What Is Part 135 in Aviation? (Clear Guide for Charter and Air Taxi Operations)

If you’ve ever booked a charter flight or considered chartering out your aircraft, you’ve likely encountered references to Part 135. Understanding this regulation is essential for anyone involved in commercial aviation outside the major airlines.

Key Takeaways

• FAA Part 135 is the U.S. regulation governing commuter and on-demand operations—including charter flights, air taxis, air ambulances, and small cargo services—using aircraft with 30 or fewer seats or up to 7,500 lb payload.
• Part 135 sits between the flexible Part 91 (private flying) and the very strict Part 121 (major airlines), imposing higher safety standards, rigorous maintenance requirements, and stricter pilot qualifications than non-commercial operations.
• Operating under Part 135 requires an FAA air carrier certificate, operations specifications, and ongoing regulatory oversight, with the certification process typically taking 6–12 months.
• For passengers and aircraft owners, Part 135 directly affects safety protocols, pricing, operational flexibility, and legal liability in the event of an accident.
• RESQ specializes in aviation accident and injury cases under all FAR parts, including Part 135, helping injured passengers and families understand their legal rights.

What Is FAA Part 135? (Straight Answer First)

14 CFR Part 135 is the section of federal aviation regulations governing “commuter and on-demand operations.” This includes charter jets, turboprops, helicopters, air taxis, air ambulances, and small cargo operators conducting commercial operations for compensation or hire.

The regulation applies to aircraft with 30 or fewer passenger seats and a maximum payload capacity of 7,500 pounds or less. Larger aircraft and scheduled airline fleets fall under Part 121 instead.

“On-demand” means flights operate when requested by a customer rather than on fixed schedules. However, limited commuter operations (5+ round trips per week on defined routes) can still fall under Part 135 if aircraft size remains below thresholds.

Many business jets and helicopters switch between Part 91 for non-revenue repositioning and Part 135 for revenue flights. Whenever compensation or hire is involved, Part 135 rules must be fully followed.

The Federal Aviation Administration enforces Part 135 as part of Title 14 of the Code of Federal Regulations, forming a core legal framework for U.S. commercial charter aviation.

How Part 135 Fits into the FAA Regulatory System

Parts 91, 121, and 135 are the three main operational rule sets pilots and operators deal with in U.S. civil aviation. Understanding where each applies helps clarify the regulatory landscape.

Part 91 covers general aviation operations and non-commercial flights. Part 121 covers large scheduled carriers like Delta, American, UPS, and FedEx. Part 135 covers smaller charter, commuter operators, and air taxi services.

Part 119 serves as the certification gateway, determining who must operate under which part based on “common carriage”—carrying persons or property for compensation while holding out services to the public.

Safety requirements, oversight, and compliance costs generally increase moving from Part 91 to Part 135 to Part 121, while day-to-day operational flexibility typically decreases in that same progression.

Even under Part 135 and Part 121, the basic general operating rules and flight rules of Part 91 still apply unless more restrictive regulations override them.

Part 135 vs. Part 91 vs. Part 121 (High-Level Comparison)

Many owners, pilots, and paying passengers want to understand how Part 135 compares to private flying under Part 91 and airline operations under Part 121.

FAR Part	Typical Use	Aircraft Size	Schedule Type	Crew/Oversight	Example Operators
Part 91	Private/corporate	Any size	On-demand/private	PIC authority, minimal oversight	Corporate jets, private owners
Part 135	Charter/air taxi/air ambulance	≤30 seats, ≤7,500 lb payload	On-demand, limited schedule	1-2 pilots, POI oversight, annual audits	Charter companies, medevac
Part 121	Scheduled airlines/cargo	>30 seats or >7,500 lb	Fixed schedules	Two pilots + flight dispatcher, intense oversight	Delta, FedEx, United

Part 91 applies to non-commercial operations like a company flying its own corporate jets for internal travel. This offers significant flexibility in weather minimums, runway requirements, and rest requirements.

Part 121 represents the “gold standard” for scheduled air carriers with larger aircraft, requiring two pilots, dispatchers, and formal safety management systems.

Part 135 occupies the commercial middle ground: commercial operations with smaller aircraft and on-demand or commuter flights, with safety standards more stringent than Part 91 but slightly less rigid than Part 121.

Certification to Operate Under Part 135

No operator can simply decide to fly under Part 135. Obtaining an FAA air carrier certificate and ops specs requires a structured, multi-phase approval process.

The certification process typically includes five phases:

1. Pre-application and manuals submission
2. Formal application
3. Document compliance review
4. Demonstration/proving flights and inspections
5. Final certification

This commonly takes 6–12 months and can cost over $500,000 for complex applicants due to consultant fees and FAA backlogs.

Applicants must submit a General Operations Manual, Training Program, Maintenance Program, and proof of financial and managerial capability.

The FAA assigns a Principal Operations Inspector (POI) and often a Principal Maintenance Inspector (PMI) to oversee ongoing compliance, conduct regular inspections, and approve operational changes.

Certification defines geographic operations area, approved airports, aircraft types, and whether the carrier can conduct VFR/IFR operations, including special authorizations like CAT II or CAT III approaches.

Key Management Roles Required

Part 135 operators must designate key management personnel accepted by the FAA:

• Accountable Executive: Overall responsibility for safety and compliance
• Director of Operations/Operations Manager: Day-to-day flight operations and regulatory compliance
• Chief Pilot: Pilot standards, specific training, and checking
• Director of Maintenance/Maintenance Manager: Airworthiness and maintenance standards

The FAA evaluates each nominee’s experience, typically requiring 3–5 years of relevant Part 135 or Part 121 experience. Small single-pilot operations may combine roles if the FAA approves.

Pilot Qualifications and Crew Requirements Under Part 135

Part 135 demands higher pilot qualifications and training standards than private operations, often approaching airline-level rigor for complex aircraft.

The pilot in command in turbine-powered Part 135 operations typically must hold an Airline Transport Pilot certificate, meet minimum total flight time (1,200 hours), and pass regular proficiency checks every 6–12 months.

Second in command requirements vary by aircraft type and ops specs. Some smaller aircraft allow single-pilot operations, while larger jets require a qualified flight crew of two pilots.

Recurrent training covers normal, abnormal, and emergency operational procedures in simulators or actual aircraft, plus company-specific protocols.

Part 135 mandates drug and alcohol testing programs, crew rest requirements, and operational control systems like flight following that exceed Part 91 expectations.

Crew Duty, Rest, and Flight Time Limits

Typical Part 135 duty and rest requirements include:

• Maximum 8 hours flight time per 24-hour period
• Maximum 10 hours duty time
• Minimum 10 consecutive hours off-duty
• Maximum 30 flight hours per 7 days
• Maximum 100 flight hours per 30 days

These limits manage fatigue risk and are more stringent than Part 91’s vague “fit for duty” standard, though generally less complex than Part 121 rules.

Exceeding duty limits has been a factor in NTSB-investigated accidents and can affect liability in subsequent legal claims.

Aircraft Maintenance and Safety Standards in Part 135

Part 135 imposes structured, recurring inspection and maintenance obligations that exceed typical Part 91 requirements.

Aircraft must be enrolled in approved inspection programs—100-hour inspections, manufacturer-based programs, or continuous airworthiness maintenance programs for larger fleets. All maintenance must be performed by appropriately certificated personnel or Part 145 repair stations.

Detailed maintenance records documenting airworthiness directives compliance, component life limits, and regular inspections are mandatory. Missing or falsified records constitute serious violations—the FAA grounded a Part 135 operator in 2019 for falsified maintenance logs.

Many Part 135 operators adopt voluntary safety management systems and modern safety tools like FOQA and FDM data analytics. SMS mandates are expanding to operators with 10+ aircraft by 2026.

These rigorous maintenance requirements directly affect cost: charter flights under Part 135 are typically 20–50% more expensive than comparable Part 91 flights.

Operational Safety and Weather/Runway Limits

Part 135 imposes stricter weather minimums for departures and approaches than Part 91:

• Higher visibility requirements for IFR takeoffs (1 statute mile minimum)
• Defined takeoff minimums and alternate airport requirements
• Conservative landing distances calculations (60-115% of calculated distance)
• Prohibition on zero-visibility takeoffs

These regulations ensure safety across varying conditions and contribute significantly to lower accident rates. NTSB data shows Part 135 at approximately 1.2 accidents per 100,000 flight hours compared to Part 91’s 5.5.

Types of Operations Covered by Part 135

Part 135 covers diverse commercial services. Recognizing them helps passengers understand when they’re on a Part 135 flight.

Major categories include:

• On-demand passenger charters (business jets, turboprops)
• Commuter operations on fixed routes with smaller aircraft
• Air taxi services on short regional legs
• Air ambulance/medical flights
• Cargo operations using light aircraft (under 7,500 lb payload)

For example, a 9-seat turboprop flying daily commuter flights between smaller cities operates under Part 135, as does a helicopter company providing on-demand trips to offshore oil platforms.

While many passengers think of “private jet” travel as unregulated, flights sold to the public should be conducted under a valid Part 135 certificate. Gray-market charter—aircraft operating commercially under Part 91 without certification—is illegal and carries serious safety and liability consequences.

Operational Control and Flight Following

Operational control means the legal authority to initiate, conduct, and terminate a flight. Under Part 135, this authority must rest with the certificated operator—not a broker or independent pilot.

Flight following systems using dispatchers or operations coordinators are required so the operator tracks each aircraft’s position and supports crews with weather, NOTAMs, and diversion decisions.

Confusion over operational control has contributed to several NTSB-investigated accidents and affects liability assignment in legal claims. Passengers can reasonably ask charter providers which company’s Part 135 certificate covers their flight.

Why Part 135 Matters for Passengers, Owners, and Accident Cases

Understanding Part 135 isn’t academic—it affects legal responsibilities, insurance coverage, accident investigations, and injured passengers’ rights.

When accidents occur on Part 135 flights, investigators examine whether the operator complied with pilot qualifications, duty times, maintenance, operational control, and weather decisions.

Violations—flying outside ops specs, unqualified pilots, ignored maintenance—can serve as evidence of negligence in civil lawsuits. Approximately 10% of 2022 Part 135 incidents involved exceeded duty times.

Aircraft owners allowing charter without proper certification face heightened liability if crashes occur during illegal commercial use.

RESQ specializes in handling aviation accident and injury cases, including Part 135 charter, air taxi, and air ambulance operations, with 26 years of experience helping victims and families understand applicable regulations and pursue appropriate compensation.

How Legal Teams Use Part 135 Rules in Investigations

Legal teams compare actual operations on accident days with the operator’s ops specs, crew schedules, maintenance logs, and weather briefings to identify deviations.

Findings like over-duty pilots, missed inspections, or unauthorized airports significantly strengthen claimants’ cases and influence settlements.

Because Part 135 requirements are complex, injured passengers benefit from counsel familiar with aviation regulations rather than general personal injury practitioners.

Families should preserve contracts, emails, itineraries, and booking confirmations showing the flight was sold as charter service, supporting Part 135 classification.

FAQs About What Is Part 135 in Aviation

Many readers have practical questions about how Part 135 affects them as travelers or aircraft owners. Here are answers to the most common inquiries.

How can I tell if my charter flight is operating under Part 135?

Ask for the operator’s legal name and Part 135 certificate number, then verify it against FAA databases. Reputable charter providers disclose the certificated operator in contracts. Reluctance to share this information is a red flag. Confirm the aircraft tail number appears under that certificate and that you’re not dealing with an illegal Part 91 operation misrepresented as commercial charter.

Can an aircraft owner legally charter out their jet without a Part 135 certificate?

Owners cannot lawfully offer flights to the public for compensation without operating under a valid Part 135 certificate—their own or via a management company holding one. Illegal charter exposes owners to regulatory penalties, insurance denial after accidents, and increased civil liability. Owners considering charter activity should consult experienced aviation counsel.

Are Part 135 charter flights safer than private Part 91 flights?

NTSB data shows lower accident rates for Part 135 operations (1.02 fatal accidents per 100,000 hours from 2009–2020) compared to Part 91 (5.5 per 100,000). This results from stricter training, maintenance, oversight, and fatigue management. However, safety varies by operator—strong safety culture matters as much as regulatory classification.

How does Part 135 affect what I pay for a charter flight?

Compliance costs—higher pilot salaries, recurrent training, structured maintenance, regulatory audits, insurance—are reflected in charter prices. Legitimate Part 135 operations cost 20–40% more than informal arrangements. Gray-market operators may quote lower prices by skipping requirements, but passengers face greater safety risks and legal uncertainty.

What should I do if I’m injured on a Part 135 flight?

Seek immediate medical care, then preserve documents: contracts, emails, itineraries, photos, and witness contacts. Report the incident to authorities and cooperate with NTSB/FAA investigations, but avoid signing settlements before obtaining legal advice. Specialized aviation attorneys can evaluate whether Part 135 regulations were followed and identify responsible parties.