PART 121, 125 and 135. Definitions and differences.

[Desert185]

Technically, yes.

[Happy Bird]

Part 1 – Definitions and Abbreviations
Part 13 – Investigation and Enforcement Procedures
Part 21 – Certification Procedures for Products and Parts
Part 23 – Airworthiness Standards: Normal, Utility, Acrobatic and Commuter Airplanes
Part 25 – Airworthiness Standards: Transport Category Airplanes
Part 27 – Airworthiness Standards: Normal Category Rotorcraft
Part 29 – Airworthiness Standards: Transport Category Rotorcraft
Part 33 – Airworthiness Standards: Aircraft Engines
Part 34 – Fuel Venting and Exhaust Emission Requirements for Turbine Engine Powered Airplanes
Part 35 – Airworthiness Standards: Propellers
Part 39 – Airworthiness Directives
Part 43 – Maintenance, Preventive Maintenance, Rebuilding, and Alteration
Part 45 – Identification and Registration Marking
Part 47 – Aircraft Registration
Part 61 – Certification: Pilots, Flight Instructors, and Ground Instructors
Part 65 – Certification: Airmen Other Than Flight Crewmembers
Part 67 – Medical Standards and Certification
Part 71 – Designation of Class A, Class B, Class C, Class D, and Class E Airspace Areas; Airways; Routes; and Reporting Points
Part 73 – Special Use Airspace
Part 91 – General Operating and Flight Rules
Part 97 – Standard Instrument Approach Procedures
Part 101 – Moored Balloons, Kites, Unmanned Rockets and Unmanned Free Balloons
Part 103 – Ultralight Vehicles
Part 105 – Parachute Operations
Part 119 – Certification: Air Carriers and Commercial Operators
Part 121 – Operating Requirements: Domestic, Flag, and Supplemental Operations
Part 125 – Certification and Operations: Airplanes Having a Seating Capacity of 20 or More Passengers or a Payload Capacity of 6,000 Pounds or More
Part 129 – is a foreign carrier or operator of U.S. Aircraft
Part 133 – Rotorcraft External-Load Operations
Part 135 – Operating Requirements: Commuter and On Demand Operations and Rules Governing Persons on Board Such Aircraft
Part 136 – Commercial Air Tours and National Parks Air Tour Management
Part 137 – Agricultural Aircraft Operations
Part 139 – Certification of Airports
Part 141 – Flight Schools
Part 142 – Training Centers
Part 145 – Repair Stations
Part 147 – Aviation Maintenance Technicians Schools
Part 183 – Representatives of The Administrator
Regulations of interestEdit

The FARs are divided into tens of thousands of separate sections, many of which have large numbers of researchers using them on any given day. A few of the regulations particularly interesting to laypersons, relevant to current political issues, or of historical interest are listed below.

http://en.m.wikipedia.org/wiki/Feder...on_Regulations

[Swear_in_GIN]

So a Beech 1900 with 19 seats (duh) operating as a scheduled airliner would be Part 121 or 125? Talk about headspin.

[zondaracer]

It's not about the size or weight of the aircraft....it's the number of available passenger seats. A large long haul jet can be operated under part 135 and flown for hire around the world as long as the passenger seating configuration is under (I believe the numbe is) 20.

The number is 30 seats, and the limit is based on the type certificate. A 777 is type certificated above 30 seats, so you could not operate a 777 under part 135. A BBJ is type certificated at 30 seats or less, so you could operate it under part 135.

[zondaracer]

A Beech 1900 could be operated under part 135 for non-scheduled operations. Scheduled operations would be part 121. Great Lakes got a supplemental type certificate for 9 seats, so they can operate the 9 seat version as part 135 on scheduled operations.

0-9 seats - part 135 scheduled or non scheduled
10-30 seats - part 135 non scheduled only

[340drvr]

Originally Posted by zondaracer

A Beech 1900 could be operated under part 135 for non-scheduled operations. Scheduled operations would be part 121. Great Lakes got a supplemental type certificate for 9 seats, so they can operate the 9 seat version as part 135 on scheduled operations.

0-9 seats - part 135 scheduled or non scheduled
10-30 seats - part 135 non scheduled only

Yup, that's the way Great Lakes changed configuration so they could avoid the new 121 rules for FO's requiring an ATP certificate. Under 135, they can still use right-seaters with way less time and only a commercial pilot certificate.
Just to confuse things even more, I may be wrong, but I believe there are several freight operators using 1900's, single pilot, under 135 for freight-only. The Metroliner and EMB 110 work for this, too, 135 freight ops.

[MarkerInbound]

So a Beech 1900 with 19 seats (duh) operating as a scheduled airliner would be Part 121 or 125? Talk about headspin.

There is a concept of "holding out" in the FAA guidance which you can think of as advertising. If a company says, "We have a flight at noon from ABC to XYZ and tickets are $100" they are holding out to the public to provide common carriage between ABC and XYZ. That would fall under 121. A company may have facilities at many locations and have their own air operations to shuttle employees between those locations. General Motors used to do this out of Detroit with CV-580s. But these flights were not open to the general public. They fell under 125.

So in your example "operating as a scheduled airline" means it would fall under 121. You won't hear about much 125 stuff unless you are part of that operation since by definition they can't advertise.

[Spooky 2]

Generally speaking you cannot hold out for charter with a Part 125 cert. A typical exception would be if you were running a lets say a baseball team that owned and operated their own 757, they could with specific FAA approvals, charter that same airplane to another baseball, football or basketball team. There are limits on how this is structured regarding compensation etc.

Another example would the 757 that Trump owns. It is a classic example of a Part 125 operation.