What medical certification is required for a second in command under 14 CFR 121?

The requirement for a second in command (SIC) under 14 CFR 121 is indeed a second-class medical certification. This is essential because the Federal Aviation Administration (FAA) mandates that all pilots, including those serving as second in command, must hold a valid medical certificate that ensures they meet the necessary health standards to operate an aircraft safely.

A second-class medical certificate is specifically designed for pilots operating under part 121, which covers scheduled air carriers. This level of certification requires that the pilot demonstrates adequate vision, hearing, and general health, thus ensuring that they can perform their duties effectively and safely in the cockpit. It encompasses various medical standards tailored to the responsibilities of commercial aviation, focusing on the ability to operate an aircraft without jeopardizing the safety of the flight or its passengers.

While other classes of medical certificates exist, they cater to different flying privileges. A first-class medical certificate is typically more stringent and is required for pilots acting as pilot-in-command of airline operations, while a third-class medical is sufficient for certain private pilot operations but does not meet the requirements for second in command under part 121 operations. Therefore, the second-class medical certification is the appropriate and required standard for this role in commercial aviation operations.