What is the main difference between Part 91 and Part 135 operating rules?

Part 91 is the baseline general aviation rulebook that applies to all civil aircraft operations in the United States, while Part 135 is an additional, stricter set of rules that governs commuter and on-demand charter or air taxi operations conducted for compensation or hire. Part 135 raises weather minimums, imposes hard flight and duty time limits, and requires FAA-approved training programs and maintenance inspection programs that Part 91 does not mandate. Wherever Part 135 is silent, Part 91 still applies, so the two parts work together rather than replacing one another.

What are the VFR weather minimums under Part 135 compared to Part 91?

Under 14 CFR §135.205, Part 135 day VFR operations require at least a 1,000-foot ceiling and 3 statute miles of visibility, and night VFR requires at least a 1,500-foot ceiling and 5 statute miles of visibility. These are significantly more restrictive than basic Part 91 Class G airspace VFR minimums, which can be as low as 1 statute mile visibility and clear of clouds during the day at low altitudes. The higher Part 135 standards exist because charter operators are responsible for the safety of paying passengers.

Does a commercial pilot certificate allow you to conduct Part 135 charter flights?

No. A commercial pilot certificate gives an individual pilot the legal privilege to act as pilot in command for compensation or hire, but actually conducting charter or air taxi operations requires that the operating company hold a Part 135 Air Carrier Certificate issued by the FAA. The certificate is held by the operator, not the individual pilot, and the operator must have FAA-approved operations specifications, maintenance programs, and training programs before any for-hire passenger flights can be conducted under Part 135.

FAR Part 91 vs Part 135 Operating Rules Comparison

When you earn your commercial pilot certificate, you unlock the legal privilege to fly for compensation or hire—but that privilege immediately drops you into a regulatory landscape where how you operate matters as much as what you fly. Two frameworks dominate that landscape: 14 CFR Part 91, the foundational general aviation rulebook, and 14 CFR Part 135, which governs commuter and on-demand air carrier operations. Understanding both—where they overlap, where they diverge, and why the differences exist—is essential for every commercial pilot seeking real-world operational competence and for passing the FAA Commercial Pilot and Instrument Rating knowledge tests.

The Regulatory Foundation: What Each Part Does

Part 91 is the baseline. It applies to every civil aircraft operation in U.S. airspace unless a more specific part—such as Part 121, 135, or 137—explicitly overrides it. Think of Part 91 as the floor beneath every other operating rule. It sets minimums for airworthiness, pilot currency, fuel reserves, right-of-way, and VFR weather, among hundreds of other items.

Part 135 is a certificate-based overlay. To conduct charter or air taxi flights—carrying passengers or cargo for compensation or hire—the operator must hold a Part 135 Air Carrier Certificate issued by the FAA. Under Part 119, a small aircraft with a passenger-seat configuration of 30 seats or fewer and a maximum payload capacity of 7,500 pounds or less typically operates under the on-demand or commuter provisions of Part 135, but Part 135 also covers on-demand operations conducted in larger aircraft under other certificate structures, so the 30-seat/7,500-pound figures describe a common threshold rather than a universal cap on every Part 135 operation. The individual commercial pilot working for that operator flies under Part 135 rules whenever those rules are more restrictive than Part 91. Wherever Part 135 is silent, Part 91 still applies. These two parts are not mutually exclusive; they stack.

This distinction is foundational to a test trap many students fall into: earning a commercial pilot certificate does not authorize you to conduct Part 135 operations. The certificate must be held by the operator, not the pilot. A commercially certificated pilot can still operate legally for compensation under Part 91 in specific situations—flight instruction, banner towing, aerial photography, and certain ferry or ferry-type operations—without any Part 135 certificate being involved.

VFR Weather Minimums: The Most Tested Difference

Weather minimums are the single most commonly tested divergence between these two parts on FAA knowledge exams.

Under Part 91, VFR weather minimums vary by airspace class. In Class G airspace below 1,200 feet AGL during the day, a pilot needs only 1 statute mile visibility and must remain clear of clouds. These are deliberately permissive because Part 91 is designed for personal, non-revenue flight where the pilot bears the individual risk.

Part 135 applies a completely different standard. Under 14 CFR §135.205, no pilot may begin a VFR flight unless the ceiling is at least 1,000 feet and ground visibility is at least 3 statute miles during the day. For night VFR, the requirements jump to a ceiling of at least 1,500 feet and visibility of at least 5 statute miles. The reasoning is sound: a charter operator is responsible for paying passengers who cannot be expected to appreciate marginal meteorological conditions, and the cost of an accident in commercial operations extends far beyond the individual pilot.

For IFR approaches, Part 135 adds special minimums. Under §135.225, a Part 135 pilot may not begin an instrument approach unless current weather reports or forecasts—or a combination of both—indicate the destination airport's weather is at or above the applicable IFR minimums. Additionally, Part 135 operators are often required to add 100 feet and one-quarter mile to standard published minimums unless their operations specifications specifically authorize the lower published figures.

Flight Time Limits and Rest Requirements

Pilot fatigue is one of the most well-documented hazards in commercial aviation, which is why Part 135 imposes hard limits that simply do not exist for most Part 91 operations.

8 hours of flight time in any 24 consecutive hours is the basic limit for Part 135 single-pilot on-demand operations before a required rest period.
1,200 flight hours in any 12-calendar-month period is the annual ceiling.
120 flight hours in any 30-consecutive-day period.
34 flight hours in any 7-consecutive-day period, per §135.267 for unscheduled one- and two-pilot on-demand operations.
A minimum of 9 consecutive hours of rest must be provided before any flight time, and this rest period cannot be reduced below 8 hours with a compensating rest period following.

Part 91, by contrast, imposes no specific flight or duty time limitations on most general aviation operations (there are separate rules for Part 91 operators conducting air tour operations under §91.147, but the general recreational and business pilot has no hard FAA flight-time cap). This asymmetry reflects the underlying philosophy: Part 135 places the duty of safety on an operator accountable to the FAA through an operating certificate.

Aircraft Airworthiness and Maintenance Programs

Under Part 91, the pilot in command is ultimately responsible for determining that the aircraft is airworthy prior to flight per §91.7. The aircraft must comply with applicable Airworthiness Directives and be maintained under one of the inspection programs allowed by §91.409—typically an annual inspection for non-commercial operations.

Part 135 raises the bar significantly. The certificate holder bears an independent, ongoing obligation to maintain all aircraft in airworthy condition under an approved aircraft inspection program (AAIP) or a continuous airworthiness maintenance program. The maintenance requirements, record-keeping obligations, and inspection intervals are spelled out in the operator's operations specifications and must be approved by the FAA's Flight Standards District Office. The pilot-in-command's preflight responsibility does not disappear, but it is now layered on top of an operator-level maintenance infrastructure.

Minimum Equipment Lists

When equipment becomes inoperative, the rules diverge again. Part 91 operators without an approved MEL follow §91.213, which permits flight with certain inoperative instruments and equipment provided specific conditions are met—including that the inoperative item is not required by the VFR/IFR equipment regulations, not required by an AD, placarded as inoperative, and the aircraft is considered airworthy by a certificated mechanic or the pilot in command.

Part 135 operators must operate under an FAA-approved MEL when inoperative equipment is present. The MEL delineates exactly which items may be inoperative, under what conditions, and for how long—and the operator's operations specifications formally authorize its use. There is far less pilot discretion in the Part 135 environment.

Training, Checking, and Crew Requirements

Part 91 currency requirements—the flight review per §91.107, instrument currency per §61.57—fall on the individual pilot and are relatively flexible. Part 135 imposes a structured, operator-administered training program under §135.341 that must be approved by the FAA. Pilots must complete initial ground and flight training, pass an FAA-approved competency check conducted by a check airman, and attend recurrent training at specified intervals—typically every 12 calendar months. Instrument proficiency checks must also be completed at defined intervals. These requirements exist because Part 135 operations are public-interest transportation, not personal flight.

Key Numbers and Rules to Memorize

Part 135 day VFR minimums: 1,000-foot ceiling / 3 SM visibility
Part 135 night VFR minimums: 1,500-foot ceiling / 5 SM visibility
Part 135 basic flight time limit: 8 hours in 24 consecutive hours
Part 135 annual limit: 1,200 hours in 12 calendar months
Part 135 monthly limit: 120 hours in 30 consecutive days
Minimum rest before flight: 9 consecutive hours (reducible to 8 with compensating rest)
Part 135 certificate held by the operator, not the individual pilot

Common Test Traps

Part 91 is not replaced by Part 135—it underlies it. Part 135 adds rules; it does not erase Part 91's baseline requirements wherever Part 135 is silent.
Compensation alone does not trigger Part 135. Commercial pilots conducting banner towing, flight instruction, or aerial survey work operate legally under Part 91 even though they are paid.
The MEL distinction matters on the knowledge test. Part 91 operators without an approved MEL use the §91.213 process; Part 135 operators must have and use an FAA-approved MEL.
Do not confuse IFR approach minimums. Part 135 often requires adding 100 feet and one-quarter mile to published minimums unless the operator's ops specs say otherwise—this addition catches many students off guard.
Night VFR minimums are higher than day VFR under Part 135. Swapping 3 SM / 1,000 feet with 5 SM / 1,500 feet is a frequent distractor on weather minimum questions.