Part 91 vs Part 135: What Owners Actually Need to Know
Part 91 covers private, non-commercial flying: you own the aircraft and you cannot charge others to fly on it. Part 135 is the FAA certificate that permits on-demand commercial charter, meaning you can sell seats or whole-aircraft trips. The distinction determines who can pay for a flight, what maintenance and crew rules apply, and how much oversight the FAA applies to the operation.
Most owners meet this distinction the day they ask whether the aircraft can pay for itself. The answer sits entirely in which set of rules the flight runs under.
What Part 91 actually covers
Part 91 is the general operating rulebook. Private flying, corporate flight departments, an owner moving their own people. No one on board is paying for transportation.
The tradeoff is flexibility for revenue. Under Part 91 you set your own schedule, you are not bound to commercial crew duty limits, and the maintenance program is less demanding. You also cannot legally sell a single seat.
What Part 135 adds
Part 135 is a certificate, not just a rule set. An operator applies for it, proves out manuals, training programs, maintenance procedures and management personnel, and gets audited on all of it.
In return the operator can sell transportation. That is the entire point.
What comes with it:
- Stricter crew duty and rest limits
- A continuous airworthiness maintenance program
- Drug and alcohol testing programs
- Operational control that stays with the certificate holder, not the owner
That last one is where owners are most often surprised.
Where owners get it wrong
The common error is assuming that placing an aircraft on a management company’s Part 135 certificate means the owner still calls every shot. It does not. When a trip runs as a charter, operational control belongs to the certificate holder. They decide whether the flight goes.
The second error is treating charter revenue as a way to make the aircraft free. It offsets fixed cost. It rarely covers it, and it adds cycles, wear and scheduling friction. Run the numbers on the specific tail before assuming.
The practical decision
If the aircraft exists to move you and your people, Part 91 is simpler and cheaper. If you want third-party revenue, you need Part 135, which in practice means a management company unless your operation is large enough to justify its own certificate.
Neither answer is better. They solve different problems.
Common questions
Can I charter out my own aircraft under Part 91?
No. Charging passengers for transportation is commercial operation and requires a Part 135 certificate, either your own or through a management company that places your aircraft on its certificate.
Is Part 135 more expensive to operate under?
Generally yes. Part 135 carries stricter crew duty limits, maintenance programs, and record-keeping. Those requirements add cost, which is why many owners place their aircraft with a management company rather than obtaining a certificate directly.
What is the difference between Part 135 and Part 121?
Part 121 governs scheduled airline service. Part 135 governs on-demand and commuter operations. Business jet charter falls under Part 135.