What certification must the second in command of an aircraft have under 14 CFR 121?

The correct certification for the second in command (SIC) of an aircraft under the regulations of 14 CFR 121 is the requirement for an Airline Transport Pilot certificate along with an SIC aircraft type rating. This reflects the regulatory standards that ensure safety and proficiency for pilots operating under Part 121, which governs the operation of scheduled air carriers.

An Airline Transport Pilot certificate demonstrates that a pilot has met the rigorous training, experience, and testing requirements set by the Federal Aviation Administration (FAA). These requirements are critical for ensuring that all pilots, particularly those in command and those serving as the second in command, possess the necessary skills to handle the complexities of commercial airline operations.

The additional requirement of an SIC aircraft type rating ensures that the pilot is specifically trained and tested for the particular aircraft type they are operating as a second in command. This specialized training is vital because different aircraft can have varying systems, performance characteristics, and operational procedures, making it essential for compliance and safety in multi-crew operations.

Having both the ATP certificate and the appropriate SIC type rating ensures that the pilot is equipped to handle their responsibilities efficiently and safely, contributing to the overall safety of the flight operation.