What is the limitation for taking off at an airport with a single functioning RVR transmissometer reporting 700 RVR?

The correct response is based on understanding the regulations surrounding runway visual range (RVR) and the associated weather minimums for takeoff. When an airport has a single RVR transmissometer reading 700 feet, this does not meet the minimum requirements for a standard departure in most commercial aviation operations.

In many regulatory frameworks, such as those from the FAA, the minimum required RVR for takeoff can typically range around 1,600 RVR, depending on the aircraft type and approach procedure. When the RVR is reported below the required threshold, such as 700 RVR, it indicates a significant limitation on visibility which may prevent safe takeoff conditions.

Regulations are stringent for takeoff to ensure the safety of the flight and passengers. A reading of 700 RVR indicates that visibility is too low to ensure pilots can see the runway environment and other necessary visual cues for a safe departure. In instances of low visibility, additional visual references or improving weather do not suffice to compensate for the lack of adequate RVR, which is a critical factor in takeoff safety.

Therefore, under these conditions, taking off would not be permitted, highlighting the significance of the RVR readings in ensuring safe aviation operations.