Flying as a second-in-command (SIC) can be a valuable stepping stone in a pilot's career, but the rules governing when an SIC is required, what certificates and ratings that person must hold, and how SIC time may be logged are frequently tested on the FAA Commercial Pilot knowledge exam — and misunderstood in practice. A clear grasp of 14 CFR Parts 61 and 91 (and Part 135 where applicable) will help you both pass the test and operate legally.
At its core, the question of SIC requirements breaks into two parts: when does the regulation require an SIC, and when does a pilot act as SIC even if one is not strictly required? The answer to the first question depends on the aircraft type certificate and the operating rules under which the flight is conducted.
When Is an SIC Required?
Under 14 CFR §91.109 and §91.105, an SIC is not generally required for single-pilot operations in Part 91 general aviation flights unless the aircraft's type certificate or the Airplane Flight Manual (AFM) requires a second pilot. For turbine-powered, large, or commuter-category airplanes, the type certificate often mandates two-pilot crews. Additionally, any aircraft operated under an instrument flight rules (IFR) flight plan in certain categories may require an SIC per the aircraft's operating limitations. Under Part 135 (commuter and on-demand operations), the rules are stricter: many multi-engine turbine aircraft require an SIC regardless of the type certificate, and that SIC must meet the qualification standards spelled out in §135.245.
SIC Qualifications
14 CFR §61.55 does not itself set a minimum certificate level for the SIC seat — that requirement comes from the operating rule under which the flight is conducted (Part 91, 121, or 135), which typically calls for at least a private pilot certificate with the appropriate category and class rating for the aircraft. What §61.55 does establish is the second-in-command qualification requirements themselves: the required aeronautical knowledge, flight training, and a logbook endorsement showing the pilot has been found competent to serve as SIC in that type of aircraft. In addition, the SIC must hold an instrument rating if the flight is conducted under IFR. Under §61.55(b), the pilot must also have, within the preceding 24 calendar months, either satisfactorily completed a proficiency check in that aircraft type or, since the beginning of the 24th calendar month before the flight, served as PIC or SIC in that aircraft type — this is a 24-month recency requirement, not an annual one. Importantly, a type rating is not required for the SIC position (unlike the pilot-in-command), but the qualification and recency requirements of §61.55 must still be met.
Logging SIC Flight Time
Under 14 CFR §61.51(f), a pilot may log SIC time only when at least one of the following conditions is met:
- The pilot is required to be on the flight deck and qualified to serve as SIC under the applicable operating rule (e.g., the aircraft type certificate requires two pilots).
- The aircraft is being operated under Part 121 or Part 135 and the regulations require an SIC.
- The pilot acts as SIC of an aircraft that requires a type rating — even if a type rating is not held — because the regulations require more than one pilot.
A common point of confusion: a pilot sitting in the right seat of a complex single-engine airplane on a Part 91 flight cannot log that time as SIC unless the aircraft's type certificate or AFM actually requires two pilots. Simply occupying the right seat does not create a loggable SIC condition.
Why It Matters
Logging SIC time improperly can jeopardize certificate applications, airline hiring, and legal operation. Conversely, knowing when you can legally log SIC time helps you build flight experience efficiently. For aspiring airline pilots, SIC time logged under Part 121 or 135 may count toward ATP certificate requirements — making these rules directly tied to career progression.
Memory Aid
Think of it as "Required = Loggable." If the regulation or the aircraft's type certificate requires a second pilot, the person filling that seat can log the time. If neither requires it, SIC time generally cannot be logged under Part 91.
Common Test Traps
- Sitting ≠ Logging: Occupying the right seat in a single-pilot aircraft during a Part 91 flight does not automatically allow SIC time to be logged.
- Type rating not required for SIC: The SIC does not need a type rating for the aircraft — that requirement applies only to the PIC.
- Recency under §61.55 runs on a 24 calendar month cycle: SIC qualification is not a one-time event; the pilot must complete a proficiency check or have acted as PIC/SIC in the type within the preceding 24 calendar months.
- IFR flights add an instrument rating requirement: An SIC flying IFR must hold an instrument rating in addition to meeting the category and class requirements applicable under the operating rule.