There has been a simplification in the categorization of instrument landing systems. CAT 3A and CAT 3B previously referred to different levels of precision and minimums for landing in low visibility conditions. Now, they’ve been consolidated into two categories: CAT 3 with Decision Height (DH) and CAT 3 without DH.
Cat 3 operations are now subdivided as:
A. precision instrument approach and landing using ILS with:
– decision height lower than 100 ft or no decision height; and
– visual range not less than 175 m.
B. A precision instrument approach and landing using ILS with:
– a decision height lower than 50 ft, or no decision height; and
– a visual range lower than 175 m but not less than 50 m.
Note: Where the decision height (DH) and runway visual range (RVR) do not fall within the regulatory requirements of same category, the RVR will determine in which Category the operation is to be considered.
Operations with decision height
Operator must ensure that the decision height is not lower than:
– the minimum decision height specified in the AFM, if stated; or
– the minimum height to which the precision approach aid can be used without the
required visual reference; or
– the decision height to which the flight crew is authorised to operate.
Operations with No Decision height
Operator must ensure that operations with no decision height may only be conducted if:
– the operation with no decision height is authorised in the AFM; and
– the approach aid and the aerodrome facilities can support operationswith no
decision height; and
– the operator has an approval for CAT III operations with no decision height.
Note: In the case of a CAT III runway it may be assumed that operations with no decision height can be supported unless specifically restricted as published in the AIP or NOTAM.
Visual reference for CAT 3 operations
Case 1
For Category III operations conducted with fail-passive flight control systems a pilot may not continue an approach below the decision height, unless a visual reference containing a segment of at least three consecutive lights being the centreline of the approach lights, or touchdown zone lights, or runway centreline lights, or runway edge lights, or a combination of these is attained and can be maintained. For Airbus A320 aircraft, this can be checked as CAT 3 SINGLE FMA status.
Case 2
For Category III operations conducted either with fail-operational flight control systems or with a fail operational hybrid landing system using a decision height a pilot may not continue an approach below the decision height, unless a visual reference containing at least one centreline light is attained and can be maintained. For Airbus A320 aircraft, this can be checked as CAT 3 DUAL FMA status.
Case 3
For Category III operations conducted either with fail-operational flight control systems or with a fail operational hybrid landing system without a decision height, there are no requirements for a visual verification prior to landing. For Airbus A320 aircraft, this can be checked as CAT 3 DUAL FMA status.
