What is ILS CLASS in this airport NOTAM?

Question

I have seen this NOTAM for UAII /CIT SHYMKENT airport and they mention ILS CLASS for runway 10/28, Does anyone knows what it means?

NOTAM:

• NOTAM K3998/20: Shymkent Airport (UAII)

  K3998/20 NOTAMN

  Q) UAII/QICXX/I /NBO/A /000/999/4222N06929E005

  A) UAII B) 2008171542 C) PERM

  E) RWY 10/28 ILS CLASS:

  ILS GP I/C/2

  ILS LOC I/D/2

  REF AIP UAII AD 2.19

  CREATED: 17 Aug 2020 15:42:00

  SOURCE: EUECYIYN

Answer 1

This is a change in the ILS Facility Classification code. In your example the code is I/C/2 for ILS with GP, which means:

• The ILS category is CAT I
• Quality of Course C, which means localizer performance follows performance requirements until 100ft
• Integrity level 2 (see ICAO Annex 10, Volume I for details)

The changes can also be found in the Kazakhstan eAIP UAII AD 2.19.

Here is a detailed description of the three codes in the classification by ICAO:

ILS FACILITY CLASSIFICATION AND DOWNGRADING

The ILS facility classification system provides a more comprehensive method of describing ILS performance than the simple CAT I/II/III classification. An example of an ILS facility classification is “III/E/4”. ILS facility classification is described in Annex 10, Volume 1. A facility’s “class” of performance is defined by using three characters as follows:

a) The first group of characters (I or II or III) indicates conformance to the facility performance category standards contained in Annex 10, Volume I. This character indicates if the ground equipment meets a facility performance Category I, II or III.

b) The second group of a single character defines the ILS point (Figure C-1) to which the localizer conforms to the facility performance Category II/III course structure tolerances. These classifications indicate ILS conformance to a physical location on the approach or runway as follows:

1. A: 7.5 km (4 NM) before the threshold;
2. B: 1 050 m (3 500 ft) before the threshold (CAT I decision point);
3. C: Glide path altitude of 100 ft HATh (CAT II decision point);
4. T: Threshold;
5. D: 900 m (3 000 ft) beyond the threshold (facility performance category III requirement only);
6. E: 600 m (2 000 ft) before the runway end (facility performance category III requirement only).

c) The third group of a single character indicates the level of integrity and continuity of service. It is generally accepted, irrespective of the operational objective, that the average rate of a fatal accident during landing due to failures or shortcomings in the whole system, comprising the ground equipment, the aircraft and the pilot, should not exceed $1 \times 10^{–7}$. This criterion is frequently referred to as the global risk factor. In Category III operations, this objective should be inherent in the whole system. In this context it is of the utmost importance to endeavour to achieve the highest level of integrity and continuity of service of the ground equipment. Integrity is needed to ensure that an aircraft on approach will have a low probability of receiving false guidance; continuity of service is needed to ensure that an aircraft in the final stages of approach will have a low probability of being deprived of a guidance signal. Integrity and continuity of service requirements are defined in Annex 10, Volume I, Chapter 3, 3.1.3.12, for the localizer and Chapter 3, 3.1.5.8, for the glide path.

^{(ICAO Manual of All-Weather Operations)}