Part 121 vs Part 135…What’s the difference?

So, you’re starting flight training and keep hearing terms like Part 121 and Part 135 thrown around. What do they mean, and why should you care? These FAA regulations define how airlines and charter companies operate, and they’ll shape your career path depending on where you fly. Let’s break it down in plain English!

Part 121 vs. Part 135: The Basics

Think of Part 121 as the “big leagues” of scheduled airlines (like Delta or United), while Part 135 covers on-demand charters (like NetJets or air ambulances). Here’s some of how they differ:

Part 121

1. Scheduled flights (fixed routes/times)

2. Large jets (30+ seats)

3. Major airline pilots

Part 135

1. On-demand charters, cargo, tours

2. Smaller planes (9–30 seats)

3. Charter, corporate, or medevac pilots

Key Differences Explained

1. Operations & Aircraft

• Part 121 = Buses of the Sky

  • Think: Boeing 737s flying fixed routes (e.g., New York to Miami daily).

  • Strict schedules, high passenger volumes.

• Part 135 = Taxis of the Sky

  • Think: Cessna Citations flying private groups or urgent cargo.

  • No fixed schedule—you go where the client needs, when they need it.

2. Crew Rules

• Part 121:

  • Two pilots required for most flights.

  • Strict rest rules (e.g., 10 hours off between shifts).

• Part 135:

  • Single-pilot operations allowed for smaller planes.

  • More flexibility (but still regulated rest periods).

3. Certification & Oversight

• Part 121:

  • FAA approval takes years (rigorous safety checks, mandatory SMS programs).

  • Ideal for pilots who thrive in structured, high-compliance environments.

• Part 135:

  • Faster to certify (months vs. years).

  • Great for pilots who prefer variety and quicker career entry.

4. Maintenance

• Part 121:

  • Aircraft undergo frequent, detailed inspections (think: daily checks).

• Part 135:

  • Maintenance tailored to smaller fleets (less frequent but still strict).

Why This Matters for Your Career

1. Training Requirements

   • Part 121: Requires an Airline Transport Pilot (ATP) certificate (1,500 flight hours).

   • Part 135: Often hires pilots with a Commercial Pilot License (250+ hours).

2. Lifestyle Differences

   • Part 121: Predictable schedules (but long-haul trips, nights away).

   • Part 135: Flexible but irregular hours (ready for last-minute charters!).

3. Career Progression

   • Many pilots start in Part 135 to build hours before moving to Part 121 airlines.

Which Path is Right for You?

• Aim for Part 121 if:

  • You want to fly for major airlines.

  • You’re okay with a longer path (1,500 hours + ATP).

  • You prefer predictable schedules (eventually!).

• Consider Part 135 if:

  • You want to fly sooner (less hour requirements).

  • You enjoy variety (different destinations, cargo vs. passengers).

  • You’re okay with on-call or irregular hours.

Real-World Examples

• Part 121: Delta, American Airlines, UPS/FedEx cargo.

• Part 135: NetJets (private charters), Air Methods (air ambulances), regional tour companies.

Final Thoughts

Understanding Part 121 and Part 135 isn’t just about regulations—it’s about choosing the pilot lifestyle that fits you. Many aviators start in Part 135 to build experience before transitioning to airlines, but others love the flexibility of charter flying long-term. Whichever path you pick, knowing these differences will help you navigate your training and career goals with confidence.