Part 135 or Part 91 — who answers for the flight.

Part 135 and Part 91 describe different operating frameworks under U.S. federal rules. Part 135 governs commuter and on-demand operations, including most charter; Part 91 sets general operating and flight rules for general aviation and for operations that don't fall under a Part 135 certificate.

The label isn't decided by the size of the jet or by who gets the invoice. The determining question is who holds operational control: who initiates, conducts, and terminates the flight, and who carries the operational responsibility under the applicable framework. The FAA has noted that sourcing the aircraft and the crew from the same provider is usually evidence of transportation for compensation that requires Part 135, not a way to convert the flight into Part 91.

What actually changes

On a Part 135 charter, the certificated direct air carrier needs active authority, and the aircraft has to be authorized in its operations specifications. The FAA keeps a searchable list to confirm both the operator and the aircraft cleared for charter; if the name or tail number doesn't appear, the official guidance is to check with the local Flight Standards office.

Part 135 also carries its own certification, training, manuals, maintenance, and operating requirements. The FAA notes that Part 135 maintenance can be more demanding than Part 91, and that the scope depends, among other factors, on the seating configuration and passenger count.

On certain Part 91 flights, the owner or entity that holds operational control carries the operating responsibility under the applicable program and rules. An invoice for "management," "dry lease," or "aircraft access" doesn't settle the classification on its own. The real structure of ownership, crew, control, and compensation has to be examined.

Who answers

Final legal liability depends on the facts, the contract, the jurisdiction, and the applicable law. It isn't accurate to promise a client that "the broker takes responsibility" or that "the owner always answers." A broker can carry duties of selection, disclosure, and contracting, but is normally not automatically the carrier or the operator exercising operational control.

The first line of diligence is identifying, in the contract, the direct air carrier, its certificate, the aircraft's operator, and the party exercising operational control. The FAA states that pilots conducting air transportation must be employed by or acting as agents of the certificate holder with operational control, or otherwise fall within the applicable certification framework.

The second is checking the insurance. Part 205 requires direct air carriers subject to the rule to maintain evidence of aircraft accident liability insurance and file it with the FAA; an aircraft shouldn't appear on the OpSpecs or operate under that framework without active coverage.

Questions for the gatekeeper

Before approving the flight, ask in writing:

• What's the legal name of the direct air carrier?
• What's their FAA certificate number, and which entity signs the transportation contract?
• Which tail number is authorized on the operator's OpSpecs?
• Who exercises operational control, and who selects the crew?
• Will the flight run under Part 135, Part 91K, or another authority — and why?
• What policy and limits apply to that operator and aircraft?

An answer that invokes "Part 91" to avoid naming the commercial operator deserves a pause. Part 91 can be correct in a genuine private structure, but it isn't a label available to disguise a charter. The test is the actual operation, not the commercial wording used to describe it.