Regulation · guide
Part 91 vs Part 135: How US Private and Charter Flight Rules Differ
Compare US Part 91 and Part 135 operations, including charter authority, crews, maintenance, operational control and the checks passengers should make.
In US aviation, Part 91 contains general operating and flight rules, while Part 135 adds requirements for the commuter and on-demand operations within its scope. A typical corporate flight carrying its owner’s business team and a typical charter carrying a paying customer may use similar aircraft, but their operating arrangements and responsibilities are different.
The distinction concerns the flight being conducted. It is not a permanent badge attached to an aircraft’s cabin, its owner or the pilot’s uniform. The same jet can be used for an owner trip and, under the correct authority and arrangements, a separate charter trip.
For passengers, the practical question is straightforward: who is authorised to provide this particular transportation? Answering it requires more than seeing an aircraft registration or a commercial pilot certificate.
What Part 91 and Part 135 actually cover
Part 91 supplies general rules covering issues such as flight conduct, aircraft operation and maintenance responsibilities. It applies broadly, with specific provisions and exceptions depending on the operation.
Part 135 covers the commuter and on-demand operations identified in its applicability provisions. Many business jet charters fall within this framework, but it should not be described as the rulebook for every commercial aviation activity. Other operations can fall under Part 121 or other applicable provisions.
The two parts are also not entirely separate systems. A Part 135 operator follows applicable general rules alongside the additional requirements governing its commercial operation. The authorisation to act as an air carrier or commercial operator comes through the certification framework, including Part 119, and the appropriate operating authority and specifications.
That is why “Part 91 versus Part 135” is useful shorthand, but only if the explanation does not remove the other rules that make the arrangement lawful.
When does a flight need charter authority?
Ordinary on-demand charter involves an operator supplying air transportation to a customer for compensation. The operator needs the authority appropriate to that operation, including the applicable safety and economic authority.
However, compensation is not a one-word test that resolves every aviation arrangement. US rules contain narrowly defined exceptions and specific arrangements that permit certain payments or reimbursements without treating the operation as ordinary charter.
For example, Part 91 Subpart F addresses particular time-sharing, interchange and joint-ownership arrangements for the aircraft and operations within its scope. The conditions and permitted charges matter. These arrangements are not an invitation to sell normal charter flights using different wording on the invoice.
Equally, paying a pilot is different from selling air transportation. A corporation can employ qualified pilots to operate its aircraft for its own legitimate business use. The fact that those pilots receive salaries does not automatically make every company flight a charter.
The difficulty arises when an arrangement is presented as private operation while someone is, in substance, supplying aircraft and crew as transportation. The FAA’s guidance for pilots, owners and operators emphasises examining the actual operating and leasing arrangement, rather than relying on the paperwork’s label.
How pilot qualifications and checking differ
Pilot requirements depend on aircraft, role and operation. A private pilot certificate is not a charter business licence, and a commercial pilot certificate does not independently authorise its holder to sell any air transportation they wish.
The relevant pilot must have the certificates, ratings, medical eligibility, experience and current qualifications required for the assigned duties. For a business jet, this can include a type rating and other aircraft-specific qualifications, with additional requirements depending on whether the pilot serves as captain or second in command.
Part 135 adds operator-related qualification and checking obligations. Section 135.293, for example, establishes initial and recurrent pilot testing requirements. Other sections address instrument checks, line checks and training as applicable.
It would still be wrong to imply that a professional Part 91 flight department operates without training or checking. Corporate operators may use substantial recurrent simulator training, standard operating procedures and internal requirements that go beyond legal minimums. A comparison should distinguish the regulatory baseline from a particular operator’s actual standards.
For readers considering the profession, the route into corporate piloting therefore needs to separate certification requirements from employer and insurer expectations.
Flight time, rest and schedule flexibility
A charter schedule has to fit the applicable crew flight-time and rest requirements, not simply the passenger’s preferred itinerary. A late meeting or an extra stop can change the feasibility of the remaining trip.
Part 135 contains specific limitations and rest provisions whose application depends on the kind of operation and crew arrangement. Reducing those provisions to one universal “maximum duty day” can mislead passengers and schedulers.
Non-fractional corporate Part 91 operations do not simply inherit the same Part 135 limits. Nevertheless, fatigue remains an operational risk. A responsible flight department still needs a workable fatigue policy, appropriate staffing and the ability to decline an unsafe schedule.
In practical terms, “private” does not mean unlimited flexibility. Aircraft performance, maintenance, airport access, weather and human fatigue continue to shape the trip even when the precise commercial rule does not apply.
Maintenance obligations apply to both
Both private and charter aircraft need to meet the requirements applicable to their airworthiness, inspections and maintenance. Part 91 operation does not mean that the owner can choose whether to comply with safety-critical requirements.
Part 135 adds maintenance-related requirements, with important differences according to the aircraft and operation. The applicable programme cannot be summarised accurately by saying that every charter jet receives one identical inspection package.
For an owner, the useful comparison is the actual maintenance programme, records, responsible organisations and oversight arrangements. For a charter passenger, the operator’s authority and aircraft authorisation are essential checks; a recent cabin refurbishment or an impressive exterior photograph proves neither.
Aircraft age is also an incomplete shortcut. Condition, maintenance history, compliance and operational suitability require proper evidence. A newer aircraft does not eliminate the need to verify the company operating it.
Operational control is the central responsibility
Operational control concerns responsibility and authority over initiating, conducting and terminating the flight. It is broader than choosing the catering or approving a departure time.
For Part 135 operations, Section 135.77 places responsibility for operational control with the certificate holder. The operator’s authorised personnel and pilot in command carry out their respective responsibilities within that structure.
A passenger does not take over those obligations by asking to leave earlier, selecting a destination or paying for the aircraft. Commercial coordination and operational authority are different functions, which is also important when a broker arranges the trip.
Why a lease needs careful reading
Under a genuine dry lease, an aircraft is supplied without crew and the lessee assumes the relevant operating responsibilities in the actual arrangement. A passenger unexpectedly asked to sign a document accepting operational control should understand what that means before proceeding.
Consider a fictional booking in which one seller chooses the aircraft, supplies the pilots, controls the schedule and charges the customer for transportation, but asks the customer to sign a “dry lease” immediately before boarding. The name of that document does not by itself establish a lawful private operation.
The FAA’s passenger guidance on chartering identifies attempted transfers of operational control and coaching passengers about what to tell inspectors as warning signs. A legitimate specialist can explain the arrangement clearly instead of treating questions as an inconvenience.
Where does fractional Part 91K fit?
Qualifying US fractional ownership programmes operate within a dedicated framework under Part 91 Subpart K. These programmes have management specifications and their own requirements; they should not be equated with an ordinary owner-operated Part 91 flight.
The FAA’s fractional programme guidance provides the regulatory starting point. A share purchase also involves contracts that determine access, charges and other rights, explored in what fractional aircraft owners actually own.
This is another reason to ask about the specific operation. The phrases “private jet,” “fractional” and “charter” describe different elements of a travel purchase and should not replace the relevant legal analysis.
A practical comparison
| Question | Typical corporate Part 91 operation | Typical Part 135 charter operation |
|---|---|---|
| Why is the aircraft flying? | Owner or company purposes under a legitimate private operating arrangement | Covered on-demand transportation supplied to customers |
| Who needs operating authority? | The actual arrangement determines the applicable requirements; Part 91 alone is not charter authority | The authorised certificate holder conducts the operation under applicable specifications |
| Who supplies crew standards? | Applicable rules plus employer, insurer and flight-department requirements | Applicable rules plus operator training, qualification and checking requirements |
| What should passengers verify? | Purpose and responsibilities of the arrangement, particularly if leasing | Actual operator, appropriate authority and aircraft authorisation |
The table describes common business aviation situations. Exceptions, other operating parts and jurisdiction-specific economic requirements still need to be considered for an actual flight.
What to check before paying for a US charter
Ask for the legal identity of the direct operator and confirmation that the proposed aircraft is authorised for the flight. Understand whether the company taking your payment is that operator, a broker or another contracting party.
Check insurance and any independent audit claims separately. They can add useful evidence, but an audit logo cannot replace operating authority. If the aircraft or operator changes, obtain updated details rather than assuming the original checks automatically cover the substitute.
Most importantly, do not accept an unexplained transfer of legal responsibility as a routine boarding form. The certificate and its associated approvals should help identify who is providing the operation and on what authority.
Frequently asked questions
Can a Part 91 aircraft ever carry paying passengers?
Specific arrangements can permit certain payments or reimbursements under limited conditions. That does not authorise ordinary charter sales. The exact aircraft, purpose, payment and operating arrangement need to fit the applicable rules.
Can a corporate pilot be paid under Part 91?
Yes, a qualified professional pilot can be employed for legitimate private operations. Paying for pilot services and selling air transportation are different questions. The pilot must still meet the requirements for the aircraft and duties.
Is Part 135 an aircraft ownership category?
No. It concerns covered operations. A charter operator may manage an aircraft owned by someone else, and an aircraft may conduct separate owner and authorised charter flights under suitable arrangements.
Does a commercial pilot certificate permit selling charter?
No. Pilot certification is only part of the requirement. The transportation must also be conducted under the appropriate operating authority and rules. A qualified pilot cannot make an unauthorised charter lawful simply by taking the controls.
