The International Civil Aviation Organisation (ICAO) meticulously classifies civil aviation activities as:

• Commercial air transport services
  • Scheduled
  • Non-scheduled
    • Charter
    • On-demand (air-taxi, commercial business aviation, other)
    • Other
• General Aviation (GA)
  • Non-commercial business aviation
  • Instructional flying
  • Pleasure flying
  • Aerial work (agriculture, construction, surveying, photography, advertisement, SaR, etc.)
  • Other flying

Specifically, a commercial operation is any operation of an aircraft, in return for remuneration or other valuable consideration, which is available to the public or, when not made available to the public, which is performed under a contract between an operator and a customer, where the latter has no control over the operator.

In short, if an aircraft is used to provide a service for a charge, this is a commercial operation.

Commercial Air Transportation means an aircraft operation that transports passengers, cargo, or mail for remuneration or other valuable consideration. CAT is a type of commercial operation.

The other type of commercial operations is commercial specialized operations.

Specialized Operation (SPO) is any operation other than CAT where the aircraft is used for specialised activities such as:

• agriculture
• construction
• photography
• surveying
• observation and patrol
• aerial advertisement

NOTE:

• Commercial and Specialized operations are not exclusive, i.e., an SPO can be a commercial operation, but it also can be a non-commercial operation. For example, an agricultural work, if done by a farmer on their own farm, would be non-commercial. If the same farmer did the same activity on a neighbour's farm for a fee, this would be a commercial operation (but not a CAT since no transportation takes place).