Categories of Aeroplanes and Approaches

Aeroplanes are put into 5 different categories depending on their speed at threshold (Vat) which is equal to the stalling speed (Vso) x 1.3 .



Minimum Visibility and MDH for circling approaches

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Non Precision approach

Operator must make sure that the system minima for non-precision approach procedures, based on the following nav aids, are not lower than;

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Precision Approach - CAT I

- Precision instrument approach and landing (using ILS, MLS or PAR)
- Decision height not lower than 200ft and RVR not lower than 550m

A pilot shall not continue the approach below the DH unless at least one of the following is distinctly visible and identifiable;

- Elements of the approach light system
- Threshold
- Threshold markings / lights
- Visual glide slope indicator
- Touchdown zone (markings / lights)
- Runway edge lights

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Precision Approach - CAT II

- Precision instrument approach and landing (using ILS and MLS)
- Decision height not lower than 100ft and RVR not lower than 300m

A pilot shall not continue the approach below the DH unless visual reference containing a segment of at least 3 consecutive lights (being centre line line of approach lights, touchdown zone lights, runway centre line or edge lights, ...) can be maintained.

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Precision Approach - CAT III

This category is subdivided in A, B and C;

A = Precision instrument approach and landing using ILS or MLS with a DH not lower than 100ft, and RVR not lower than 200m

B = Precision instrument approach and landing using ILS or MLS with DH lower than 50ft or no DH and a RVR not lower than 75m

C = Precision instrument approach and landing using ILS or MLS with no DH and no RVR requirements

! When the DH and RVR do not fall within the same category, the RVR will determine in which category the operation is to be considered

Operations with no decision height (DH)

Can only be conducted if;

- Authorised in the AFM
- Approach aid and aerodrome facilities can support such operations
- Operator has an approval for CAT III operations (with no DH)

Visual Reference

CAT IIIa and CAT IIIb with fail-passive flight control systems = A pilot cannot continue under the DH unless visual reference containing a segment of at least 3 consecutive lights can be maintained

CAT IIIb with fail-operational flight control systems (using a DH) = A pilot cannot continue under the DH unless visual reference containing at least 1 centreline light can be maintained

CAT IIIb with no DH = No requirement for visual contact with the runway prior to touchdown

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Summary Chart