Aerodrome Operating Minima and Instrument Approach Procedures
This domain tests how minima are built and applied: approach categories, DH/MDH and RVR, precision, APV, non-precision and circling approaches, low-visibility take-off, and the approach ban. Items often give a reported RVR group and ask whether the approach may be started or continued.
Operator minima (CAT.OP.MPA.110)
- The operator establishes aerodrome operating minima for each approach, approved by the authority and never lower than the minima set by the State of the aerodrome.
- Components: DH or MDH, RVR or converted meteorological visibility (CMV), and the required visual reference.
- Aircraft approach category from Vat: A below 91 kt, B 91 to 120 kt, C 121 to 140 kt, D 141 to 165 kt, E above 165 kt; circling minima increase with category.
Approach types and lowest figures
- CAT I: DH not below 200 ft, RVR not below 550 m.
- CAT II: DH 100 ft, RVR 300 m; CAT IIIA RVR 200 m, IIIB 75 m, IIIC none, each requiring specific airborne and ground equipment.
- Low-visibility take-off: 400 m unless approved lower, down to 125 m with runway centreline lighting and required RVR reports.
Commencement and continuation (CAT.OP.MPA.305)
- The approach may not be commenced past the final approach fix or outer marker if the reported RVR or visibility is below minima; this is the approach ban.
- Once past that point the approach may be continued even if RVR falls, but a go-around is required at DA/DH if the required visual reference is not obtained.
- Where touchdown zone, mid-point and stop-end RVR are reported, the touchdown zone value is controlling for the decision.
Worked example
An ILS CAT I with DH 200 ft and RVR 550 m. Reported RVR touchdown 500 m, mid 400 m, stop-end 450 m. As the aircraft reaches the outer marker the touchdown zone value of 500 m is below 550 m, so the approach cannot be commenced. If instead the aircraft is already inside the outer marker when the RVR drops to 350 m, the approach may continue; the crew must see the required visual reference by DH or go around.
Traps
- Averaging or taking the lowest of the three RVR values.
- Confusing DH (radio altimeter, precision) with MDH (barometric, non-precision).
- Believing the approach ban applies at any point after the FAF.
- Using CAT I circling minima for a CAT C aircraft.