Final answer:
The operational RVR limit for takeoff and other types of missions varies depending on several factors such as the type of aircraft, airport procedures, and regulations. Without RVR readout, pilots can use instrument flight rules (IFR) and onboard instruments to navigate and land in low visibility conditions.
Step-by-step explanation:
The operational RVR (Runway Visual Range) limit for takeoff depends on several factors such as the type of aircraft, the airport's operating procedures, and the local regulations. Generally, the RVR limit for takeoff is specified by the aircraft's performance capabilities and the airline's operational procedures. For example, a commercial jetliner might have a minimum takeoff RVR of 550 meters.
For all other types of missions, including landing, the RVR limit also varies depending on the aircraft, airport, and regulations. As a general guideline, most commercial aircraft require an RVR of at least 400 meters for landing.
If there is no RVR readout available, pilots can rely on other means of determining visibility, such as using instrument flight rules (IFR) procedures, which rely on onboard instruments to navigate and land in low visibility conditions.