Can you take off with an RVR of M/6/6?

The answer to the question about whether you can take off with an RVR of M/6/6 is based on regulatory requirements and operational safety considerations regarding Runway Visual Range (RVR).

When the RVR is reported as M/6/6, it indicates that the visibility due to atmospheric conditions is minimal (denoted by "M"), which refers to a less than minimum value, while the numbers "6/6" represent the operational capability of the sensors. For most commercial aviation regulations, particularly those governed by entities such as the FAA or EASA, the requirement states that a minimum of two operational RVR sensors is typically needed to proceed with takeoff in low visibility conditions.

Having at least two operational sensors allows for cross-checking and verification of the runway visibility; this redundancy is crucial in ensuring that pilots can make informed decisions about safety when departing in reduced visibility conditions. If only one sensor is operational, it does not provide adequate confirmation as required by typical regulations, and the visibility may not be reliable enough, which is why exceeding those limits, regardless of how many sensors are operational, may not be permissible.

Thus, the requirement for at least two operational sensors ensures that there is enough information to assess the actual runway conditions definitively