What a Part 135 operator is and how it is structured

01 What a Part 135 certificate actually authorises

Part 135 sits in the federal aviation regulations and covers commuter and on-demand operations. On-demand means the flight is arranged when the customer asks, rather than published on a schedule. Commuter operations sit in the same part with their own limits. The certificate names the kind of flying the holder may do and the aircraft it may do it with, so two operators holding the same part of the rules can be authorised for very different work.

The certificate is held by a business. That business may own its aircraft, lease them, or fly aircraft belonging to someone else under arrangements the rules describe. What the certificate does not do is qualify an individual pilot. A pilot needs a commercial certificate and the ratings for the aircraft, plus the experience the rules require for the kind of operation. The company holds the operating certificate; the pilot holds the pilot certificate. Both must line up before a revenue flight moves.

02 Who answers for safety inside the company

A Part 135 operator is built around named people who carry specific responsibilities. The rules require the company to put individuals in positions with defined duties, and the way those positions are staffed is part of what the certificate describes. The director of operations oversees flight operations and the pilots. The chief pilot supervises pilot qualifications and records. The director of maintenance oversees the maintenance programme and the people who carry it out. A chief inspector may sit over inspection and quality.

The point of naming people is accountability. When something goes wrong, the rules assume there is a person whose job it was to prevent it. A small operator may combine roles, and the certificate says how. The map of aviation work shows how many of these posts exist across the industry and who fills them.

03 How the aircraft stay legal to fly

Every aircraft on a Part 135 certificate lives inside a maintenance programme that the operator writes and the regulator accepts. That programme sets out what is inspected, how often, and by whom. Maintenance is performed under a repair station approval or by mechanics holding the right certificate, and the work is recorded so that the aircraft's condition can be traced forward from the last inspection.

The repair station approval is a separate document from the operating certificate, held by the shop rather than by the operator. A charter company that does its own maintenance holds both. A company that sends work out relies on the shop's approval. Either way the operator stays responsible for the airworthiness of aircraft it flies, which is why maintenance control sits close to the top of the organisation.

04 Where does the operating certificate stop and the pilot certificate start?

A pilot certificate and a Part 135 operating certificate are issued to different parties and checked at different moments. The pilot certificate follows the person from job to job. The operating certificate stays with the company and dies with it unless it is transferred under the rules.

The pilot certificates and ratings that a charter pilot needs are set by the kind of flying, not by the company name. A pilot who moves from one operator to another keeps the certificate but must be checked into the new company's procedures and aircraft before flying its customers.

05 Who oversees a charter operator once the certificate is issued

The Federal Aviation Administration issues the certificate and keeps watching afterwards. Aviation Safety, the branch of the agency responsible for certification, production approval and continued airworthiness, also certifies operational and maintenance enterprises in domestic civil aviation, runs civil flight operations and develops the regulations operators work under. Its oversight role covers roughly 7,300 U.S. commercial airlines and air operators, which is the population a Part 135 holder belongs to.

That oversight is not a single inspection. It is a continuing relationship: the operator reports changes, the regulator reviews them, and both sides track the aircraft, the pilots and the maintenance records. You can see how this branch is organised on the Aviation Safety page, which names the responsibilities in its own words and links to the forms the agency uses to hear from the operators it regulates.

06 How the rules reach the operator

Regulations are written, published for comment, and then issued. Once a rule binds Part 135 operators, each company has to fold it into its manuals, its training and its maintenance programme. The certificate does not change when a rule changes; what changes is what the holder must do to keep operating lawfully. The path a rule takes from proposal to the operators it binds is traced in how a federal aviation rule reaches the operators it binds.

07 What the operating certificate does not cover

A Part 135 certificate says nothing about how the company sells seats, prices a charter, or arranges fuel. Those are commercial matters outside the certificate. Nor does it cover the airport where the aircraft sits: who owns the field, whether it has a control tower and what fees apply are questions for the airport's owner and the local authority.

Ground handling on the ramp is usually another business. An FBO may fuel the aircraft, park it and take care of passengers on the ground, under its own arrangements and its own approvals. What an FBO does between two flights is a separate chain of work from the flight itself, even though both show up on the same invoice.

08 What a charter customer or a new employee can check

If you are booking a charter, the operating certificate is the document that says the company is allowed to fly you. If you are considering a job with one, the same certificate tells you which kind of flying the company is approved for and how its safety posts are staffed. Neither question is answered by the aircraft alone.

The agency keeps the record of which operators hold which authority, and the Aviation Safety branch is where the certification and oversight of those operators sits. If a detail about a specific company is not published, the operator's own certificate and the agency's records are where to look, not a summary page.

A charter flight asks several certificates to line up at once: the company's operating certificate, the pilot's certificate, the repair station's approval if maintenance goes out, and the approvals of everyone handling the aircraft on the ground. The Part 135 certificate is the one that ties the flight to a business, and the business to a regulator that keeps checking the paperwork long after the first passenger boards.

09 Where to continue

The pages below take what a Part 135 operator is and how it is structured a step further inside operations and upkeep, beginning with Fuel grades for piston and turbine aircraft and who supplies them, then move on to the next trade. Each one names the agency that holds the rule it describes.