A commercial air transport operator must have the following personnel EXCEPT?

In the context of a commercial air transport operator, each of the personnel roles listed plays a vital part in ensuring the safe and efficient operation of the airline. However, when considering the necessary roles in a broadly defined set of operational requirements, the Chief Mechanic role may not be universally mandated for all operators.

A Director of Operations oversees the overall flight operations, ensuring that all flights are conducted safely and in compliance with regulations. The Chief Pilot is responsible for the flight crew and the operational safety of flights, directly managing pilots and making key decisions about flight procedures. A Quality Manager is essential for maintaining the standards of safety and efficiency, overseeing compliance with regulations and ensuring quality assurance throughout the company's operations.

The Chief Mechanic, while crucial for maintenance and repair in many operations, is not a requisite position for all commercial air operators, especially if they contract maintenance out to certified third-party organizations. Consequently, it's possible for an air transport operator to fulfill its operational responsibilities without having a dedicated Chief Mechanic on the payroll. The operators may instead employ maintenance services as needed, depending on their operational model and regulatory framework they are adhering to.