ICAO and EASA classification of instrument approaches

Question

ICAO distinguishes approaches operations based on DH between 'Type A' (DH >= 250 ft) and 'Type B' (DH < 250 ft), which are further divided into subcategories. From the Annex 6 — Operation of Aircraft Part I:

a) Type A: a minimum descent height or decision height at or above 75 m (250 ft); and

b) Type B: a decision height below 75 m (250 ft). Type B instrument approach operations are categorized as:

1. Category I (CAT I): a decision height not lower than 60 m (200 ft) and with either a visibility not less than 800 m or a runway visual range not less than 550 m;
2. Category II (CAT II): a decision height lower than 60 m (200 ft) but not lower than 30 m (100 ft) and a runway visual range not less than 300 m;
3. Category IIIA (CAT IIIA): a decision height lower than 30 m (100 ft) or no decision height and a runway visual range not less than 175 m;
4. Category IIIB (CAT IIIB): a decision height lower than 15 m (50 ft) or no decision height and a runway visual range less than 175 m but not less than 50 m; and
5. Category IIIC (CAT IIIC): no decision height and no runway visual range limitations.

Instrument approach procedures are further classified as follows:

Non-precision approach (NPA) procedure. An instrument approach procedure designed for 2D instrument approach operations Type A.

Approach procedure with vertical guidance (APV). A performance-based navigation (PBN) instrument approach procedure designed for 3D instrument approach operations Type A.

Precision approach (PA) procedure. An instrument approach procedure based on navigation systems (ILS, MLS, GLS and SBAS CAT I) designed for 3D instrument approach operations Type A or B.

If I understand correctly, EASA would like to implement similar concept (as stated in 'Notice of Proposed Amendment 2018-06(C)'). On page 51, there is a summary table with classification of approaches:

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1. From the table above, how can Category I/II/III approach be 'Type A' approach (green rows)? I thought that from the definition, only 'Type B' approaches have subcategories.
2. What kind of approach would be LIRN ILS Z RWY 06 (see the chart below)? What kind of planning minima should I use?

Answer 1

First, you're reading the EASA table wrong. Type A approaches are not all the green rows, they're the vertical column that says "Type A, 2D or 3D" that covers all the specific column of all the green rows and the blue also. On the right side of that column, you see Type B approaches, divided to subcategories. All of those being 3D approaches.

Second, the approach you are asking about is a precision approach. Type B 3D approach if we want to use the new terms. It's an ILS-approach, it has a vertical flight path guidance. You should use precision approach planning minima. It does have a higher minima than ILS usually does. The higher minima is most likely because of nearby high terrain influencing the go-around requirement.

I would say it's Type B 3D because it's Cat 1 ILS, therefore it's a precision approach and it must be a precision runway. The lowest possible DH for Cat 1 ILS is 200ft. With these facts I would place it in the given category. Although this particular approach minima is higher, it is not because of the approach it self, but rather because of obstacles.

Answer 2

According to EASA Part Air Operations (GM3 CAT.OP.MPA.182(c))

• Amongst other things the lowest DH for an instrument approach operation is determined by the system minima for the facility and the obstacle clearance height (OCH). The resulting DH determines the type of approach operation (type A or B).

• If the DH is 250 ft or more, it will be a type A approach operation; if the DH is less than 250 ft, it will be a type B approach operation.

• So, while ILS approaches to most runways may be conducted as type B approach operations, difficult obstacle situations, driving up the DH to 250 ft or higher, will result in type A approach operations.

Answer 3

The new system is quite disturbing. My following thoughts will be in force October 30th 2022...

Step 1: Discover type of approach A or B. In your example given in LIRN, your DH is 395ft. According to EASA 965/2012 definition (120d & 120e) [Amendmt. 2021-2237]. The key number here is DH, if DH is at or above 250 is type A, if DH is lower is type B. Conclusion step 1: your approach has to be classified as Type A.

Step 2: kind of instrument approach procedure Same regulation and amendment but different definition. Now we are playing with definition 69e. On type A we've got 3 different kind of approach procedures (NPA, APV or PA) NPA is 2D approach, APV is 3D approach based on PBN and PA is 3D approach with conventional aids or SBAS. Conclusion step 2: it is clearly a 3D approach based on conventional aids (ILS).

So you're approach should be Type A - PA approach.

Hopping it's help a bit.