The regulatory definition of "flight time" under 14 CFR §1.1 is a foundational concept that student and early-career pilots frequently misunderstand, and the confusion has real consequences for certificate eligibility, airline hiring, and certificate action exposure. Per the FARs, flight time commences when an aircraft first moves under its own power for the purpose of flight and ends when it comes to rest at the next point of landing — a block-to-block standard, not a wheels-up/wheels-down (air time) standard. Air time, separately defined in §1.1, runs only from departure surface contact to arrival surface contact and is almost never the correct metric for logging toward aeronautical experience requirements. Hobbs meters, depending on configuration, may trigger on oil pressure at engine start or on a squat switch at liftoff, meaning Hobbs time can be shorter or longer than FAR flight time depending on the aircraft. The legally correct logbook entry is FAR flight time — first taxi movement to final stop — not raw air time, and not raw Hobbs, though in many training scenarios the three numbers cluster close together.
Airline hiring departments do conduct logbook audits, and the process has become increasingly rigorous as carriers use third-party verification services and cross-reference PRIA records, training records, and ATP-CTP completion documentation. Major carriers and regional airlines typically do not subpoena billing records from flight schools, but they do flag internal inconsistencies — entries that reflect suspiciously round numbers on every flight, total time that doesn't reconcile across categories, or instrument/night time that accumulates faster than the underlying cross-country or total time can support. A logbook in which every flight is logged to the nearest tenth with consistent, realistic variation (1.2, 1.7, etc.) does not raise flags; what draws scrutiny is a pattern of entries that appear fabricated, entries that cannot be corroborated by training records, or systematic inflation. Airlines increasingly use digital cross-checks and some require applicants to submit digital logbook exports in addition to paper records.
The question of CFI and student dual logging is governed by 14 CFR §61.51(e), which permits a flight instructor to log as PIC all time during which they are acting as a flight instructor. The student logs the same block of flight time as dual received. Both entries should reflect the same FAR flight time for the same flight — not two different numbers drawn from different timing sources. If a CFI and student are logging materially different durations for the same flight, one or both entries are incorrect. The resolution is simple: both parties log FAR block-to-block flight time from the same reference, and the numbers will match.
The broader issue flagged in the source discussion — student pilots at a flight school rounding up flight time by several minutes per flight — is logbook falsification regardless of scale. Intentional inflation of aeronautical experience entries constitutes a falsification under 14 CFR §61.59, which carries consequences ranging from certificate suspension to revocation and can trigger civil penalty action. The FAA does not routinely audit every student logbook in real time, but falsified entries surface during airline background checks, PRIA reviews, enforcement investigations, and accident inquiries. Pilots who inflate training-era logbooks carry that exposure indefinitely: the falsified records precede every certificate action, every medical application, and every airline application for the remainder of their careers. The professional aviation community, particularly at the regional and major carrier level, has grown less tolerant of logbook irregularities as hiring volumes have increased scrutiny pressure, and candidates discovered to have falsified entries are typically disqualified permanently from that carrier regardless of their subsequent total time.