Title 14 of the Code of Federal Regulations (14 CFR) part 97 CAT II or III SIAP:
Appendix B
a. I, II, or III. The first character indicates conformance to the Facility Performance CAT standards contained in International Civil Aviation Organization (ICAO) Annex 10, unless superseded by an FAA directive.
b. A, B, C, T, D, or E. The second character defines the ILS point to which the localizer conforms to the Facility Performance CAT III course structure tolerances. These classifications indicate ILS conformance to a physical location on the approach or runway as follows:
· A: 4 nautical miles (NM) before the threshold,
· B: 3,500 feet before the threshold (CAT I decision point),
· C: Glidepath altitude of 100 feet height above touchdown (HAT) (CAT II decision point),
· T: Threshold,
· D: 3,000 feet beyond the threshold (CAT III requirement only), and
· E: 2,000 feet before the runway end (CAT III requirement only).
c. 1, 2, 3, or 4. The third character indicates the minimum level of integrity and Continuity of Service (CoS) given in Table 1. Refer to the current edition of Order JO 6750.57, Instrument Landing System Continuity of Service Requirements and Procedures.
(1) Level 1-rated ILS equipment supports low-visibility operations for which positioning guidance below approximately 200 feet height above threshold (HATh) is supplemented by other means, such as visual cues or advanced avionics.
(2) Level 2-rated ILS equipment supports reduced visibility operations for which positioning guidance below 100 feet HATh is supplemented by other means, such as visual cues.
(3) Level 3-rated ILS equipment supports operations that place a high degree of reliance on ILS guidance for positioning through touchdown.
(4) Level 4-rated ILS equipment supports operations that place a high degree of reliance on ILS guidance throughout touchdown and rollout, or for low-visibility takeoff operations that require a localizer for lateral guidance throughout the takeoff roll.
Table 1. Minimum Localizer and Glideslope Integrity and Continuity Levels
