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: Performance-Based Approach Classification Summary

  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?


  • $\begingroup$ I don't understand the colours' meaning on the last table. $\endgroup$ – Manu H Feb 4 at 8:54
  • $\begingroup$ I'm trying to transform the title in a question (as this is a Q&A website), but I'm unhappy with the formulation I have. What about "how can CatIII approach (according to ICAO classification) can be classified as type A (by EASA classification) and what minimas should I use?" $\endgroup$ – Manu H Feb 4 at 9:02
  • $\begingroup$ @ManuH Thank you for pointing that out. Maybe just 'How can Type A approach be CAT I/II/III' is enough? $\endgroup$ – Filip N. Feb 4 at 9:10

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.

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  • $\begingroup$ I know that Type A approaches aren't all the green rows. But part of them are (under Type A column). What are those? Why is the approach in LIRN Type B? DH is obviously more than 250 ft. $\endgroup$ – Filip N. Feb 4 at 0:59
  • $\begingroup$ @Filip N. Edited $\endgroup$ – Sami Feb 4 at 8:09
  • $\begingroup$ Ok, I think I got it. So Type A/B is about system minima and not about actual aerodrome operating minima. Thank you. $\endgroup$ – Filip N. Feb 4 at 8:19
  • $\begingroup$ @Filip N. , Can you explain the difference between System minima and actual AOM? $\endgroup$ – Shahab Mohd Jun 12 at 17:04
  • 1
    $\begingroup$ @ShahabMohd System minima is the lowest minima for a given approach system. For example, CAT 1 ILS system minima is 200ft above ground level. You can never have a lower CAT 1 ILS minima than that. The actual operating minima is determined for each runway and approach separately. Let's say that an airport has a CAT 1 ILS approach on RWY24. The procedure planner would see if 200ft minima is enough for a safe go-around for that runway. If not (because of obstacles usually) the minima will be raised higher to clear the obstacles. That's how we get the "actual minima". $\endgroup$ – Sami Jun 13 at 11:40

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