Under FO restrictions for pilots with less than 100 hours, which visibility or RVR condition would trigger restrictions?

• A. Prevailing vis below 3/4 mile
• B. RVR below 4000 ft
• C. Either below 3/4 mile or below 4000 ft
• D. Neither below 3/4 mile nor below 4000 ft

Answer: (C)

Less-experienced pilots have stricter visibility protections, and the rule treats the two metrics—prevailing visibility and runway visual range—as separate gates. If either one falls below its threshold, a First Officer restriction applies. The thresholds are 3/4 of a mile for prevailing visibility or 4000 feet for RVR. This means that if the prevailing visibility drops under 3/4 mile, or the RVR drops under 4000 feet, the restriction must be used. If both measures stay above their thresholds, no restriction is triggered.

Prevailing visibility is how far you can see in general conditions, while RVR is the distance you can see along the runway from the instrument readings. Since either metric being too low can impact safe flight, the rule uses an OR condition: only one being below the limit is enough to require the restriction.