Part 91
Part 91 is the section of the US Federal Aviation Regulations covering private, non-commercial flying. An owner flying their own jet, a company flying its executives, or a fractional programme operating under Subpart K all fly under Part 91. Its rules are lighter than the commercial rules: no operating certificate, less prescriptive crew rest and training requirements, and more freedom over airports and weather minimums. Crucially, Part 91 flights cannot be sold to the public; if money changes hands for carriage, the flight generally must be Part 135. Many countries mirror the split, with a private category for owners and a commercial category requiring an air operator certificate.