PIC, Pilot In Command Log
https://www.aopa.org/training-and-safety/learn-to-fly/logging-cross-country-time/logbooks-and-logging-time#pilot
SIC, Second In Command Flight Time
Also: Lost Logs
Lost Log
The General Aviation Operation Inspectors Handbook provides guidance for reconstructing lost airman logbooks. The airman should begin with a signed and notarized statement of previous flight time as the basis for starting a new flight time record. Such a statement should be substantiated by all available evidence such as aircraft logbooks, receipts for aircraft rentals, and statements of flight operators. AOPA would also suggest statements from previous flight instructors, copies of medical applications, and Airman Certificate and/or Rating Applications (FAA Form 8710), which can all be obtained through the FAA.
Also important to remember is the need for documentation of a current flight review, takeoff and landing proficiency when carrying passengers, instrument proficiency if appropriate, and additional endorsements for high-performance, complex, tailwheel, and pressurized aircraft that have a service ceiling or maximum operating altitude, whichever is lower, above 25,000 feet msl, if applicable. If unable to locate the instructors who gave the initial endorsements, it may be necessary to obtain the appropriate endorsements again.
The FAA is also concerned with falsification of records. The Inspectors Handbook includes the warning, "A pilot who has lost logbooks or flight time records should be reminded that any fraudulent or intentional false statements concerning aeronautical experience are a basis for suspension or revocation of any certificate or rating held."
Many airmen periodically copy their logbooks and place the copies in secure locations. The logbook should be treated as a valuable personal document. You may want to reconsider carrying this document on every flight. Leaving it in your car, airplane, or in your flight bag with high-dollar headsets, which are targets for theft, is not recommended.