Short answer
Part 91 is the FAA's general rulebook for flying, including private, non-commercial flights. Part 135 is the stricter set of rules for on-demand commercial flights, such as charters. If you pay for a flight in the US, it must be operated by a company holding a Part 135 certificate, which requires more pilot training and checking, duty and rest limits, stricter maintenance and drug and alcohol testing. A paid flight operated under Part 91 is an illegal charter.
“Part 91” and “Part 135” are sections of the US Federal Aviation Regulations. They sound technical, but the difference affects every charter passenger.
Part 91: The General Rules
Part 91 contains the basic operating rules for all aircraft in the US. On its own, it covers private, non-commercial flying: an owner flying their own aircraft, or a company flying its employees on its own jet. There are no required duty-time limits for pilots and fewer requirements for training and maintenance programs.
Part 135: The Rules for Charter
Part 135 covers on-demand commercial flights, where passengers pay for transportation. To fly charters, a company must hold a Part 135 certificate from the FAA. Compared with Part 91, Part 135 adds:
- Pilot requirements and regular check rides with FAA-approved training programs
- Flight time, duty and rest limits for crews
- Approved maintenance programs for each aircraft
- Stricter weather minimums for takeoff and landing
- Drug and alcohol testing for crews and safety staff
- FAA oversight of the company, its aircraft and its managers
Outside the US, charter operators hold their country’s equivalent certificate.
Illegal Charter: The Risk to Avoid
An illegal charter is a paid flight flown under Part 91 by someone without a Part 135 certificate. It might be cheaper, but the FAA warns that these flights may not meet commercial safety standards, and passengers may not be protected by the operator’s insurance. Warning signs include an unusually low price, vague answers about who the operator is, and being asked to call it a “shared cost” or “leased” flight.
Brokers and Operators
A broker, like Air1 Jets, arranges flights but does not operate aircraft. US rules require brokers to say they are not the air carrier and to tell you which operator will fly you. Read why use a charter broker.
How to Check Your Flight
- Ask for the operator’s name and Part 135 certificate number.
- Ask for the aircraft’s tail number, and check that it is on the operator’s certificate.
- Ask about independent audits such as ARGUS, Wyvern or IS-BAO.
Every flight we arrange is operated by an FAA Part 135 operator, or the local equivalent abroad, and must pass Air1 Clearance.
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