What is the lowest visibility requirement for takeoff under part 91?

Under Part 91 of the Federal Aviation Regulations, there are indeed no specific visibility restrictions for takeoff in visual flight rules (VFR) conditions. This means that pilots operating under Part 91 can take off in conditions where visibility may be less than what is typically required for other operations, as long as they can maintain adequate visual reference to the runway environment and are capable of safely proceeding with the flight.

It’s essential to note that while Part 91 doesn't impose visibility limits, pilots must still adhere to any additional restrictions imposed by the operators or local regulations, which may include minimum visibility requirements set by specific airports or special requirements for certain types of operations. This flexibility allows pilots to assess the situation leading up to the takeoff and make decisions based on actual conditions and their personal comfort with flying in those conditions.