Definition
A pilot designated to act as backup to the pilot in command of an aircraft during flight, qualified to operate the aircraft and assume control if the pilot in command becomes unable to do so. The second in command is required by regulation on certain aircraft types and operations, and must hold appropriate ratings for the aircraft being flown.
Plain English
The second pilot on board, qualified to fly the aircraft and ready to take over if the captain can't continue. Often called the co-pilot or first officer.
Context Anchor
Seen in crew assignments, flight logs, aircraft operating rules, and regulations for operations that require more than one pilot.
Derivation
Second comes from a word meaning “following” or “next.” Command comes from a word meaning “to entrust” or “to order.” Together, the phrase means the pilot who is next in the command structure after the pilot with final authority.
Why Pilots Care
Clarifies who holds legal command authority and who may log pilot-in-command time during a flight.
Intuition Check
Second In Command does not mean an informal helper or a less important passenger. In aviation, it is a formal crew position for a qualified pilot serving under the pilot in command.
Example Sentence 1
The captain briefed the second in command on the departure procedure before pushback.
Example Sentence 2
Regulations require a Second In Command when operating certain multi-engine aircraft for hire.