing, since I can not comprehend which rules apply exclusively for SBAS NPA and which rules are supposed to be followed in every case of non-approach procedure.
I would be grateful if someone could help me clear this out and read the manual the way it is intended by their authors.
