Low Visibility Approach Minima

What is Low Visibility Approach Minima?

Low visibility approach minima set the minimum RVR and DH values for safe approach and landing when visibility is reduced, such as in fog, heavy rain, or snow. For precision approaches, especially Category II (CAT II) and Category III (CAT III), these minima allow operations in conditions where standard visual cues are unavailable or severely restricted.

Categories and Minima

• CAT I: DH not lower than 200 ft and RVR not less than 550 m
• CAT II: DH lower than 200 ft but not lower than 100 ft, RVR not less than 300 m
• CAT IIIA: DH lower than 100 ft or no DH, RVR not less than 200 m
• CAT IIIB: No DH or DH lower than 50 ft, RVR not less than 75 m
• CAT IIIC: No DH and no RVR limitation (not currently in operational use)

Operational Requirements

• The aerodrome, aircraft, and crew must all be specifically approved for low visibility operations.
• The operator’s procedures must ensure all required equipment is serviceable and that LVPs (Low Visibility Procedures) are active at the aerodrome.
• The pilot-in-command must verify all operational criteria, including crew qualifications, equipment status, and aerodrome readiness, before commencing a low visibility approach.
• Height callouts below 200 ft must use the radio altimeter, and at least one pilot must continuously monitor instruments until landing is complete.

Aerodrome and Crew Considerations

• Only aerodromes with approved low visibility procedures may be used for CAT II/III approaches.
• Crew must be simulator-trained and checked for the specific operation and aircraft type.
• Any changes in ground or airborne equipment status can affect the applicable minima and may require reverting to higher minima or discontinuing the approach.

Key Procedures

• If RVR drops below minima before 1000 ft above the aerodrome, the approach must not be continued beyond that point.
• If RVR drops below minima after passing 1000 ft, the approach may continue to DA/H or MDA/H, but landing may only occur if required visual references are obtained at or above minima.
• The minimum required visual references must be clearly defined and known to the crew.

Take-off Minima

• Take-off minima are also expressed as visibility or RVR, with specific requirements for low visibility take-offs (LVTO) below 400 m RVR, requiring special operator approval and procedures.