Fractional ownership is the structure that lets a charter-shy executive own a real, registered interest in a business jet without running a flight department. NetJets, Flexjet, and the programs that followed all operate inside one specific corner of the regulations: 14 CFR Part 91 Subpart K — sections §91.1001 through §91.1443. It is neither the light-touch private-operation rule set of ordinary Part 91 nor the full commercial-carrier scheme of Part 135 charter. It is its own lane, with its own authorization document and its own recordkeeping section.
That middle position is exactly what makes Subpart K compliance confusing. Owners think they are flying "Part 91 private." Managers know they are carrying program-management obligations that look a lot like an air carrier's. And the FAA, in a surveillance review, expects to see a specific record set that proves the program qualifies as a fractional program, that operational control was correctly allocated for every flight, and that the aircraft were maintained under an approved inspection program.
This guide walks the whole structure: the six-element test that defines a fractional program, the FAA-issued management specifications that authorize it, the owner-versus-manager operational-control split, the §91.1027 recordkeeping requirements with their exact retention periods, and the maintenance scheme. Every regulatory claim below is cited to the specific section so you can verify it against the CFR.
What Part 91 Subpart K Actually Governs
Subpart K was added to Part 91 to give fractional programs a defined regulatory home. Before it existed, the FAA wrestled with whether a fractional owner sharing an aircraft was a private operator or was effectively buying air transportation. The answer the rule settled on: §91.1001(a) makes the subpart apply to both fractional owners and fractional ownership program managers, and builds an operational-control framework that allocates responsibility between them rather than forcing the program into the air-carrier box.
The vocabulary matters because it is definitional. §91.1001(b) defines each term, and a program either fits every definition or it does not qualify for Subpart K at all:
Fractional ownership program
A program of management services by a single program manager, on behalf of two or more owners, of two or more airworthy aircraft, with each program aircraft having at least one owner holding the minimum interest, a dry-lease aircraft exchange among owners, and multi-year program agreements.
Fractional owner
An individual or entity that possesses a minimum fractional ownership interest in a program aircraft and has entered into the applicable program agreements.
Program aircraft
An aircraft in which a fractional owner holds the minimum interest and that is included in the dry-lease aircraft exchange under the program agreements (plus manager-owned aircraft used to supplement program operations).
Program manager
The entity that offers fractional ownership program management services to fractional owners and is designated to fulfill the applicable Subpart K requirements.
Dry-lease aircraft exchange
A written arrangement under which the program aircraft are available, on an as-needed basis without crew, to each fractional owner.
"Operational control" is defined in §1.1 — not in Subpart K
Subpart K leans heavily on the concept of operational control, but it does not define the term itself. The definition lives in 14 CFR §1.1, which defines operational control, with respect to a flight, as the exercise of authority over initiating, conducting, or terminating a flight. Subpart K's §91.1011 and §91.1013 then build on that single §1.1 definition to allocate the responsibility between owner and manager. If you see a guide that cites operational control to a Part 110 or Part 119 section, it is wrong — the controlling definition is §1.1. This is the same definition that governs the operational-control question in Part 135.
The Six-Element Qualifying Test — and the 1/16 vs 1/32 Threshold
A structure only earns Subpart K treatment if it satisfies every element of the §91.1001(b) definition of a fractional ownership program. Miss one, and the operation defaults to a different rule — most often ordinary Part 91, or Part 135 if compensation for carriage is involved. The six elements:
| # | Required Element | What It Means in Practice |
|---|---|---|
| 1 | Single program manager | One entity provides the management services for the whole program. |
| 2 | Two or more airworthy aircraft | A single aircraft cannot constitute a fractional program. |
| 3 | At least one multi-owner aircraft | At least one program aircraft must have more than one owner. |
| 4 | Minimum fractional interest each | Each owner holds ≥1/16 (fixed-wing/powered-lift) or ≥1/32 (rotorcraft). |
| 5 | Dry-lease aircraft exchange | A written arrangement makes aircraft available without crew, as needed. |
| 6 | Multi-year program agreements | The program agreements run multi-year, not flight-by-flight. |
The interest threshold is a definitional gate, not a billing detail
Under §91.1001(b), the minimum fractional ownership interest is an interest equal to or greater than one-sixteenth (1/16) of a subsonic fixed-wing or powered-lift program aircraft, or one-thirty-second (1/32) of a rotorcraft. If an "owner" holds less than the applicable minimum, that person is not a fractional owner for Subpart K purposes, and an aircraft with no owner at or above the minimum is not a program aircraft. Programs that slice interests too thin to chase smaller buyers can inadvertently fall out of Subpart K — at which point the operation needs a different regulatory basis entirely.
Why this matters for records: the documents that prove each element — the program management agreement, the ownership interest schedule, the dry-lease exchange agreement, the multi-year term — are the foundation of the program's regulatory standing. In a surveillance review, the inspector will work from the management specifications down through these agreements to confirm the program still qualifies. Missing or expired versions of these documents are not a clerical problem; they go to whether the program is lawfully operating under Subpart K at all.
Management Specifications — the Program's Authorization Document
Just as a Part 135 operator runs off operations specifications, a Subpart K program runs off management specifications. Under §91.1014, the Administrator issues management specifications to the program manager on behalf of the fractional owners after finding, on investigation, that the applicant meets the applicable Subpart K requirements and is properly and adequately equipped to conduct safe operations. The management specifications are the master authorization the rest of the program is measured against.
What §91.1015 Management Specifications Contain
Per §91.1015, the management specifications set out the authorizations, limitations, and procedures under which the program operates, including:
- The procedures and authorizations under which program operations are conducted
- Approved inspection program reference under §91.1109
- Time limitations (or standards for determining them) for overhauls, inspections, and checks
- The principal base of operations and any required FAA contact information
- Any authorized deviations from, or exemptions to, the applicable rules
- Aircraft authorizations, limitations, and any business names used by the manager
Critically, the current management specifications are an explicit record the program manager must keep under §91.1027(a)(1). When an inspector arrives, the management specifications are typically the first document requested — and every downstream record (aircraft list, inspection program, operational-control acknowledgments) is checked for consistency against them. A program operating to a revision of its management specs that no longer matches its actual fleet or authorizations has a finding waiting to happen.
Operational Control — the Owner / Manager Split
Operational control is the single most distinctive feature of Subpart K, and the area where the records carry the most legal weight. The starting point is the §1.1 definition — authority over initiating, conducting, or terminating a flight — and Subpart K then allocates that authority and the responsibility that comes with it.
§91.1011 — Ultimate Responsibility, with Delegation
Under §91.1011, the fractional owner in operational control of a flight has the ultimate responsibility for safe operations. The owner may delegate performance of some or all of the associated tasks to the program manager — and that delegation is exactly how the model works in practice, since owners do not run dispatch. But the rule is explicit: when tasks are delegated, the owner and the program manager are jointly and individually responsible for compliance. Delegation moves the work, not the accountability.
§91.1013 — The Signed Operational-Control Acknowledgment
§91.1013 requires the program manager to brief each fractional owner on the owner's operational-control responsibilities, and to obtain a signed acknowledgment from the owner. The acknowledgment must define when the owner is in operational control and set out the owner's responsibilities and liabilities. The program manager must keep these acknowledgments available to the owners (or their representatives) and to the FAA. In practice this means a signed acknowledgment on file for every owner in the program — a record set that auditors specifically look for, and that lapses quietly as ownership rosters turn over.
Why the operational-control records are the litigation pressure point
Because operational control determines who is legally responsible for a flight, the operational-control acknowledgments and the per-flight allocation records are the first documents pulled after any incident or enforcement action — and the documents whose absence does the most damage. A program that cannot produce a signed §91.1013 acknowledgment for the owner on a given flight has a gap precisely where responsibility is being assigned. This is a documentation problem with direct liability consequences, which is why mature programs treat the acknowledgment file as a permanent, audit-ready record rather than a one-time onboarding formality.
§91.1027 Recordkeeping — Exactly What and Exactly How Long
14 CFR §91.1027 is the dedicated recordkeeping section for Subpart K. It tells the program manager what to keep at its principal base of operations (or another place approved by the Administrator) and — critically — sets the minimum retention periods. Get the retention periods right; they are a frequent source of error because they differ by record type.
| Record | CFR | Minimum Retention |
|---|---|---|
| Management specifications | §91.1027(a)(1) | Current (kept on file) |
| Current aircraft list (with equipage — e.g. RVSM, RNP) | §91.1027(a)(2) | At least 6 months |
| Individual pilot records | §91.1027(a)(3) | At least 12 months |
| Individual flight attendant records | §91.1027(a)(4) | At least 12 months |
The retention split most operators get backwards
Under §91.1027(b), the program manager must keep the current aircraft list required by §91.1027(a)(2) for at least 6 months, and the individual pilot and flight attendant records required by §91.1027(a)(3) and (a)(4) for at least 12 months. The crew records, not the aircraft list, carry the longer floor. These are minimums — and 12 months is rarely enough in practice for crew records, because pilot currency, recurrent training, and checking events span longer cycles and are routinely needed to defend the program in an audit. Treat §91.1027 as the floor, not the target. The detailed pilot-record content that goes into §91.1027(a)(3) closely parallels the pilot records the FAA requires of a Part 135 operator.
One more boundary worth drawing: §91.1027 is the operations-side recordkeeping rule. It is not the whole record set. Aircraft maintenance, alteration, and airworthiness records keep to their own Part 91 retention scheme under §91.417 — and the permanent records (total time in service, current inspection status, current AD compliance status, major alteration data) follow the same life-of-aircraft logic covered in our Part 91 aircraft records guide and airworthiness directive compliance records guide. A complete Subpart K record set is §91.1027 plus the §91.417 maintenance record chain — not one or the other.
Maintenance — the §91.1109 Inspection Program and the Optional CAMP
Maintenance under Subpart K has a baseline requirement and an optional, heavier framework on top of it. The distinction trips up operators who assume a fractional program automatically means a continuous airworthiness maintenance program. It does not.
§91.1109 — The Baseline Inspection Program (Required)
§91.1109 requires the program manager to establish an aircraft inspection program for each make and model of program aircraft and ensure each aircraft is inspected in accordance with that program. The written program must include the inspection instructions and procedures for the particular make and model, a schedule for performing the inspections (expressed in time in service, calendar time, number of system operations, or a combination), and the name and address of the person responsible for scheduling the inspections. A copy must be available to the person performing inspections and, on request, to the Administrator.
§91.1411 — CAMP Is Optional ("May"), Not Mandatory
This is the trap. §91.1411 says program aircraft may be maintained under a continuous airworthiness maintenance program (CAMP) under §§91.1413 through 91.1443 — permissive language, not a mandate. A manager that elects the CAMP route must then comply with the full §§91.1413–91.1443 scheme. A manager that does not elect CAMP still satisfies its maintenance obligation through the §91.1109 inspection program. Both paths are valid; the program's management specifications and inspection program documentation must make clear which one the program is on.
§91.1413 — If You Elect CAMP: DOM + Chief Inspector, Not the Same Person
Under §91.1413 ("CAMP: Responsibility for airworthiness"), a program manager operating under a CAMP is primarily responsible for the airworthiness of the program aircraft — airframes, engines, propellers, rotors, appliances, and parts — including performing maintenance and repairing defects between scheduled maintenance. The rule requires the manager to employ both a Director of Maintenance and a Chief Inspector, each a certificated mechanic with airframe and powerplant ratings, and it specifies that one person cannot hold both positions simultaneously. Any maintenance performed by another person must be done under the program manager's manual.
The records consequence is the same either way: every maintenance, preventive-maintenance, or alteration action produces an entry that must satisfy the §43.9 entry-content requirements (inspections are recorded under §43.11 — §43.9(c) expressly excludes them), and the resulting airworthiness records keep to the §91.409 / §91.417 inspection-and-retention scheme. Whether a fractional program runs a §91.1109 inspection program or a full CAMP, the document trail — entries, inspection status, AD compliance status — is what proves the fleet is airworthy.
Related Aviation Compliance Reading
The Subpart K Record Set an Inspector Expects to See
Pulling the sections together, here is the documentary spine of a defensible Subpart K program. None of these documents is optional, and each maps to a specific regulatory hook.
Management specifications
§91.1014 / §91.1015 / §91.1027(a)(1)Current FAA-issued authorization — the master document everything else is checked against.
Program & ownership agreements
§91.1001(b)Management agreement, ownership-interest schedule, dry-lease exchange, multi-year terms — proof the program qualifies.
Operational-control acknowledgments
§91.1013A signed acknowledgment on file for every owner, kept available to owners and the FAA.
Current aircraft list
§91.1027(a)(2)Fleet plus equipage (RVSM, RNP, etc.); retained at least 6 months.
Individual pilot records
§91.1027(a)(3)Certificates, ratings, experience, medical, testing, flight time, training dates; retained at least 12 months.
Individual flight attendant records
§91.1027(a)(4)Identity and training results; retained at least 12 months.
Inspection program (and/or CAMP)
§91.1109 / §91.1411–§91.1443Per make and model; if CAMP elected, DOM and Chief Inspector designations.
Aircraft maintenance & airworthiness records
§43.9 / §91.417Maintenance entries, inspection status, AD compliance status — the airworthiness proof chain.
Where Subpart K programs lose records — and FAA audits
The gaps are predictable and almost always documentary rather than operational:
- Operational-control acknowledgments that were signed at onboarding but never refreshed as the ownership roster turned over — leaving owners with no current §91.1013 acknowledgment on file.
- A management-specifications revision that no longer matches the actual fleet because aircraft were added or retired without the aircraft list being updated.
- Crew records discarded at the 12-month §91.1027 floor when training and checking history was still needed to demonstrate currency.
- An inspection-program document the manager cannot produce on request, or that does not cover a newly added make and model under §91.1109.
Every one of these is a tracking-and-retention failure, not a flying failure — which is exactly the category a compliance document layer is built to close. The same surveillance discipline that applies to a charter operator's binder applies here; see how to prepare for an FAA surveillance audit.
Keep the entire Subpart K record set audit-ready in one place
FileFlo is a compliance document intelligence platform — a read-only proof layer that classifies, indexes, and tracks the records a fractional program is required to keep. Upload your management specifications, operational-control acknowledgments, aircraft list, crew records, and inspection-program documents, and FileFlo:
- Classifies each document against the governing section (§91.1015, §91.1013, §91.1027, §91.1109)
- Tracks the §91.1027 retention floors (6 months / 12 months) and flags records approaching or past their minimum
- Surfaces missing operational-control acknowledgments as the ownership roster changes
- Generates an audit-ready record binder organized by CFR section for any FAA surveillance review
FileFlo sits alongside your program-management system and maintenance provider — it does not run the operation, allocate operational control, dispatch flights, or replace your inspection program or CAMP. It keeps the documents that prove your compliance audit-ready. Starter $89/mo · Professional $299/mo · 5-day free trial, no credit card required.
Frequently Asked Questions
What is Part 91 Subpart K and who does it apply to?
Part 91 Subpart K (14 CFR §§91.1001 through 91.1443) is the FAA rule set governing fractional ownership programs — the structure popularized by NetJets, Flexjet, and similar providers where multiple owners hold a fractional interest in one or more aircraft and share them through a managed program. Per §91.1001(a), the subpart applies to both "fractional owners" and "fractional ownership program managers." A qualifying program requires a single program manager providing management services, two or more airworthy aircraft, at least one aircraft with more than one owner, each owner holding at least a minimum fractional ownership interest, a dry-lease aircraft exchange arrangement documented in written agreements, and multi-year program agreements. If a structure does not meet every one of those elements, it is not a Subpart K program and a different operating rule (Part 91 Subpart F, Part 135, or Part 121) governs instead.
What is the minimum fractional ownership interest under §91.1001?
Under 14 CFR §91.1001(b), the minimum fractional ownership interest is an interest equal to or greater than one-sixteenth (1/16) of a subsonic, fixed-wing or powered-lift program aircraft, and one-thirty-second (1/32) of a rotorcraft program aircraft. An owner who holds less than the applicable minimum is not a "fractional owner" for purposes of Subpart K, and an aircraft in which no owner holds at least the minimum interest is not a "program aircraft." These thresholds are part of the definitional test that determines whether the program qualifies for Subpart K in the first place — they are not retention or interval rules.
How long must a Subpart K program manager keep records under §91.1027?
14 CFR §91.1027 sets several retention requirements, not just two. The current list of aircraft used or available for use in the program — including the operations each is equipped for, such as RVSM or RNP — must be kept for at least 6 months under §91.1027(a)(2) and (b). The individual pilot records and individual flight attendant records required by §91.1027(a)(3) and (a)(4) must be kept for at least 12 months. In addition, §91.1027(c)–(e) require a load manifest prepared in duplicate before each takeoff, a copy carried by the pilot in command, and the copies retained for at least 30 days at the principal operations base (or an FAA-approved location). The program manager must also keep its management specifications. Note that these are minimum retention floors specific to the Subpart K recordkeeping section — aircraft maintenance and airworthiness records keep to their own Part 91 retention rules under §91.417, and crew qualification, training, and testing records are frequently kept far longer than 12 months for currency-tracking and audit-defense purposes.
Is a continuous airworthiness maintenance program (CAMP) mandatory under Subpart K?
No. Under 14 CFR §91.1411, fractional ownership program aircraft "may" be maintained under a continuous airworthiness maintenance program (CAMP) under §§91.1413 through 91.1443 — it is permissive, not mandatory. The baseline maintenance requirement is §91.1109, which requires the program manager to establish an aircraft inspection program for each make and model of program aircraft and ensure each aircraft is inspected in accordance with that program. A manager that elects the CAMP route must then comply with the full CAMP scheme: §91.1413 makes the program manager primarily responsible for airworthiness, and requires both a Director of Maintenance and a Chief Inspector who, per the rule, cannot be the same person.
Who has operational control of a Subpart K flight — the owner or the program manager?
It depends on how operational control is allocated for the specific flight, and that allocation must be documented. Operational control itself is defined in 14 CFR §1.1 as the exercise of authority over initiating, conducting, or terminating a flight. Under §91.1011, the fractional owner in operational control of a flight has ultimate responsibility for safe operations, but may delegate performance of some or all of the associated tasks to the program manager — and when delegation occurs, the owner and the program manager are jointly and individually responsible for compliance. Section §91.1013 requires the program manager to brief each owner on the owner's operational control responsibilities and to obtain a signed acknowledgment defining when the owner is in operational control. Those signed acknowledgments are a core compliance record the program manager must keep available to owners and to the FAA.
What are management specifications and why do they matter for recordkeeping?
Management specifications ("management specs") are the FAA-issued authorization document for a fractional ownership program, analogous to operations specifications in Part 135. Under §91.1014, the Administrator issues management specifications to the program manager on behalf of the fractional owners after finding the applicant meets the applicable Subpart K requirements and is adequately equipped to conduct safe operations. Under §91.1015, the management specifications set out the authorizations, limitations, and procedures under which the program operates — including the approved inspection program reference, maintenance time limitations, weight-and-balance control, authorized deviations, and the principal base of operations. The current management specifications are an explicit §91.1027(a)(1) record the program manager must keep, and they function as the master authorization every other program record is measured against in an FAA review.
How is Subpart K different from Part 135 charter for recordkeeping?
Both are commercial-adjacent regimes with heavy documentation duties, but they answer different questions. Part 135 governs on-demand charter carriage of persons or property for compensation and runs off operations specifications, a §135.63 record-of-flight obligation, and detailed crew records under §135.63. Subpart K governs the fractional-ownership structure and runs off management specifications, the §91.1027 recordkeeping section, and a layered operational-control allocation between owner and manager that has no Part 135 equivalent. An operator that flies the same aircraft under both a fractional program and Part 135 charter must keep both record sets and be able to demonstrate, for any given flight, which regime and which operational-control framework applied. The practical recordkeeping burden is comparable; the document taxonomy is not interchangeable.
Related Aviation Compliance Guides
What Records Must a Part 135 Operator Keep?
The full charter recordkeeping obligation — the closest commercial analog to Subpart K records
What Is Operational Control in Part 135?
The §1.1 operational-control definition that Subpart K §91.1011 and §91.1013 build on
Part 135 Pilot Records Required by the FAA
The pilot-record content that parallels §91.1027(a)(3) individual pilot records
Part 91 Aircraft Records Requirements
The §91.417 maintenance and airworthiness record chain that completes the Subpart K record set
Part 91.409 Inspection Requirements
How inspection regimes and §91.417 retention interact with the §91.1109 program
Preparing for an FAA Surveillance Audit
The surveillance-readiness discipline that applies equally to a fractional program
Prove your fractional program is audit-ready — before the FAA asks
FileFlo classifies your Subpart K records against §91.1015, §91.1013, §91.1027, and §91.1109, tracks the 6-month and 12-month retention floors, and assembles an audit-ready record binder organized by CFR section. Keep management specs, operational-control acknowledgments, the aircraft list, and crew records current and provable — all in one compliance record set.
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