What Is FAR Part 91K?
Part 91 Subpart K (91K) governs fractional ownership programs — the regulatory framework that allows multiple owners to share an aircraft while maintaining the operational flexibility of Part 91. If you're interviewing with NetJets, Flexjet, Wheels Up, or any fractional operator, expect 91K questions. These aren't softballs. Interviewers use them to separate candidates who understand the nuanced middle ground between Part 91 and Part 135.
The core distinction: fractional operations look like charter to the uninformed, but they operate under a fundamentally different legal structure. Each owner holds a minimum 1/16 interest in a specific make and model, and the managing company provides crew, maintenance, and flight scheduling. Knowing where 91K departs from standard Part 91 — and where it borrows from 135 — is exactly what interviewers probe.
Key 91K Rules You Must Know Cold
Operational Control
Under 91K, operational control shifts depending on who is flying. When an owner flies on their own aircraft, it's straightforward Part 91K. When an owner flies on a different program aircraft (an interchange or dry-lease exchange), the managing company holds operational control. Interviewers frequently ask candidates to define operational control and identify who holds it in specific scenarios — get this wrong and you signal a fundamental misunderstanding of the operation.
Flight and Duty Limitations
Part 91K requires fractional operators to have an Approved Program for flight, duty, and rest. These are not the Part 135 limitations verbatim — they can differ, but the FAA must approve them. The program document governs your rest requirements, not the generic 135.267 framework. Know that 91K mandates FDP and rest rules exist, but the specifics live in each operator's approved program. This is a common interview trap: candidates cite 135 limits when the correct answer is "per the operator's FAA-approved program."
Pilot Training Requirements
Fractional crews must comply with Part 91K training requirements, which include initial, recurrent, and differences training. Critically, 91K requires crewmembers to meet the ATP certificate standard for operations in aircraft requiring a type rating — aligning fractional operations closer to air carrier standards than standard Part 91 piston flying.
"You're a NetJets pilot flying an owner on a different aircraft than the one they hold an interest in. Who has operational control, and what regulations apply?" — The answer: the fractional program manager holds operational control; Part 91K applies. If the FAA determines it resembles common carriage, Part 135 could apply instead. Knowing the boundary matters.
Aircraft Airworthiness and Maintenance
Fractional aircraft must be maintained under a continuous airworthiness maintenance program (CAMP), similar to the Part 135 requirement. MEL applicability, inspection programs, and airworthiness directives all fall under this structure. If you're coming from a Part 121 background, the CAMP concept is familiar — but knowing it applies in 91K specifically demonstrates regulatory depth.
Where Candidates Get Tripped Up
The most common mistake is conflating 91K with either pure Part 91 or Part 135. Fractional is neither. It occupies its own regulatory space with specific carve-outs and requirements. A few critical distinctions interviewers exploit:
- Compensation is allowed — Owners pay for flight hours, but this doesn't make it charter. The ownership interest is the legal distinction.
- Drug and alcohol testing applies — 91K operators are subject to DOT drug and alcohol testing programs, unlike standard Part 91 operators.
- Weather minimums — Fractional operations must apply instrument approach minimums no lower than Part 135 IFR minimums, not the more permissive Part 91 personal minimums.
- Passenger briefings — Required, similar in scope to Part 135 requirements.
FAR 91.1069 through 91.1087 cover the flight and duty time requirements under Subpart K. 91.1411 through 91.1443 cover the CAMP requirements. Cite the specific subparts in your interview — it signals genuine regulatory familiarity, not surface-level study.
How to Prepare for 91K Interview Questions
Reading the FARs is the baseline. What separates prepared candidates is being able to apply 91K rules to realistic operational scenarios under interview pressure — explaining the logic, not just the rule number. Interviewers at NetJets and Flexjet consistently report that candidates who struggle with 91K questions also tend to struggle with crew resource management and operational judgment scenarios. Regulatory knowledge signals how you'll handle ambiguity in the flight deck.
Build your prep around scenario-based questions, not rote memorization. Practice articulating why a rule exists alongside what the rule says. The 91K study guide on Vectors to Hired breaks down Subpart K into operator-specific scenarios drawn from real pilot interviews, with AI Voice Coach feedback to sharpen your verbal delivery before you're in the room.
Regulatory depth is a differentiator at fractional operators. Invest the time to own it.