Part 91 vs Part 135: Key Differences

Overview

Two of the most referenced Federal Aviation Regulations govern how aircraft are operated in the United States: 14 CFR Part 91 (general operating rules) and 14 CFR Part 135 (commuter and on-demand operations). Understanding the differences is critical for operators, pilots, and companies that use charter services.

Part 91: Private Operations

Part 91 governs general operating and flight rules for all civil aircraft within the United States. If you own or operate an aircraft for personal or business use (not for hire), you're operating under Part 91.

Key characteristics:

• No air carrier certificate required
• Pilot serves as final authority on airworthiness
• Maintenance can be performed by the owner/operator
• No mandatory drug and alcohol testing program
• Broader weather minimums for the pilot in command

Part 135: Charter & On-Demand Operations

Part 135 covers commuter and on-demand air carrier operations — essentially, flying people or cargo for compensation. This includes charter operations, air taxi services, and some air ambulance operations.

Key characteristics:

• Requires an Air Carrier Certificate (OpSpecs)
• Director of Operations and Chief Pilot required
• FAA-approved training programs
• Mandatory drug and alcohol testing
• Stricter maintenance programs (approved MEL)
• More restrictive weather minimums

Pilot Requirements Comparison

Requirement	Part 91	Part 135
PIC Certificate	PPL minimum	CPL minimum (ATP for some)
Medical	Varies by operation	Second-class minimum
Recurrent Training	BFR every 24 months	Annual checks + specific training
Instrument Currency	6 approaches in 6 months	Company-specific requirements
Drug Testing	Not required	Mandatory DOT program

Insurance Implications

Part 135 operations carry significantly higher insurance costs due to the increased liability of carrying passengers for hire. However, operators that maintain IS-BAO registration and comprehensive safety management systems often negotiate better rates.

How FlyCertify Helps Both

Whether you operate under Part 91 or Part 135, FlyCertify streamlines credential management:

• Part 91 operators: Track pilot currencies, medical expirations, and BFR dates
• Part 135 operators: Full compliance dashboard, crew qualification tracking, IS-BAO documentation support, and instant badge invalidation

See the employer dashboard →